我正在尝试使用 Flask、SQLAlchemy 和 Marshmallow 在 Python 3.4 中构建一个 REST API 应用程序。
在我的模型中,我有一个User
类与一个类具有一对多关系MailAddress
。
如果我运行一个GET
请求,我会设法从数据库中读取数据,并且数据会以 JSON 字符串的形式正确返回。
相反,如果我使用 some 对我的对象进行POST
JSON 序列化来运行请求,我会收到以下错误:User
MailAddresses
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'
我尝试向__hash__
我的模型类中添加一个函数(如sqlalchemy: TypeError: unhashable type Creating instance, sqlalchemy所建议的那样),但这并没有帮助。
这是显示此问题的完整代码示例:
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)
有什么我想念的吗?