Paginator.

Do not use 'start_row' anymore when retrieving
pages higher than number 1.  Rather, get all the
previous records and discard those already seen.

Although a bit wasteful, this simplifies a
lot the calculation of the first row to be seen
on the next page.  And possibly not more wasteful
than calculating the last row for each page.

1 files changed, 9 insertions, 8 deletions

diff --git a/talerbank/app/views.py b/talerbank/app/views.py
index e0c3ed4..6a09edf 100644
--- a/talerbank/app/views.py
+++ b/talerbank/app/views.py
@@ -352,7 +352,9 @@ def extract_history(account, delta=None, start=-1, sign="+"):
 
 def serve_public_accounts(request, name=None, page=None):
     try:
-        page = int(page)
+        page = abs(int(page))
+        if page == 0:
+            raise Exception
     except Exception:
         page = 1
 
@@ -364,20 +366,19 @@ def serve_public_accounts(request, name=None, page=None):
 
     num_records = query_history_raw(user.bankaccount,
                                     "both",
-                                    start=-1,
-                                    sign="-").count()
+                                    start=-1, # makes sign ignored.
+                                    sign="+").count()
     DELTA = 30
     # '//' operator is NO floating point.
     num_pages = max(num_records // DELTA, 1)
-    start_row = 1 + (DELTA * (page - 1))
 
     public_accounts = BankAccount.objects.filter(is_public=True)
 
     # Retrieve DELTA records younger than 'start_row' (included).
     history = extract_history(user.bankaccount,
-                              DELTA,
-                              start_row - 1,
-                              "+") # takes results youger than 'start_row'
+                              DELTA * page,
+                              -1,
+                              "+")[DELTA * (page - 1):(DELTA * page)]
 
     pages = list(range(1, num_pages + 1))
 
@@ -444,7 +445,7 @@ def query_history_raw(bank_account, direction, start, sign):
     }
 
     # Handle special case.
-    if start == -1: # return 'delta' youngest records.
+    if start < 0: # return all the records.
         sign = "+"
 
     return BankTransaction.objects.filter(