Adding balance to ledger record

api/app/ledger/resource.py

@@ -1,4 +1,4 @@
-from sqlalchemy import and_, select
+from sqlalchemy import and_, select, func
 from sqlalchemy.orm import aliased
 
 from ledger.schema import TransactionLedgerRead
@@ -10,10 +10,18 @@ class LedgerResource:
     @classmethod
     def get_ledger(cls, session, account_id):
         split_account = aliased(Split)
+        split_balance = aliased(Split)
+        transaction_balance = aliased(Transaction)
 
-        stmt = select(Transaction, split_account).join(
+        balance_stmt = select(func.sum(split_balance.amount)).join(transaction_balance).where(and_(split_balance.account_id == split_account.account_id, transaction_balance.sequence <= Transaction.sequence)).scalar_subquery()
+
+        stmt = (select(
+            Transaction,
+            split_account,
+            balance_stmt.label('balance')
+        ).join(
             split_account,
             and_(Transaction.id == split_account.transaction_id, split_account.account_id == account_id)
-        )
+        ))
 
-        return [TransactionLedgerRead(transaction=transaction, account_split=split) for transaction, split in session.exec(stmt).all()]
+        return [TransactionLedgerRead(transaction=transaction, account_split=split, balance=balance) for transaction, split, balance in session.exec(stmt).all()]

api/app/ledger/schema.py

@@ -1,3 +1,5 @@
+import decimal
+
 from pydantic import BaseModel, Field
 
 from transaction.models import TransactionRead, SplitRead
@@ -5,3 +7,4 @@ from transaction.models import TransactionRead, SplitRead
 class TransactionLedgerRead(BaseModel):
     transaction: TransactionRead = Field()
     account_split: SplitRead = Field()
+    balance: decimal.Decimal = Field()

api/app/transaction/fixtures.py

@@ -22,7 +22,7 @@ def prepare_dict(session, entry, iteration):
     result["payee_id"] = None
     result["splits"] = []
     result["transaction_date"] = entry["start_date"] + timedelta(days=(iteration / 2))
-    result["amount"] = ["10", "100", "1000"][random.Random().randint(0,2)]
+    result["amount"] = [10, 100, 1000][random.Random().randint(0,2)] * [1, -1][random.Random().randint(0,1)]
     result["id"] = 0
 
     return result