how to perform join query with sql alchemy with postgres - postgresql

Question

ExpenseList table have two foreign keys, i want to fetch list of expenses from this category with corresponding category. Currently it is returning category_id only when i am applying following query:
query = ExpenseList.query.filter_by(user_id=6)
return make_response(jsonify([i.serialize for i in query.all()])),200
Its returning response like this:
[
{
"category": 3,
"created_on": "Sun, 05 Nov 2017 09:40:19 GMT",
"money_spent": "50",
"name": "DVD"
},
{
"category": 3,
"created_on": "Sun, 05 Nov 2017 09:40:39 GMT",
"money_spent": "100",
"name": "Movie"
}
]
Model schema is
class ExpenseList(db.Model):
__tablename__ = 'expense_list'
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
name = db.Column(db.String(500), unique=True, nullable=False)
money_spent = db.Column(db.String(500), nullable=False)
category_id = db.Column(db.Integer, db.ForeignKey('category_list.id'))
user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
is_recurring = db.Column(db.Boolean,nullable=False, default=False)
created_on = db.Column(db.DateTime, nullable=False)
#property
def serialize(self):
return {
'name' : self.name,
'money_spent' : self.money_spent,
'category' : self.category_id,
'created_on' : self.created_on
}
class CategoryList(db.Model):
__tablename__ = 'category_list'
id = db.Column(db.Integer,primary_key = True, autoincrement=True)
name = db.Column(db.String(500), unique=True, autoincrement=True)
user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
created_on = db.Column(db.DateTime, nullable=False)
How can i get category name instead of category_id in response object, I also tried backrefs, lazy etc but don't know where i am going wrong.

Answer 1

Here is a join You want
query(ExpenseList.name.label('expense_name'),
ExpenseList.money_spent,
CategoryList.name.label('category_name'),
ExpenseList.created_on)\
.join(CategoryList, ExpenseList.category_id == CategoryList.id)\
.filter_by(ExpenseList.user_id=6)
and a worrying part in Your CategoryList model is:
name = db.Column(db.String(500), unique=True, autoincrement=True)