Correctly compute running totals in account transactions view

Fixes #4

drcr/models.py

@@ -111,6 +111,9 @@ class Amount:
 	def __sub__(self, other):
 		return self + (-other)
 	
+	def clone(self):
+		return Amount(self.quantity, self.commodity)
+	
 	def format(self, commodity='non_reporting'):
 		if commodity not in ('non_reporting', 'force', 'hide'):
 			raise ValueError('Invalid commodity reporting option')
@@ -168,6 +171,11 @@ class Balance:
 	def __init__(self):
 		self.amounts = []
 	
+	def clone(self):
+		balance = Balance()
+		balance.amounts = [a.clone() for a in self.amounts]
+		return balance
+	
 	def add(self, rhs):
 		amount = next((a for a in self.amounts if a.commodity == rhs.commodity), None)
 		if amount is None:

drcr/templates/transactions.html

@@ -1,5 +1,5 @@
 {#  DrCr: Web-based double-entry bookkeeping framework
-    Copyright (C) 2022  Lee Yingtong Li (RunasSudo)
+    Copyright (C) 2022–2024  Lee Yingtong Li (RunasSudo)
 
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU Affero General Public License as published by
@@ -42,7 +42,6 @@
 			{% for transaction in transactions %}
 				{% if transaction.postings|length == 2 %}
 					{% for posting in transaction.postings if posting.account == account %}
-						{% set _ = running_total.__setattr__('quantity', running_total.quantity + posting.amount().as_cost().quantity) %}
 						<tr>
 							<td>{{ transaction.dt.strftime('%Y-%m-%d') }}</td>
 							<td>
@@ -52,8 +51,8 @@
 							<td>{% for p in transaction.postings if p.account != account %}{{ p.account }}{% endfor %}</td>
 							<td class="text-end">{{ posting.amount().as_cost().format() if posting.quantity >= 0 else '' }}</td>
 							<td class="text-end">{{ (posting.amount()|abs).as_cost().format() if posting.quantity < 0 else '' }}</td>
-							<td class="text-end">{{ (running_total|abs).format() }}</td>
+							<td class="text-end">{{ (running_totals[posting]|abs).format() }}</td>
-							<td>{{ 'Dr' if running_total.quantity >= 0 else 'Cr' }}</td>
+							<td>{{ 'Dr' if running_totals[posting].quantity >= 0 else 'Cr' }}</td>
 						</tr>
 					{% endfor %}
 				{% else %}
@@ -69,15 +68,14 @@
 						<td></td>
 					</tr>
 					{% for posting in transaction.postings if posting.account == account %}
-						{% set _ = running_total.__setattr__('quantity', running_total.quantity + posting.amount().as_cost().quantity) %}
 						<tr>
 							<td></td>
 							<td class="text-end"><i>{{ 'Dr' if posting.quantity >= 0 else 'Cr' }}</i></td>
 							<td>{{ account }}</td>
 							<td class="text-end">{{ posting.amount().as_cost().format() if posting.quantity >= 0 else '' }}</td>
 							<td class="text-end">{{ (posting.amount()|abs).as_cost().format() if posting.quantity < 0 else '' }}</td>
-							<td class="text-end">{{ (running_total|abs).format() }}</td>
+							<td class="text-end">{{ (running_totals[posting]|abs).format() }}</td>
-							<td>{{ 'Dr' if running_total.quantity >= 0 else 'Cr' }}</td>
+							<td>{{ 'Dr' if running_totals[posting].quantity >= 0 else 'Cr' }}</td>
 						</tr>
 					{% endfor %}
 					{% for posting in transaction.postings if posting.account != account %}

drcr/templates/transactions_commodity_detail.html

@@ -1,5 +1,5 @@
 {#  DrCr: Web-based double-entry bookkeeping framework
-    Copyright (C) 2022–2023  Lee Yingtong Li (RunasSudo)
+    Copyright (C) 2022–2024  Lee Yingtong Li (RunasSudo)
 
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU Affero General Public License as published by
@@ -49,10 +49,7 @@
 					<td></td>
 					<td></td>
 				</tr>
-				{% for posting in transaction.postings if posting.account == account %}
+				{% for amount in running_totals[transaction].amounts %}
-					{% set _ = running_total.add(posting.amount()) %}
-				{% endfor %}
-				{% for amount in running_total.amounts %}
 					{# FIXME: Assumes at most one posting per commodity #}
 					{% for posting in transaction.postings if posting.commodity == amount.commodity and posting.account == account %}
 						<tr>
@@ -74,7 +71,6 @@
 						</tr>
 					{% endfor %}
 				{% endfor %}
-				{% set _ = running_total.clean() %}
 			{% endfor %}
 		</tbody>
 	</table>

drcr/views.py

@@ -83,17 +83,39 @@ def account_transactions():
 	transactions = [t for t in all_transactions() if any(p.account == request.args['account'] for p in t.postings)]
 	
 	if request.args.get('commodity_detail', '0') == '1':
+		# Pre-compute running totals
+		# At the level of individual transactions
+		running_totals = {}
+		running_total = Balance()
+		for transaction in sorted(transactions, key=lambda t: t.dt):
+			for posting in transaction.postings:
+				if posting.account == request.args['account']:
+					running_total.add(posting.amount())
+			
+			running_totals[transaction] = running_total.clone()
+			running_total.clean()
+		
 		return render_template(
 			'transactions_commodity_detail.html',
 			account=request.args['account'],
-			running_total=Balance(),
+			running_totals=running_totals,
 			transactions=reversed(sorted(transactions, key=lambda t: t.dt))
 		)
 	else:
+		# Pre-compute running totals
+		# There can be more than one posting per account per transaction, so track the running total at the level of individual postings
+		running_totals = {}
+		running_total = Amount(0, '$')
+		for transaction in sorted(transactions, key=lambda t: t.dt):
+			for posting in transaction.postings:
+				if posting.account == request.args['account']:
+					running_total += posting.amount().as_cost()
+					running_totals[posting] = running_total
+		
 		return render_template(
 			'transactions.html',
 			account=request.args['account'],
-			running_total=Amount(0, '$'),
+			running_totals=running_totals,
 			transactions=reversed(sorted(transactions, key=lambda t: t.dt))
 		)