finish implementing #6935

23 files changed, 395 insertions, 546 deletions

diff --git a/src/backend/taler-merchant-httpd_get-tips-ID.c b/src/backend/taler-merchant-httpd_get-tips-ID.c
index 09640bde..5b0abd89 100644
--- a/src/backend/taler-merchant-httpd_get-tips-ID.c
+++ b/src/backend/taler-merchant-httpd_get-tips-ID.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  (C) 2014-2020 Taler Systems SA
+  (C) 2014-2021 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify it under the
   terms of the GNU Affero General Public License as published by the Free Software
@@ -244,15 +244,14 @@ TMH_get_tips_ID (const struct TMH_RequestHandler *rh,
       else
       {
         json_t *context;
-        context = json_pack ("{s:s, s:s, s:s}",
-                             "remaining_tip",
-                             TALER_amount2s (&remaining),
-                             "taler_tip_uri",
-                             uri,
-                             "taler_tip_qrcode_svg",
-                             qr);
-        GNUNET_assert (NULL != context);
 
+        context = GNUNET_JSON_PACK (
+          TALER_JSON_pack_amount ("remaining_tip",
+                                  &remaining),
+          GNUNET_JSON_pack_string ("taler_tip_uri",
+                                   uri),
+          GNUNET_JSON_pack_string ("taler_tip_qrcode_svg",
+                                   qr));
         ret = TMH_return_from_template (connection,
                                         ( (0 == remaining.value) &&
                                           (0 == remaining.fraction) )
@@ -273,19 +272,18 @@ TMH_get_tips_ID (const struct TMH_RequestHandler *rh,
     }
     else
     {
-      ret = TALER_MHD_reply_json_pack (connection,
-                                       ( (0 == remaining.value) &&
-                                         (0 == remaining.fraction) )
-                                       ? MHD_HTTP_GONE
-                                       : MHD_HTTP_OK,
-                                       "{s:s, s:o, s:o}",
-                                       "exchange_url",
-                                       exchange_url,
-                                       "tip_amount",
-                                       TALER_JSON_from_amount (&remaining),
-                                       "expiration",
-                                       GNUNET_JSON_from_time_abs (
-                                         expiration_round));
+      ret = TALER_MHD_REPLY_JSON_PACK (
+        connection,
+        ( (0 == remaining.value) &&
+          (0 == remaining.fraction) )
+        ? MHD_HTTP_GONE
+        : MHD_HTTP_OK,
+        GNUNET_JSON_pack_string ("exchange_url",
+                                 exchange_url),
+        TALER_JSON_pack_amount ("tip_amount",
+                                &remaining),
+        GNUNET_JSON_pack_time_abs ("expiration",
+                                   expiration_round));
     }
     GNUNET_free (exchange_url);
     return ret;
diff --git a/src/backend/taler-merchant-httpd_post-orders-ID-abort.c b/src/backend/taler-merchant-httpd_post-orders-ID-abort.c
index 759c3ba5..f0b2a0c2 100644
--- a/src/backend/taler-merchant-httpd_post-orders-ID-abort.c
+++ b/src/backend/taler-merchant-httpd_post-orders-ID-abort.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  (C) 2014-2020 Taler Systems SA
+  (C) 2014-2021 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify
   it under the terms of the GNU Affero General Public License as
@@ -27,6 +27,7 @@
 #include <taler/taler_json_lib.h>
 #include <taler/taler_exchange_service.h>
 #include "taler-merchant-httpd_exchanges.h"
+#include "taler-merchant-httpd_helper.h"
 
 
 /**
@@ -366,49 +367,44 @@ generate_success_response (struct AbortContext *ac)
          (0 == rdi->http_status) ||
          (NULL == rdi->exchange_reply) )
       hc = MHD_HTTP_BAD_GATEWAY;
-    detail = (MHD_HTTP_OK != rdi->http_status)
-             ? json_pack ("{s:s, s:I, s:I, s:O?}",
-                          "type",
-                          "failure",
-                          "exchange_status",
-                          (json_int_t) rdi->http_status,
-                          "exchange_code",
-                          (json_int_t)
-                          (NULL != rdi->exchange_reply)
-                          ? TALER_JSON_get_error_code (
-                            rdi->exchange_reply)
-                          : TALER_EC_GENERIC_INVALID_RESPONSE,
-                          "exchange_reply",
-                          rdi->exchange_reply)
-             : json_pack ("{s:s, s:I, s:o, s:o}",
-                          "type",
-                          "success",
-                          "exchange_status",
-                          (json_int_t) rdi->http_status,
-                          "exchange_sig",
-                          GNUNET_JSON_from_data_auto (&rdi->exchange_sig),
-                          "exchange_pub",
-                          GNUNET_JSON_from_data_auto (&rdi->exchange_pub));
-    if ( (NULL == detail) ||
-         (0 != json_array_append_new (refunds,
-                                      detail)) )
-    {
-      json_decref (refunds);
-      GNUNET_break (0);
-      resume_abort_with_error (ac,
-                               MHD_HTTP_INTERNAL_SERVER_ERROR,
-                               TALER_EC_GENERIC_JSON_ALLOCATION_FAILURE,
-                               "could not create JSON array");
-      return;
-    }
+    if (MHD_HTTP_OK != rdi->http_status)
+      detail = GNUNET_JSON_PACK (
+        GNUNET_JSON_pack_string ("type",
+                                 "failure"),
+        GNUNET_JSON_pack_uint64 ("exchange_status",
+                                 rdi->http_status),
+        GNUNET_JSON_pack_uint64 ("exchange_code",
+                                 (NULL != rdi->exchange_reply)
+                                                          ?
+                                 TALER_JSON_get_error_code (
+                                   rdi->exchange_reply)
+                                                          :
+                                 TALER_EC_GENERIC_INVALID_RESPONSE),
+        GNUNET_JSON_pack_allow_null (
+          GNUNET_JSON_pack_object_incref ("exchange_reply",
+                                          rdi->exchange_reply)));
+    else
+      detail = GNUNET_JSON_PACK (
+        GNUNET_JSON_pack_string ("type",
+                                 "success"),
+        GNUNET_JSON_pack_uint64 ("exchange_status",
+                                 rdi->http_status),
+        GNUNET_JSON_pack_data_auto ("exchange_sig",
+                                    &rdi->exchange_sig),
+        GNUNET_JSON_pack_data_auto ("exchange_pub",
+                                    &rdi->exchange_pub));
+    GNUNET_assert (0 ==
+                   json_array_append_new (refunds,
+                                          detail));
   }
 
   /* Resume and send back the response.  */
-  resume_abort_with_response (ac,
-                              hc,
-                              TALER_MHD_make_json_pack ("{s:o}",
-                                                        "refunds",
-                                                        refunds));
+  resume_abort_with_response (
+    ac,
+    hc,
+    TALER_MHD_MAKE_JSON_PACK (
+      GNUNET_JSON_pack_array_steal ("refunds",
+                                    refunds)));
 }
 
 
@@ -534,13 +530,9 @@ process_abort_with_exchange (void *cls,
     resume_abort_with_response (
       ac,
       MHD_HTTP_GATEWAY_TIMEOUT,
-      TALER_MHD_make_json_pack (
-        "{s:s, s:I}",
-        "hint",
-        TALER_ErrorCode_get_hint (
-          TALER_EC_MERCHANT_GENERIC_EXCHANGE_TIMEOUT),
-        "code",
-        (json_int_t) TALER_EC_MERCHANT_GENERIC_EXCHANGE_TIMEOUT));
+      TALER_MHD_make_error (
+        TALER_EC_MERCHANT_GENERIC_EXCHANGE_TIMEOUT,
+        NULL));
     return;
   }
   if (NULL == exchange_handle)
@@ -550,14 +542,10 @@ process_abort_with_exchange (void *cls,
     resume_abort_with_response (
       ac,
       MHD_HTTP_BAD_GATEWAY,
-      TALER_MHD_make_json_pack (
-        "{s:s, s:I, s:I, s:I, s:O?}",
-        "hint", TALER_ErrorCode_get_hint (
+      TALER_MHD_MAKE_JSON_PACK (
+        TALER_JSON_pack_ec (
           TALER_EC_MERCHANT_GENERIC_EXCHANGE_CONNECT_FAILURE),
-        "code", (json_int_t) TALER_EC_MERCHANT_GENERIC_EXCHANGE_CONNECT_FAILURE,
-        "exchange_http_status", (json_int_t) hr->http_status,
-        "exchange_code", (json_int_t) hr->ec,
-        "exchange_reply", hr->reply));
+        TMH_pack_exchange_reply (hr)));
     return;
   }
   /* Initiate refund operation for all coins of
diff --git a/src/backend/taler-merchant-httpd_post-orders-ID-claim.c b/src/backend/taler-merchant-httpd_post-orders-ID-claim.c
index 8b3b80ea..537ea0e1 100644
--- a/src/backend/taler-merchant-httpd_post-orders-ID-claim.c
+++ b/src/backend/taler-merchant-httpd_post-orders-ID-claim.c
@@ -267,12 +267,13 @@ TMH_post_orders_ID_claim (const struct TMH_RequestHandler *rh,
     GNUNET_CRYPTO_eddsa_sign (&hc->instance->merchant_priv.eddsa_priv,
                               &pdps,
                               &merchant_sig);
-    return TALER_MHD_reply_json_pack (
+    return TALER_MHD_REPLY_JSON_PACK (
       connection,
       MHD_HTTP_OK,
-      "{ s:o, s:o }",
-      "contract_terms", contract_terms,
-      "sig", GNUNET_JSON_from_data_auto (&merchant_sig));
+      GNUNET_JSON_pack_object_steal ("contract_terms",
+                                     contract_terms),
+      GNUNET_JSON_pack_data_auto ("sig",
+                                  &merchant_sig));
   }
 }
 
diff --git a/src/backend/taler-merchant-httpd_post-orders-ID-refund.c b/src/backend/taler-merchant-httpd_post-orders-ID-refund.c
index 22c9f717..27622d63 100644
--- a/src/backend/taler-merchant-httpd_post-orders-ID-refund.c
+++ b/src/backend/taler-merchant-httpd_post-orders-ID-refund.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  (C) 2020 Taler Systems SA
+  (C) 2020-2021 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify
   it under the terms of the GNU Affero General Public License as
@@ -738,60 +738,60 @@ TMH_post_orders_ID_refund (const struct TMH_RequestHandler *rh,
       {
         if (NULL == cr->exchange_reply)
         {
-          refund = json_pack ("{s:s,s:I,s:I,s:o,s:o,s:o}",
-                              "type",
-                              "failure",
-                              "exchange_status",
-                              (json_int_t) cr->exchange_status,
-                              "rtransaction_id",
-                              (json_int_t) cr->rtransaction_id,
-                              "coin_pub",
-                              GNUNET_JSON_from_data_auto (&cr->coin_pub),
-                              "refund_amount",
-                              TALER_JSON_from_amount (&cr->refund_amount),
-                              "execution_time",
-                              GNUNET_JSON_from_time_abs (cr->execution_time));
+          refund = GNUNET_JSON_PACK (
+            GNUNET_JSON_pack_string ("type",
+                                     "failure"),
+            GNUNET_JSON_pack_uint64 ("exchange_status",
+                                     cr->exchange_status),
+            GNUNET_JSON_pack_uint64 ("rtransaction_id",
+                                     cr->rtransaction_id),
+            GNUNET_JSON_pack_data_auto ("coin_pub",
+                                        &cr->coin_pub),
+            TALER_JSON_pack_amount ("refund_amount",
+                                    &cr->refund_amount),
+            GNUNET_JSON_pack_time_abs ("execution_time",
+                                       cr->execution_time));
         }
         else
         {
-          refund = json_pack ("{s:s,s:I,s:I,s:O,s:I,s:o,s:o,s:o}",
-                              "type",
-                              "failure",
-                              "exchange_status",
-                              (json_int_t) cr->exchange_status,
-                              "exchange_code",
-                              (json_int_t) cr->exchange_code,
-                              "exchange_reply",
-                              cr->exchange_reply,
-                              "rtransaction_id",
-                              (json_int_t) cr->rtransaction_id,
-                              "coin_pub",
-                              GNUNET_JSON_from_data_auto (&cr->coin_pub),
-                              "refund_amount",
-                              TALER_JSON_from_amount (&cr->refund_amount),
-                              "execution_time",
-                              GNUNET_JSON_from_time_abs (cr->execution_time));
+          refund = GNUNET_JSON_PACK (
+            GNUNET_JSON_pack_string ("type",
+                                     "failure"),
+            GNUNET_JSON_pack_uint64 ("exchange_status",
+                                     cr->exchange_status),
+            GNUNET_JSON_pack_uint64 ("exchange_code",
+                                     cr->exchange_code),
+            GNUNET_JSON_pack_object_incref ("exchange_reply",
+                                            cr->exchange_reply),
+            GNUNET_JSON_pack_uint64 ("rtransaction_id",
+                                     cr->rtransaction_id),
+            GNUNET_JSON_pack_data_auto ("coin_pub",
+                                        &cr->coin_pub),
+            TALER_JSON_pack_amount ("refund_amount",
+                                    &cr->refund_amount),
+            GNUNET_JSON_pack_time_abs ("execution_time",
+                                       cr->execution_time));
         }
       }
       else
       {
-        refund = json_pack ("{s:s,s:I,s:o,s:o,s:I,s:o,s:o,s:o}",
-                            "type",
-                            "success",
-                            "exchange_status",
-                            (json_int_t) cr->exchange_status,
-                            "exchange_sig",
-                            GNUNET_JSON_from_data_auto (&cr->exchange_sig),
-                            "exchange_pub",
-                            GNUNET_JSON_from_data_auto (&cr->exchange_pub),
-                            "rtransaction_id",
-                            (json_int_t) cr->rtransaction_id,
-                            "coin_pub",
-                            GNUNET_JSON_from_data_auto (&cr->coin_pub),
-                            "refund_amount",
-                            TALER_JSON_from_amount (&cr->refund_amount),
-                            "execution_time",
-                            GNUNET_JSON_from_time_abs (cr->execution_time));
+        refund = GNUNET_JSON_PACK (
+          GNUNET_JSON_pack_string ("type",
+                                   "success"),
+          GNUNET_JSON_pack_uint64 ("exchange_status",
+                                   cr->exchange_status),
+          GNUNET_JSON_pack_data_auto ("exchange_sig",
+                                      &cr->exchange_sig),
+          GNUNET_JSON_pack_data_auto ("exchange_pub",
+                                      &cr->exchange_pub),
+          GNUNET_JSON_pack_uint64 ("rtransaction_id",
+                                   cr->rtransaction_id),
+          GNUNET_JSON_pack_data_auto ("coin_pub",
+                                      &cr->coin_pub),
+          TALER_JSON_pack_amount ("refund_amount",
+                                  &cr->refund_amount),
+          GNUNET_JSON_pack_time_abs ("execution_time",
+                                     cr->execution_time));
       }
       GNUNET_assert (
         0 ==
@@ -799,16 +799,15 @@ TMH_post_orders_ID_refund (const struct TMH_RequestHandler *rh,
                                refund));
     }
 
-    return TALER_MHD_reply_json_pack (
+    return TALER_MHD_REPLY_JSON_PACK (
       connection,
       MHD_HTTP_OK,
-      "{s:o, s:o, s:o}",
-      "refund_amount",
-      TALER_JSON_from_amount (&prd->refund_amount),
-      "refunds",
-      ra,
-      "merchant_pub",
-      GNUNET_JSON_from_data_auto (&hc->instance->merchant_pub));
+      TALER_JSON_pack_amount ("refund_amount",
+                              &prd->refund_amount),
+      GNUNET_JSON_pack_array_steal ("refunds",
+                                    ra),
+      GNUNET_JSON_pack_data_auto ("merchant_pub",
+                                  &hc->instance->merchant_pub));
   }
 
   return MHD_YES;
diff --git a/src/backend/taler-merchant-httpd_post-tips-ID-pickup.c b/src/backend/taler-merchant-httpd_post-tips-ID-pickup.c
index 2bdef2bc..bd327b56 100644
--- a/src/backend/taler-merchant-httpd_post-tips-ID-pickup.c
+++ b/src/backend/taler-merchant-httpd_post-tips-ID-pickup.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  (C) 2017-2020 Taler Systems SA
+  (C) 2017-2021 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify it under the
   terms of the GNU General Public License as published by the Free Software
@@ -25,6 +25,7 @@
 #include <taler/taler_signatures.h>
 #include "taler-merchant-httpd.h"
 #include "taler-merchant-httpd_mhd.h"
+#include "taler-merchant-httpd_helper.h"
 #include "taler-merchant-httpd_exchanges.h"
 #include "taler-merchant-httpd_post-tips-ID-pickup.h"
 
@@ -292,12 +293,9 @@ withdraw_cb (void *cls,
     stop_operations (pc);
     pc->http_status = MHD_HTTP_BAD_GATEWAY;
     pc->response =
-      TALER_MHD_make_json_pack (
-        "{s:I, s:I, s:I, s:O}",
-        "code", (json_int_t) TALER_EC_MERCHANT_TIP_PICKUP_EXCHANGE_ERROR,
-        "exchange_code", (json_int_t) hr->ec,
-        "exchange_http_status", (json_int_t) hr->http_status,
-        "exchange_reply", hr->reply);
+      TALER_MHD_MAKE_JSON_PACK (
+        TALER_JSON_pack_ec (TALER_EC_MERCHANT_TIP_PICKUP_EXCHANGE_ERROR),
+        TMH_pack_exchange_reply (hr));
     MHD_resume_connection (pc->connection);
     TMH_trigger_daemon ();   /* we resumed, kick MHD */
     return;
@@ -359,13 +357,9 @@ do_withdraw (void *cls,
                                  po);
     GNUNET_free (po);
     pc->http_status = MHD_HTTP_GATEWAY_TIMEOUT;
-    pc->response = TALER_MHD_make_json_pack (
-      "{s:s, s:I}",
-      "hint",
-      TALER_ErrorCode_get_hint (
-        TALER_EC_MERCHANT_GENERIC_EXCHANGE_TIMEOUT),
-      "code",
-      (json_int_t) TALER_EC_MERCHANT_GENERIC_EXCHANGE_TIMEOUT);
+    pc->response = TALER_MHD_MAKE_JSON_PACK (
+      TALER_JSON_pack_ec (
+        TALER_EC_MERCHANT_GENERIC_EXCHANGE_TIMEOUT));
     MHD_resume_connection (pc->connection);
     TMH_trigger_daemon ();   /* we resumed, kick MHD */
     return;
@@ -379,14 +373,10 @@ do_withdraw (void *cls,
     GNUNET_free (po);
     pc->http_status = MHD_HTTP_BAD_GATEWAY;
     pc->response =
-      TALER_MHD_make_json_pack (
-        "{s:s, s:I, s:I, s:I, s:O?}",
-        "hint", TALER_ErrorCode_get_hint (
+      TALER_MHD_MAKE_JSON_PACK (
+        TALER_JSON_pack_ec (
           TALER_EC_MERCHANT_GENERIC_EXCHANGE_CONNECT_FAILURE),
-        "code", (json_int_t) TALER_EC_MERCHANT_GENERIC_EXCHANGE_CONNECT_FAILURE,
-        "exchange_code", (json_int_t) hr->ec,
-        "exchange_http_status", (json_int_t) hr->http_status,
-        "exchange_reply", hr->reply);
+        TMH_pack_exchange_reply (hr));
     MHD_resume_connection (pc->connection);
     TMH_trigger_daemon ();   /* we resumed, kick MHD */
     return;
@@ -485,10 +475,8 @@ compute_total_requested (void *cls,
   if (NULL == hr)
   {
     pc->http_status = MHD_HTTP_GATEWAY_TIMEOUT;
-    pc->response = TALER_MHD_make_json_pack (
-      "{s:I, s:s}",
-      "code", (json_int_t) TALER_EC_MERCHANT_GENERIC_EXCHANGE_TIMEOUT,
-      "hint", TALER_ErrorCode_get_hint (
+    pc->response = TALER_MHD_MAKE_JSON_PACK (
+      TALER_JSON_pack_ec (
         TALER_EC_MERCHANT_GENERIC_EXCHANGE_TIMEOUT));
     MHD_resume_connection (pc->connection);
     TMH_trigger_daemon ();   /* we resumed, kick MHD */
@@ -498,14 +486,10 @@ compute_total_requested (void *cls,
   {
     pc->http_status = MHD_HTTP_BAD_GATEWAY;
     pc->response =
-      TALER_MHD_make_json_pack (
-        "{s:I, s:s, s:I, s:I, s:O}",
-        "code", (json_int_t) TALER_EC_MERCHANT_GENERIC_EXCHANGE_CONNECT_FAILURE,
-        "hint", TALER_ErrorCode_get_hint (
+      TALER_MHD_MAKE_JSON_PACK (
+        TALER_JSON_pack_ec (
           TALER_EC_MERCHANT_GENERIC_EXCHANGE_CONNECT_FAILURE),
-        "exchange_code", (json_int_t) hr->ec,
-        "exchange_http_status", (json_int_t) hr->http_status,
-        "exchange_reply", hr->reply);
+        TMH_pack_exchange_reply (hr));
     MHD_resume_connection (pc->connection);
     TMH_trigger_daemon ();   /* we resumed, kick MHD */
     return;
@@ -514,14 +498,10 @@ compute_total_requested (void *cls,
   {
     pc->http_status = MHD_HTTP_BAD_GATEWAY;
     pc->response =
-      TALER_MHD_make_json_pack (
-        "{s:I, s:s, s:I, s:I, s:O}",
-        "code", (json_int_t) TALER_EC_MERCHANT_GENERIC_EXCHANGE_KEYS_FAILURE,
-        "hint", TALER_ErrorCode_get_hint (
+      TALER_MHD_MAKE_JSON_PACK (
+        TALER_JSON_pack_ec (
           TALER_EC_MERCHANT_GENERIC_EXCHANGE_KEYS_FAILURE),
-        "exchange_code", (json_int_t) hr->ec,
-        "exchange_http_status", (json_int_t) hr->http_status,
-        "exchange_reply", hr->reply);
+        TMH_pack_exchange_reply (hr));
     MHD_resume_connection (pc->connection);
     TMH_trigger_daemon ();   /* we resumed, kick MHD */
     return;
@@ -540,13 +520,10 @@ compute_total_requested (void *cls,
     {
       pc->http_status = MHD_HTTP_CONFLICT;
       pc->response =
-        TALER_MHD_make_json_pack (
-          "{s:I, s:I, s:I, s:O}",
-          "code",
-          (json_int_t) TALER_EC_MERCHANT_TIP_PICKUP_DENOMINATION_UNKNOWN,
-          "exchange_code", (json_int_t) hr->ec,
-          "exchange_http_status", (json_int_t) hr->http_status,
-          "exchange_reply", hr->reply);
+        TALER_MHD_MAKE_JSON_PACK (
+          TALER_JSON_pack_ec (
+            TALER_EC_MERCHANT_TIP_PICKUP_DENOMINATION_UNKNOWN),
+          TMH_pack_exchange_reply (hr));
       MHD_resume_connection (pc->connection);
       TMH_trigger_daemon ();   /* we resumed, kick MHD */
       return;
@@ -869,17 +846,16 @@ RETRY:
             GNUNET_assert (0 ==
                            json_array_append_new (
                              blind_sigs,
-                             json_pack ("{s:o}",
-                                        "blind_sig",
-                                        GNUNET_JSON_from_rsa_signature (
-                                          sigs[i]))));
+                             GNUNET_JSON_PACK (
+                               GNUNET_JSON_pack_rsa_signature ("blind_sig",
+                                                               sigs[i]))));
             GNUNET_CRYPTO_rsa_signature_free (sigs[i]);
           }
-          return TALER_MHD_reply_json_pack (
+          return TALER_MHD_REPLY_JSON_PACK (
             connection,
             MHD_HTTP_OK,
-            "{s:o}",
-            "blind_sigs", blind_sigs);
+            GNUNET_JSON_pack_array_steal ("blind_sigs",
+                                          blind_sigs));
         }
         break;
       case GNUNET_DB_STATUS_SOFT_ERROR:
diff --git a/src/lib/merchant_api_lock_product.c b/src/lib/merchant_api_lock_product.c
index e9593fdb..a3c345d5 100644
--- a/src/lib/merchant_api_lock_product.c
+++ b/src/lib/merchant_api_lock_product.c
@@ -168,18 +168,13 @@ TALER_MERCHANT_product_lock (
   struct TALER_MERCHANT_ProductLockHandle *plh;
   json_t *req_obj;
 
-  req_obj = json_pack ("{s:o, s:o, s:I}",
-                       "lock_uuid",
-                       GNUNET_JSON_from_data_auto (uuid),
-                       "duration",
-                       GNUNET_JSON_from_time_rel (duration),
-                       "quantity",
-                       (json_int_t) quantity);
-  if (NULL == req_obj)
-  {
-    GNUNET_break (0);
-    return NULL;
-  }
+  req_obj = GNUNET_JSON_PACK (
+    GNUNET_JSON_pack_data_auto ("lock_uuid",
+                                uuid),
+    GNUNET_JSON_pack_time_rel ("duration",
+                               duration),
+    GNUNET_JSON_pack_uint64 ("quantity",
+                             quantity));
   plh = GNUNET_new (struct TALER_MERCHANT_ProductLockHandle);
   plh->ctx = ctx;
   plh->cb = cb;
diff --git a/src/lib/merchant_api_patch_instance.c b/src/lib/merchant_api_patch_instance.c
index 74256330..5515e5e1 100644
--- a/src/lib/merchant_api_patch_instance.c
+++ b/src/lib/merchant_api_patch_instance.c
@@ -189,32 +189,25 @@ TALER_MERCHANT_instance_patch (
       return NULL;
     }
   }
-  req_obj = json_pack ("{s:o, s:s, s:O, s:O"
-                       " s:o, s:I: s:o, s:o, s:o}",
-                       "payto_uris",
-                       jpayto_uris,
-                       "name",
-                       name,
-                       "address",
-                       address,
-                       "jurisdiction",
-                       jurisdiction,
-                       /* end of group of 4 */
-                       "default_max_wire_fee",
-                       TALER_JSON_from_amount (default_max_wire_fee),
-                       "default_wire_fee_amortization",
-                       (json_int_t) default_wire_fee_amortization,
-                       "default_max_deposit_fee",
-                       TALER_JSON_from_amount (default_max_deposit_fee),
-                       "default_wire_transfer_delay",
-                       GNUNET_JSON_from_time_rel (default_wire_transfer_delay),
-                       "default_pay_delay",
-                       GNUNET_JSON_from_time_rel (default_pay_delay));
-  if (NULL == req_obj)
-  {
-    GNUNET_break (0);
-    return NULL;
-  }
+  req_obj = GNUNET_JSON_PACK (
+    GNUNET_JSON_pack_array_steal ("payto_uris",
+                                  jpayto_uris),
+    GNUNET_JSON_pack_string ("name",
+                             name),
+    GNUNET_JSON_pack_object_incref ("address",
+                                    (json_t *) address),
+    GNUNET_JSON_pack_object_incref ("jurisdiction",
+                                    (json_t *) jurisdiction),
+    TALER_JSON_pack_amount ("default_max_wire_fee",
+                            default_max_wire_fee),
+    GNUNET_JSON_pack_uint64 ("default_wire_fee_amortization",
+                             default_wire_fee_amortization),
+    TALER_JSON_pack_amount ("default_max_deposit_fee",
+                            default_max_deposit_fee),
+    GNUNET_JSON_pack_time_rel ("default_wire_transfer_delay",
+                               default_wire_transfer_delay),
+    GNUNET_JSON_pack_time_rel ("default_pay_delay",
+                               default_pay_delay));
   iph = GNUNET_new (struct TALER_MERCHANT_InstancePatchHandle);
   iph->ctx = ctx;
   iph->cb = cb;
diff --git a/src/lib/merchant_api_patch_order_forget.c b/src/lib/merchant_api_patch_order_forget.c
index 69563aaf..e6a36ad4 100644
--- a/src/lib/merchant_api_patch_order_forget.c
+++ b/src/lib/merchant_api_patch_order_forget.c
@@ -177,14 +177,9 @@ TALER_MERCHANT_order_forget (struct GNUNET_CURL_Context *ctx,
       return NULL;
     }
   }
-  req_obj = json_pack ("{s:o}",
-                       "fields",
-                       req_fields);
-  if (NULL == req_obj)
-  {
-    GNUNET_break (0);
-    return NULL;
-  }
+  req_obj = GNUNET_JSON_PACK (
+    GNUNET_JSON_pack_array_steal ("fields",
+                                  req_fields));
   ofh = GNUNET_new (struct TALER_MERCHANT_OrderForgetHandle);
   ofh->ctx = ctx;
   ofh->cb = cb;
diff --git a/src/lib/merchant_api_patch_product.c b/src/lib/merchant_api_patch_product.c
index 5cd1747e..da0e41ed 100644
--- a/src/lib/merchant_api_patch_product.c
+++ b/src/lib/merchant_api_patch_product.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  Copyright (C) 2020 Taler Systems SA
+  Copyright (C) 2020, 2021 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as
@@ -176,34 +176,27 @@ TALER_MERCHANT_product_patch (
   json_t *req_obj;
 
   (void) GNUNET_TIME_round_abs (&next_restock);
-  req_obj = json_pack ("{s:s, s:O, s:s, s:o, s:s,"
-                       " s:O, s:I: s:I, s:O, s:o}",
-                       "description",
-                       description,
-                       "description_i18n",
-                       description_i18n,
-                       "unit",
-                       unit,
-                       "price",
-                       TALER_JSON_from_amount (price),
-                       "image",
-                       image,
-                       /* End of first group of 5 */
-                       "taxes",
-                       taxes,
-                       "total_stock",
-                       (json_int_t) total_stock,
-                       "total_lost",
-                       (json_int_t) total_lost,
-                       "address",
-                       address,
-                       "next_restock",
-                       GNUNET_JSON_from_time_abs (next_restock));
-  if (NULL == req_obj)
-  {
-    GNUNET_break (0);
-    return NULL;
-  }
+  req_obj = GNUNET_JSON_PACK (
+    GNUNET_JSON_pack_string ("description",
+                             description),
+    GNUNET_JSON_pack_object_incref ("description_i18n",
+                                    (json_t *) description_i18n),
+    GNUNET_JSON_pack_string ("unit",
+                             unit),
+    TALER_JSON_pack_amount ("price",
+                            price),
+    GNUNET_JSON_pack_string ("image",
+                             image),
+    GNUNET_JSON_pack_array_incref ("taxes",
+                                   (json_t *) taxes),
+    GNUNET_JSON_pack_uint64 ("total_stock",
+                             total_stock),
+    GNUNET_JSON_pack_uint64 ("total_lost",
+                             total_lost),
+    GNUNET_JSON_pack_object_incref ("address",
+                                    (json_t *) address),
+    GNUNET_JSON_pack_time_abs ("next_restock",
+                               next_restock));
   pph = GNUNET_new (struct TALER_MERCHANT_ProductPatchHandle);
   pph->ctx = ctx;
   pph->cb = cb;
diff --git a/src/lib/merchant_api_post_instance_auth.c b/src/lib/merchant_api_post_instance_auth.c
index a659ffb5..bda209ee 100644
--- a/src/lib/merchant_api_post_instance_auth.c
+++ b/src/lib/merchant_api_post_instance_auth.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  Copyright (C) 2014-2018, 2020 Taler Systems SA
+  Copyright (C) 2014-2021 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify it under the
   terms of the GNU Lesser General Public License as published by the Free Software
@@ -168,24 +168,17 @@ TALER_MERCHANT_instance_auth_post (
   }
   if (NULL == auth_token)
   {
-    req_obj = json_pack ("{s:s}",
-                         "method",
-                         "external");
+    req_obj = GNUNET_JSON_PACK (
+      GNUNET_JSON_pack_string ("method",
+                               "external"));
   }
   else
   {
-    req_obj = json_pack ("{s:s, s:s}",
-                         "method",
-                         "token",
-                         "token",
-                         auth_token);
-  }
-  if (NULL == req_obj)
-  {
-    GNUNET_break (0);
-    GNUNET_free (iaph->url);
-    GNUNET_free (iaph);
-    return NULL;
+    req_obj = GNUNET_JSON_PACK (
+      GNUNET_JSON_pack_string ("method",
+                               "token"),
+      GNUNET_JSON_pack_string ("token",
+                               auth_token));
   }
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Requesting URL '%s'\n",
@@ -194,6 +187,7 @@ TALER_MERCHANT_instance_auth_post (
     CURL *eh;
 
     eh = curl_easy_init ();
+    GNUNET_assert (NULL != eh);
     if (GNUNET_OK !=
         TALER_curl_easy_post (&iaph->post_ctx,
                               eh,
diff --git a/src/lib/merchant_api_post_instances.c b/src/lib/merchant_api_post_instances.c
index 8aede243..6101e192 100644
--- a/src/lib/merchant_api_post_instances.c
+++ b/src/lib/merchant_api_post_instances.c
@@ -191,17 +191,17 @@ TALER_MERCHANT_instances_post (
                   RFC_8959_PREFIX);
       return NULL;
     }
-    auth_obj = json_pack ("{s:s, s:s}",
-                          "method",
-                          "token",
-                          "token",
-                          auth_token);
+    auth_obj = GNUNET_JSON_PACK (
+      GNUNET_JSON_pack_string ("method",
+                               "token"),
+      GNUNET_JSON_pack_string ("token",
+                               auth_token));
   }
   else
   {
-    auth_obj = json_pack ("{s:s}",
-                          "method",
-                          "external");
+    auth_obj = GNUNET_JSON_PACK (
+      GNUNET_JSON_pack_string ("method",
+                               "external"));
   }
   if (NULL == auth_obj)
   {
@@ -227,38 +227,29 @@ TALER_MERCHANT_instances_post (
       return NULL;
     }
   }
-  req_obj = json_pack ("{s:o, s:s, s:s, s:O, s:O"
-                       ",s:o, s:I: s:o, s:o, s:o"
-                       ",s:o}",
-                       "payto_uris",
-                       jpayto_uris,
-                       "id",
-                       instance_id,
-                       "name",
-                       name,
-                       "address",
-                       address,
-                       "jurisdiction",
-                       jurisdiction,
-                       /* end of group of 5 */
-                       "default_max_wire_fee",
-                       TALER_JSON_from_amount (default_max_wire_fee),
-                       "default_wire_fee_amortization",
-                       (json_int_t) default_wire_fee_amortization,
-                       "default_max_deposit_fee",
-                       TALER_JSON_from_amount (default_max_deposit_fee),
-                       "default_wire_transfer_delay",
-                       GNUNET_JSON_from_time_rel (default_wire_transfer_delay),
-                       "default_pay_delay",
-                       GNUNET_JSON_from_time_rel (default_pay_delay),
-                       "auth",
-                       auth_obj);
-  if (NULL == req_obj)
-  {
-    json_decref (auth_obj);
-    GNUNET_break (0);
-    return NULL;
-  }
+  req_obj = GNUNET_JSON_PACK (
+    GNUNET_JSON_pack_array_steal ("payto_uris",
+                                  jpayto_uris),
+    GNUNET_JSON_pack_string ("id",
+                             instance_id),
+    GNUNET_JSON_pack_string ("name",
+                             name),
+    GNUNET_JSON_pack_object_incref ("address",
+                                    (json_t *) address),
+    GNUNET_JSON_pack_object_incref ("jurisdiction",
+                                    (json_t *) jurisdiction),
+    TALER_JSON_pack_amount ("default_max_wire_fee",
+                            default_max_wire_fee),
+    GNUNET_JSON_pack_uint64 ("default_wire_fee_amortization",
+                             default_wire_fee_amortization),
+    TALER_JSON_pack_amount ("default_max_deposit_fee",
+                            default_max_deposit_fee),
+    GNUNET_JSON_pack_time_rel ("default_wire_transfer_delay",
+                               default_wire_transfer_delay),
+    GNUNET_JSON_pack_time_rel ("default_pay_delay",
+                               default_pay_delay),
+    GNUNET_JSON_pack_object_steal ("auth",
+                                   auth_obj));
   iph = GNUNET_new (struct TALER_MERCHANT_InstancesPostHandle);
   iph->ctx = ctx;
   iph->cb = cb;
diff --git a/src/lib/merchant_api_post_order_abort.c b/src/lib/merchant_api_post_order_abort.c
index f8cdaab4..47df8ec4 100644
--- a/src/lib/merchant_api_post_order_abort.c
+++ b/src/lib/merchant_api_post_order_abort.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  Copyright (C) 2014, 2015, 2016, 2017, 2020 Taler Systems SA
+  Copyright (C) 2014-2021 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as
@@ -348,34 +348,27 @@ TALER_MERCHANT_order_abort (struct GNUNET_CURL_Context *ctx,
     json_t *j_coin;
 
     /* create JSON for this coin */
-    j_coin = json_pack (
-      "{s:o, s:o,s:s}",
-      "coin_pub",
-      GNUNET_JSON_from_data_auto (&ac->coin_pub),
-      "contribution",
-      TALER_JSON_from_amount (&ac->amount_with_fee),
-      "exchange_url",
-      ac->exchange_url);
-    if ( (NULL == j_coin) ||
-         (0 !=
-          json_array_append_new (j_coins,
-                                 j_coin)) )
+    j_coin = GNUNET_JSON_PACK (
+      GNUNET_JSON_pack_data_auto ("coin_pub",
+                                  &ac->coin_pub),
+      TALER_JSON_pack_amount ("contribution",
+                              &ac->amount_with_fee),
+      GNUNET_JSON_pack_string ("exchange_url",
+                               ac->exchange_url));
+    if (0 !=
+        json_array_append_new (j_coins,
+                               j_coin))
     {
       GNUNET_break (0);
       json_decref (j_coins);
       return NULL;
     }
   }
-  abort_obj = json_pack ("{s:o,s:o}",
-                         "coins",
-                         j_coins, /* reference consumed! */
-                         "h_contract",
-                         GNUNET_JSON_from_data_auto (h_contract));
-  if (NULL == abort_obj)
-  {
-    GNUNET_break (0);
-    return NULL;
-  }
+  abort_obj = GNUNET_JSON_PACK (
+    GNUNET_JSON_pack_array_steal ("coins",
+                                  j_coins),
+    GNUNET_JSON_pack_data_auto ("h_contract",
+                                h_contract));
   oah = GNUNET_new (struct TALER_MERCHANT_OrderAbortHandle);
   oah->h_contract_terms = *h_contract;
   oah->merchant_pub = *merchant_pub;
diff --git a/src/lib/merchant_api_post_order_claim.c b/src/lib/merchant_api_post_order_claim.c
index 80c4949a..442185b5 100644
--- a/src/lib/merchant_api_post_order_claim.c
+++ b/src/lib/merchant_api_post_order_claim.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  Copyright (C) 2014-2020 Taler Systems SA
+  Copyright (C) 2014-2021 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as
@@ -182,22 +182,12 @@ TALER_MERCHANT_order_claim (struct GNUNET_CURL_Context *ctx,
     GNUNET_break (0);
     return NULL;
   }
-  req_obj = json_pack ("{s:o}",
-                       "nonce",
-                       GNUNET_JSON_from_data_auto (nonce));
-  if (NULL == req_obj)
-  {
-    GNUNET_break (0);
-    return NULL;
-  }
-  if (NULL != claim_token)
-  {
-    GNUNET_assert (0 ==
-                   json_object_set_new (req_obj,
-                                        "token",
-                                        GNUNET_JSON_from_data_auto (
-                                          claim_token)));
-  }
+  req_obj = GNUNET_JSON_PACK (
+    GNUNET_JSON_pack_data_auto ("nonce",
+                                nonce),
+    GNUNET_JSON_pack_allow_null (
+      GNUNET_JSON_pack_data_auto ("token",
+                                  claim_token)));
   och = GNUNET_new (struct TALER_MERCHANT_OrderClaimHandle);
   och->ctx = ctx;
   och->cb = cb;
diff --git a/src/lib/merchant_api_post_order_paid.c b/src/lib/merchant_api_post_order_paid.c
index cdb4ae23..cb3a8379 100644
--- a/src/lib/merchant_api_post_order_paid.c
+++ b/src/lib/merchant_api_post_order_paid.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  Copyright (C) 2020 Taler Systems SA
+  Copyright (C) 2020-2021 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as
@@ -173,18 +173,13 @@ TALER_MERCHANT_order_paid (
   struct TALER_MERCHANT_OrderPaidHandle *oph;
   json_t *req_obj;
 
-  req_obj = json_pack ("{s:o, s:o, s:s}",
-                       "sig",
-                       GNUNET_JSON_from_data_auto (merchant_sig),
-                       "h_contract",
-                       GNUNET_JSON_from_data_auto (h_contract_terms),
-                       "session_id",
-                       session_id);
-  if (NULL == req_obj)
-  {
-    GNUNET_break (0);
-    return NULL;
-  }
+  req_obj = GNUNET_JSON_PACK (
+    GNUNET_JSON_pack_data_auto ("sig",
+                                merchant_sig),
+    GNUNET_JSON_pack_data_auto ("h_contract",
+                                h_contract_terms),
+    GNUNET_JSON_pack_string ("session_id",
+                             session_id));
   oph = GNUNET_new (struct TALER_MERCHANT_OrderPaidHandle);
   oph->ctx = ctx;
   oph->paid_cb = paid_cb;
diff --git a/src/lib/merchant_api_post_order_pay.c b/src/lib/merchant_api_post_order_pay.c
index 8decd2b1..e5d8cb5e 100644
--- a/src/lib/merchant_api_post_order_pay.c
+++ b/src/lib/merchant_api_post_order_pay.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  Copyright (C) 2014, 2015, 2016, 2017, 2020 Taler Systems SA
+  Copyright (C) 2014-2021 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as
@@ -481,22 +481,19 @@ TALER_MERCHANT_order_pay_frontend (
     GNUNET_CRYPTO_rsa_public_key_hash (pc->denom_pub.rsa_public_key,
                                        &denom_hash);
     /* create JSON for this coin */
-    j_coin = json_pack (
-      "{s:o, s:o,"                   /* contribution/coin_pub */
-      " s:s, s:o,"          /* exchange_url / denom_pub */
-      " s:o, s:o}",          /* ub_sig / coin_sig */
-      "contribution",
-      TALER_JSON_from_amount (&pc->amount_with_fee),
-      "coin_pub",
-      GNUNET_JSON_from_data_auto (&pc->coin_pub),
-      "exchange_url",
-      pc->exchange_url,
-      "h_denom",
-      GNUNET_JSON_from_data_auto (&denom_hash),
-      "ub_sig",
-      GNUNET_JSON_from_rsa_signature (pc->denom_sig.rsa_signature),
-      "coin_sig",
-      GNUNET_JSON_from_data_auto (&pc->coin_sig));
+    j_coin = GNUNET_JSON_PACK (
+      TALER_JSON_pack_amount ("contribution",
+                              &pc->amount_with_fee),
+      GNUNET_JSON_pack_data_auto ("coin_pub",
+                                  &pc->coin_pub),
+      GNUNET_JSON_pack_string ("exchange_url",
+                               pc->exchange_url),
+      GNUNET_JSON_pack_data_auto ("h_denom",
+                                  &denom_hash),
+      TALER_JSON_pack_denomination_signature ("ub_sig",
+                                              &pc->denom_sig),
+      GNUNET_JSON_pack_data_auto ("coin_sig",
+                                  &pc->coin_sig));
     if (0 !=
         json_array_append_new (j_coins,
                                j_coin))
@@ -507,26 +504,12 @@ TALER_MERCHANT_order_pay_frontend (
     }
   }
 
-  pay_obj = json_pack ("{ s:o }",
-                       "coins",
-                       j_coins);
-  if (NULL == pay_obj)
-  {
-    GNUNET_break (0);
-    return NULL;
-  }
-  if (NULL != session_id)
-  {
-    if (0 !=
-        json_object_set_new (pay_obj,
-                             "session_id",
-                             json_string (session_id)))
-    {
-      GNUNET_break (0);
-      json_decref (pay_obj);
-      return NULL;
-    }
-  }
+  pay_obj = GNUNET_JSON_PACK (
+    GNUNET_JSON_pack_array_steal ("coins",
+                                  j_coins),
+    GNUNET_JSON_pack_allow_null (
+      GNUNET_JSON_pack_string ("session_id",
+                               session_id)));
 
   oph = GNUNET_new (struct TALER_MERCHANT_OrderPayHandle);
   oph->ctx = ctx;
diff --git a/src/lib/merchant_api_post_order_refund.c b/src/lib/merchant_api_post_order_refund.c
index 63ed2f2c..9829e187 100644
--- a/src/lib/merchant_api_post_order_refund.c
+++ b/src/lib/merchant_api_post_order_refund.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  Copyright (C) 2014, 2015, 2016, 2017, 2019, 2020 Taler Systems SA
+  Copyright (C) 2014-2021 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify it under the
   terms of the GNU Lesser General Public License as published by the Free Software
@@ -215,9 +215,11 @@ TALER_MERCHANT_post_order_refund (struct GNUNET_CURL_Context *ctx,
     GNUNET_free (orh);
     return NULL;
   }
-  req = json_pack ("{s:o, s:s}",
-                   "refund", TALER_JSON_from_amount (refund),
-                   "reason", reason);
+  req = GNUNET_JSON_PACK (
+    TALER_JSON_pack_amount ("refund",
+                            refund),
+    GNUNET_JSON_pack_string ("reason",
+                             reason));
   GNUNET_assert (NULL != req);
   eh = curl_easy_init ();
   GNUNET_assert (NULL != eh);
diff --git a/src/lib/merchant_api_post_orders.c b/src/lib/merchant_api_post_orders.c
index a79b9904..ae804ddf 100644
--- a/src/lib/merchant_api_post_orders.c
+++ b/src/lib/merchant_api_post_orders.c
@@ -260,9 +260,12 @@ TALER_MERCHANT_orders_post2 (
   po->url = TALER_url_join (backend_url,
                             "private/orders",
                             NULL);
-  req = json_pack ("{s:O}",
-                   "order", (json_t *) order);
-  GNUNET_assert (NULL != req);
+  req = GNUNET_JSON_PACK (
+    GNUNET_JSON_pack_object_incref ("order",
+                                    (json_t *) order),
+    GNUNET_JSON_pack_allow_null (
+      GNUNET_JSON_pack_string ("payment_target",
+                               payment_target)));
   if (0 != refund_delay.rel_value_us)
   {
     GNUNET_assert (0 ==
@@ -271,13 +274,6 @@ TALER_MERCHANT_orders_post2 (
                                         GNUNET_JSON_from_time_rel (
                                           refund_delay)));
   }
-  if (NULL != payment_target)
-  {
-    GNUNET_assert (0 ==
-                   json_object_set_new (req,
-                                        "payment_target",
-                                        json_string (payment_target)));
-  }
   if (0 != inventory_products_length)
   {
     json_t *ipa = json_array ();
@@ -287,11 +283,11 @@ TALER_MERCHANT_orders_post2 (
     {
       json_t *ip;
 
-      ip = json_pack ("{s:s, s:I}",
-                      "product_id",
-                      inventory_products[i].product_id,
-                      "quantity",
-                      (json_int_t) inventory_products[i].quantity);
+      ip = GNUNET_JSON_PACK (
+        GNUNET_JSON_pack_string ("product_id",
+                                 inventory_products[i].product_id),
+        GNUNET_JSON_pack_uint64 ("quantity",
+                                 inventory_products[i].quantity));
       GNUNET_assert (NULL != ip);
       GNUNET_assert (0 ==
                      json_array_append_new (ipa,
@@ -311,10 +307,9 @@ TALER_MERCHANT_orders_post2 (
     {
       json_t *u;
 
-      u = json_pack ("{s:o}",
-                     "uuid",
-                     GNUNET_JSON_from_data_auto (&uuids[i]));
-      GNUNET_assert (NULL != u);
+      u = GNUNET_JSON_PACK (
+        GNUNET_JSON_pack_data_auto ("uuid",
+                                    &uuids[i]));
       GNUNET_assert (0 ==
                      json_array_append_new (ua,
                                             u));
diff --git a/src/lib/merchant_api_post_products.c b/src/lib/merchant_api_post_products.c
index 5ef8b90e..c8aeb9c9 100644
--- a/src/lib/merchant_api_post_products.c
+++ b/src/lib/merchant_api_post_products.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  Copyright (C) 2020 Taler Systems SA
+  Copyright (C) 2020-2021 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as
@@ -177,34 +177,28 @@ TALER_MERCHANT_products_post (
   json_t *req_obj;
 
   (void) GNUNET_TIME_round_abs (&next_restock);
-  req_obj = json_pack ("{s:s, s:s, s:O, s:s, s:o,"
-                       " s:s, s:O, s:I, s:O, s:o}",
-                       "product_id",
-                       product_id,
-                       "description",
-                       description,
-                       "description_i18n",
-                       description_i18n,
-                       "unit",
-                       unit,
-                       "price",
-                       TALER_JSON_from_amount (price),
-                       /* End of first group of 5 */
-                       "image",
-                       image,
-                       "taxes",
-                       taxes,
-                       "total_stock",
-                       (json_int_t) total_stock,
-                       "address",
-                       address,
-                       "next_restock",
-                       GNUNET_JSON_from_time_abs (next_restock));
-  if (NULL == req_obj)
-  {
-    GNUNET_break (0);
-    return NULL;
-  }
+  req_obj = GNUNET_JSON_PACK (
+    GNUNET_JSON_pack_string ("product_id",
+                             product_id),
+    GNUNET_JSON_pack_string ("description",
+                             description),
+    GNUNET_JSON_pack_object_incref ("description_i18n",
+                                    (json_t *) description_i18n),
+    GNUNET_JSON_pack_string ("unit",
+                             unit),
+    TALER_JSON_pack_amount ("price",
+                            price),
+    GNUNET_JSON_pack_string ("image",
+                             image),
+    GNUNET_JSON_pack_array_incref ("taxes",
+                                   (json_t *) taxes),
+    GNUNET_JSON_pack_uint64 ("total_stock",
+                             total_stock),
+    GNUNET_JSON_pack_object_incref ("address",
+                                    (json_t *) address),
+    GNUNET_JSON_pack_allow_null (
+      GNUNET_JSON_pack_time_abs ("next_restock",
+                                 next_restock)));
   pph = GNUNET_new (struct TALER_MERCHANT_ProductsPostHandle);
   pph->ctx = ctx;
   pph->cb = cb;
diff --git a/src/lib/merchant_api_post_reserves.c b/src/lib/merchant_api_post_reserves.c
index 8a8dee2d..6957d480 100644
--- a/src/lib/merchant_api_post_reserves.c
+++ b/src/lib/merchant_api_post_reserves.c
@@ -197,11 +197,13 @@ TALER_MERCHANT_reserves_post (
     GNUNET_free (prh);
     return NULL;
   }
-  req = json_pack ("{s:o, s:s, s:s}",
-                   "initial_balance", TALER_JSON_from_amount (initial_balance),
-                   "wire_method", wire_method,
-                   "exchange_url", exchange_url);
-  GNUNET_assert (NULL != req);
+  req = GNUNET_JSON_PACK (
+    TALER_JSON_pack_amount ("initial_balance",
+                            initial_balance),
+    GNUNET_JSON_pack_string ("wire_method",
+                             wire_method),
+    GNUNET_JSON_pack_string ("exchange_url",
+                             exchange_url));
   eh = curl_easy_init ();
   GNUNET_assert (NULL != eh);
   if (GNUNET_OK != TALER_curl_easy_post (&prh->post_ctx,
diff --git a/src/lib/merchant_api_post_transfers.c b/src/lib/merchant_api_post_transfers.c
index 3e1a55d5..62984835 100644
--- a/src/lib/merchant_api_post_transfers.c
+++ b/src/lib/merchant_api_post_transfers.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  Copyright (C) 2014, 2015, 2016, 2020 Taler Systems SA
+  Copyright (C) 2014-2021 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify it under the
   terms of the GNU Lesser General Public License as published by the Free Software
@@ -104,9 +104,9 @@ handle_post_transfers_finished (void *cls,
       json_t *deposit_sums;
       struct GNUNET_JSON_Specification spec[] = {
         TALER_JSON_spec_amount_any ("total",
-                                &total),
+                                    &total),
         TALER_JSON_spec_amount_any ("wire_fee",
-                                &wire_fee),
+                                    &wire_fee),
         TALER_JSON_spec_absolute_time ("execution_time",
                                        &execution_time),
         GNUNET_JSON_spec_json ("deposit_sums",
@@ -149,9 +149,9 @@ handle_post_transfers_finished (void *cls,
             GNUNET_JSON_spec_string ("order_id",
                                      &d->order_id),
             TALER_JSON_spec_amount_any ("deposit_value",
-                                    &d->deposit_value),
+                                        &d->deposit_value),
             TALER_JSON_spec_amount_any ("deposit_fee",
-                                    &d->deposit_fee),
+                                        &d->deposit_fee),
             GNUNET_JSON_spec_end ()
           };
 
@@ -300,12 +300,15 @@ TALER_MERCHANT_transfers_post (
     GNUNET_free (pth);
     return NULL;
   }
-  req = json_pack ("{s:o, s:o, s:s, s:s}",
-                   "credit_amount", TALER_JSON_from_amount (credit_amount),
-                   "wtid", GNUNET_JSON_from_data_auto (wtid),
-                   "payto_uri", payto_uri,
-                   "exchange_url", exchange_url);
-  GNUNET_assert (NULL != req);
+  req = GNUNET_JSON_PACK (
+    TALER_JSON_pack_amount ("credit_amount",
+                            credit_amount),
+    GNUNET_JSON_pack_data_auto ("wtid",
+                                wtid),
+    GNUNET_JSON_pack_string ("payto_uri",
+                             payto_uri),
+    GNUNET_JSON_pack_string ("exchange_url",
+                             exchange_url));
   eh = curl_easy_init ();
   GNUNET_assert (NULL != eh);
   if (GNUNET_OK != TALER_curl_easy_post (&pth->post_ctx,
diff --git a/src/lib/merchant_api_tip_authorize.c b/src/lib/merchant_api_tip_authorize.c
index d45f61a9..0a9c3d86 100644
--- a/src/lib/merchant_api_tip_authorize.c
+++ b/src/lib/merchant_api_tip_authorize.c
@@ -256,26 +256,19 @@ TALER_MERCHANT_tip_authorize2 (
     GNUNET_free (tao);
     return NULL;
   }
-  te_obj = json_pack ("{"
-                      " s:o," /* amount */
-                      " s:s," /* justification */
-                      " s:s," /* next_url */
-                      "}",
-                      "amount", TALER_JSON_from_amount (amount),
-                      "justification", justification,
-                      "next_url", next_url);
-  if (NULL == te_obj)
-  {
-    GNUNET_break (0);
-    GNUNET_free (tao->url);
-    GNUNET_free (tao);
-    return NULL;
-  }
-
+  te_obj = GNUNET_JSON_PACK (
+    TALER_JSON_pack_amount ("amount",
+                            amount),
+    GNUNET_JSON_pack_string ("justification",
+                             justification),
+    GNUNET_JSON_pack_string ("next_url",
+                             next_url));
   eh = curl_easy_init ();
-  if (GNUNET_OK != TALER_curl_easy_post (&tao->post_ctx,
-                                         eh,
-                                         te_obj))
+  GNUNET_assert (NULL != eh);
+  if (GNUNET_OK !=
+      TALER_curl_easy_post (&tao->post_ctx,
+                            eh,
+                            te_obj))
   {
     GNUNET_break (0);
     json_decref (te_obj);
@@ -329,23 +322,15 @@ TALER_MERCHANT_tip_authorize (struct GNUNET_CURL_Context *ctx,
     GNUNET_free (tao);
     return NULL;
   }
-  te_obj = json_pack ("{"
-                      " s:o," /* amount */
-                      " s:s," /* justification */
-                      " s:s," /* next_url */
-                      "}",
-                      "amount", TALER_JSON_from_amount (amount),
-                      "justification", justification,
-                      "next_url", next_url);
-  if (NULL == te_obj)
-  {
-    GNUNET_break (0);
-    GNUNET_free (tao->url);
-    GNUNET_free (tao);
-    return NULL;
-  }
-
+  te_obj = GNUNET_JSON_PACK (
+    TALER_JSON_pack_amount ("amount",
+                            amount),
+    GNUNET_JSON_pack_string ("justification",
+                             justification),
+    GNUNET_JSON_pack_string ("next_url",
+                             next_url));
   eh = curl_easy_init ();
+  GNUNET_assert (NULL != eh);
   if (GNUNET_OK != TALER_curl_easy_post (&tao->post_ctx,
                                          eh,
                                          te_obj))
diff --git a/src/lib/merchant_api_tip_pickup2.c b/src/lib/merchant_api_tip_pickup2.c
index 9b6c4eff..38ad77d8 100644
--- a/src/lib/merchant_api_tip_pickup2.c
+++ b/src/lib/merchant_api_tip_pickup2.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  Copyright (C) 2014-2017, 2020 Taler Systems SA
+  Copyright (C) 2014-2021 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify it under the
   terms of the GNU Lesser General Public License as published by the Free Software
@@ -254,22 +254,12 @@ TALER_MERCHANT_tip_pickup2 (struct GNUNET_CURL_Context *ctx,
     const struct TALER_PlanchetDetail *planchet = &planchets[i];
     json_t *p;
 
-    p = json_pack ("{"
-                   " s:o," /* denom_pub_hash */
-                   " s:o," /* coin_ev */
-                   "}",
-                   "denom_pub_hash",
-                   GNUNET_JSON_from_data_auto (
-                     &planchet->denom_pub_hash),
-                   "coin_ev",
-                   GNUNET_JSON_from_data (planchet->coin_ev,
-                                          planchet->coin_ev_size));
-    if (NULL == p)
-    {
-      GNUNET_break (0);
-      json_decref (pa);
-      return NULL;
-    }
+    p = GNUNET_JSON_PACK (
+      GNUNET_JSON_pack_data_auto ("denom_pub_hash",
+                                  &planchet->denom_pub_hash),
+      GNUNET_JSON_pack_data_varsize ("coin_ev",
+                                     planchet->coin_ev,
+                                     planchet->coin_ev_size));
     if (0 !=
         json_array_append_new (pa,
                                p))
@@ -279,14 +269,9 @@ TALER_MERCHANT_tip_pickup2 (struct GNUNET_CURL_Context *ctx,
       return NULL;
     }
   }
-  tp_obj = json_pack ("{s:o}",
-                      "planchets",
-                      pa);
-  if (NULL == tp_obj)
-  {
-    GNUNET_break (0);
-    return NULL;
-  }
+  tp_obj = GNUNET_JSON_PACK (
+    GNUNET_JSON_pack_array_steal ("planchets",
+                                  pa));
   tpo = GNUNET_new (struct TALER_MERCHANT_TipPickup2Handle);
   tpo->num_planchets = num_planchets;
   tpo->ctx = ctx;
diff --git a/src/lib/merchant_api_wallet_post_order_refund.c b/src/lib/merchant_api_wallet_post_order_refund.c
index ff19b09e..e2438cba 100644
--- a/src/lib/merchant_api_wallet_post_order_refund.c
+++ b/src/lib/merchant_api_wallet_post_order_refund.c
@@ -135,7 +135,7 @@ handle_refund_finished (void *cls,
       unsigned int refund_len;
       struct GNUNET_JSON_Specification spec[] = {
         TALER_JSON_spec_amount_any ("refund_amount",
-                                &refund_amount),
+                                    &refund_amount),
         GNUNET_JSON_spec_json ("refunds",
                                &refunds),
         GNUNET_JSON_spec_fixed_auto ("merchant_pub",
@@ -215,7 +215,7 @@ handle_refund_finished (void *cls,
               GNUNET_JSON_spec_fixed_auto ("coin_pub",
                                            &rd->coin_pub),
               TALER_JSON_spec_amount_any ("refund_amount",
-                                      &rd->refund_amount),
+                                          &rd->refund_amount),
               GNUNET_JSON_spec_end ()
             };
 
@@ -242,7 +242,7 @@ handle_refund_finished (void *cls,
               GNUNET_JSON_spec_uint64 ("rtransaction_id",
                                        &rd->rtransaction_id),
               TALER_JSON_spec_amount_any ("refund_amount",
-                                      &rd->refund_amount),
+                                          &rd->refund_amount),
               GNUNET_JSON_spec_end ()
             };
 
@@ -378,10 +378,9 @@ TALER_MERCHANT_wallet_post_order_refund (
     GNUNET_free (orh);
     return NULL;
   }
-  req = json_pack ("{s:o}",
-                   "h_contract",
-                   GNUNET_JSON_from_data_auto (h_contract_terms));
-  GNUNET_assert (NULL != req);
+  req = GNUNET_JSON_PACK (
+    GNUNET_JSON_pack_data_auto ("h_contract",
+                                h_contract_terms));
   eh = curl_easy_init ();
   GNUNET_assert (NULL != eh);
   if (GNUNET_OK !=