bitvend/models: turn user balance into column_property

bitvend/models.py

@@ -2,6 +2,7 @@ from flask import current_app as app
 from flask_sqlalchemy import SQLAlchemy
 from datetime import datetime
 
+from sqlalchemy.orm import column_property
 from sqlalchemy.ext.hybrid import hybrid_property
 from sqlalchemy.sql import func, select, and_
 
@@ -16,6 +17,41 @@ class NoFunds(TransferException):
     pass
 
 
+class Transaction(db.Model):
+    __tablename__ = "transactions"
+
+    id = db.Column(db.Integer, primary_key=True)
+    tx_hash = db.Column(db.String)
+    uid = db.Column(db.String(64), db.ForeignKey("users.uid"))
+
+    amount = db.Column(db.Integer)
+
+    type = db.Column(db.String(32), default="manual")
+
+    related = db.Column(db.String)
+    related_user = db.relationship(
+        "User", foreign_keys=[related], primaryjoin="Transaction.related == User.uid"
+    )
+
+    created = db.Column(db.DateTime, default=datetime.utcnow, nullable=False)
+
+    @hybrid_property
+    def value(self):
+        return self.amount
+
+    product_id = db.Column(db.Integer)
+    product_value = db.Column(db.Integer)
+
+    @hybrid_property
+    def finished(self):
+        return (self.type != "purchase") | (self.product_id != None)
+
+    __mapper_args__ = {"order_by": created.desc()}
+
+    def __repr__(self):
+        return "<Transaction {0.uid} {0.type} {0.amount} {0.created}>".format(self)
+
+
 class User(db.Model):
     __tablename__ = "users"
 
@@ -28,17 +64,11 @@ class User(db.Model):
     def __repr__(self):
         return "<User {0.uid} {0.balance}>".format(self)
 
-    @hybrid_property
-    def balance(self):
-        return sum((_.amount or 0) for _ in self.transactions)
-
-    @balance.expression
-    def balance(self):
-        return (
-            select([func.sum(Transaction.amount)])
-            .where(Transaction.uid == User.uid)
-            .label("balance")
-        )
+    balance = column_property(
+        select([func.sum(Transaction.amount)])
+        .where(Transaction.uid == uid)
+        .correlate_except(Transaction)
+    )
 
     @hybrid_property
     def purchase_count(self):
@@ -100,39 +130,3 @@ class User(db.Model):
     @classmethod
     def find(cls, uid):
         return cls.query.filter(func.lower(cls.uid) == func.lower(uid)).first()
-
-
-class Transaction(db.Model):
-    __tablename__ = "transactions"
-
-    id = db.Column(db.Integer, primary_key=True)
-    tx_hash = db.Column(db.String)
-    uid = db.Column(db.String(64), db.ForeignKey("users.uid"))
-
-    amount = db.Column(db.Integer)
-
-    type = db.Column(db.String(32), default="manual")
-
-    related = db.Column(db.String)
-    related_user = db.relationship(
-        "User", foreign_keys=[related], primaryjoin=related == User.uid
-    )
-
-    created = db.Column(db.DateTime, default=datetime.utcnow, nullable=False)
-
-    # value = db.Column(db.Integer)
-    @hybrid_property
-    def value(self):
-        return self.amount
-
-    product_id = db.Column(db.Integer)
-    product_value = db.Column(db.Integer)
-
-    @hybrid_property
-    def finished(self):
-        return (self.type != "purchase") | (self.product_id != None)
-
-    __mapper_args__ = {"order_by": created.desc()}
-
-    def __repr__(self):
-        return "<Transaction {0.uid} {0.type} {0.amount} {0.created}>".format(self)