Begin/end balance stat graph

- Anytime begin at account creation datetime
- Others doesn't take care of account creation
- Add check to avoid to bug on actions list length

kfet/views.py

@@ -2186,7 +2186,22 @@ class AccountStatBalance(PkUrlMixin, JSONDetailView):
         #                                      autre passe)
         # }
 
-        actions = [
+        actions = []
+
+        actions.append({
+            'at': (begin_date or account.created_at).isoformat(),
+            'amount': 0,
+            'label': 'début',
+            'balance': 0,
+        })
+        actions.append({
+            'at': (end_date or timezone.now()).isoformat(),
+            'amount': 0,
+            'label': 'fin',
+            'balance': 0,
+        })
+
+        actions += [
             {
                 'at': ope_grp.at.isoformat(),
                 'amount': ope_grp.amount,
@@ -2210,11 +2225,12 @@ class AccountStatBalance(PkUrlMixin, JSONDetailView):
         ]
         # Maintenant on trie la liste des actions par ordre du plus récent
         # an plus ancien et on met à jour la balance
-        actions = sorted(actions, key=lambda k: k['at'], reverse=True)
-        actions[0]['balance'] = account.balance
-        for i in range(len(actions)-1):
-            actions[i+1]['balance'] = \
-                    actions[i]['balance'] - actions[i+1]['amount']
+        if len(actions) > 1:
+            actions = sorted(actions, key=lambda k: k['at'], reverse=True)
+            actions[0]['balance'] = account.balance
+            for i in range(len(actions)-1):
+                actions[i+1]['balance'] = \
+                        actions[i]['balance'] - actions[i+1]['amount']
         return actions
 
     def get_context_data(self, *args, **kwargs):