update pay function

app.py

@@ -4633,7 +4633,7 @@ class PredictionTransaction(db.Model):
     topic_id = db.Column(db.Integer, db.ForeignKey('prediction_topic.id'), nullable=False)
 
     # 交易信息
-    transaction_type = db.Column(db.String(10), nullable=False)  # buy/sell
+    trade_type = db.Column(db.String(10), nullable=False)  # buy/sell
     direction = db.Column(db.String(3), nullable=False)  # yes/no
     shares = db.Column(db.Integer, nullable=False)  # 份额数量
     price = db.Column(db.Float, nullable=False)  # 成交价格
@@ -4650,7 +4650,7 @@ class PredictionTransaction(db.Model):
     user = db.relationship('User', backref='prediction_transactions')
 
     def __repr__(self):
-        return f'<PredictionTransaction id={self.id} type={self.transaction_type} shares={self.shares}>'
+        return f'<PredictionTransaction id={self.id} type={self.trade_type} shares={self.shares}>'
 
 
 class CreditTransaction(db.Model):
@@ -13987,7 +13987,7 @@ def buy_prediction_shares():
         transaction = PredictionTransaction(
             user_id=current_user.id,
             topic_id=topic_id,
-            transaction_type='buy',
+            trade_type='buy',
             direction=direction,
             shares=shares,
             price=avg_price,