I'm trying to build a REST API application in Python 3.4, using Flask, SQLAlchemy and Marshmallow.
In my model I have a User class with a one to many relationship with a MailAddress class.
If I run a GET request, I manage to read data from the DB, and the data is correctly returned as a JSON string.
Instead, if I run a POST request with the JSON serialization of my User object with some MailAddresses, I get this error:
File "X:\test\...\site-packages\sqlalchemy\orm\collections.py", line 785, in bulk_replace
constants = existing_idset.intersection(values or ())
File "X:\test\...\site-packages\sqlalchemy\util\_collections.py", line 612, in intersection
result._members.update(self._working_set(members).intersection(other))
TypeError: unhashable type: 'dict'
I've tried adding a __hash__ function to my model classes (as suggested at sqlalchemy: TypeError: unhashable type creating instance, sqlalchemy) but that didn't help.
Here is a complete code example that shows this problem:
from flask import Flask, request
from flask_marshmallow import Marshmallow
from flask_sqlalchemy import SQLAlchemy
from marshmallow import fields
from sqlalchemy import Table, Column, Integer, String, ForeignKey
from sqlalchemy.orm import relationship
class Config(object):
SQLALCHEMY_DATABASE_URI = '<CONNECTION STRING HERE>'
SQLALCHEMY_TRACK_MODIFICATIONS = False
app = Flask(__name__)
app.config.from_object(Config)
db = SQLAlchemy(app)
ma = Marshmallow(app)
# Model
class MailAddress(db.Model):
__tablename__ = 'mail_addresses'
id = Column(Integer, primary_key=True)
user_id = Column(Integer, ForeignKey('users.id'))
mail_type = Column(String(200), nullable=False)
mail = Column(String(200), nullable=False)
def __init__(self, mail, mail_type):
self.mail = mail
self.mail_type = mail_type
class MailAddressSchema(ma.ModelSchema):
class Meta:
model = MailAddress
class User(db.Model):
__tablename__ = 'users'
id = Column(Integer, primary_key=True)
name = Column(String(200), nullable=False)
mail_addresses = relationship('MailAddress', backref='user')
def __init__(self, name, mail_addresses):
self.name = name
self.mail_addresses = mail_addresses
def __hash__(self):
return hash(self.name)
class UserSchema(ma.ModelSchema):
mail_addresses = fields.Nested(MailAddressSchema, many = True, only=('mail', 'mail_type'))
class Meta:
model = User
# Routes
user_schema = UserSchema()
@app.route('/api/v0/user', methods=['GET'])
def user_get():
users = db.session.query(User).all()
return user_schema.jsonify(users, many = True), 200
@app.route('/api/v0/user', methods=['POST'])
def user_create():
new_instance = user_schema.make_instance(request.json)
db.session.add(new_instance)
db.session.commit()
return user_schema.jsonify(new_instance), 201
# Main
if __name__ == '__main__':
app.run('localhost', 5555)
Is there something I'm missing?
