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python - sqlalchemy.orm.exc.UnmappedInstanceError : Class 'builtins.dict' is not mapped

转载 作者:行者123 更新时间:2023-12-05 01:36:36 32 4
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我正在尝试使用 SQLAlchemy 和 Marshmallow 将新用户插入到数据库中。 user 参数是从 API 端点接收的。一切正常,直到我到达 create 函数中的这一行:

db.session.add(new_user)

此时 new_user 变量的值为:

{'password': 'string', 'email': 'fave@string', 'username': 'string'}

功能:

def create(user):
uname = user.get('username')
email = user.get('email')
password = user.get ('password')

existing_username = User.query.filter(User.username == uname).one_or_none()

if existing_username is None:

schema = UserSchema()
new_user = schema.load(user, session=db.session)

db.session.add(new_user) <- It fails here
db.session.commit()

return schema.dump(new_user), 201

模型:

    class User (db.Model):
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(20), unique=True, nullable=False)
email = db.Column(db.String(120), unique=True, nullable=False)
profile_picture = db.Column(db.String(20), nullable=False, default='default.jpg')
password = db.Column(db.String(60), nullable=False)
creation_date = db.Column(db.DateTime(120), nullable=False, default=datetime.utcnow)
updated_date = db.Column(db.DateTime(120), nullable=False, default=datetime.utcnow, onupdate=datetime.utcnow)
posts = db.relationship('Post', backref='author', lazy=True)

def __repr__(self):
return f"User ('{self.username}','{self.email}','{self.profile_picture}') "
    class Post (db.Model):
id = db.Column(db.Integer, primary_key=True)
title = db.Column(db.String(100), nullable=False)
date_posted = db.Column(db.DateTime(120), nullable=False, default=datetime.utcnow)
content = db.Column(db.Text, nullable=False)
user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)

def __repr__(self):
return f"Post ('{self.title}','{self.date_posted}') "

架构:

class UserSchema(ma.SQLAlchemyAutoSchema):
class Meta:
model = User
sqla_session = db.session

我认为相关的部分控制台错误:

127.0.0.1 - - [14/May/2020 21:33:35] "POST /api/v1/users HTTP/1.1" 500 -
Traceback (most recent call last):
File "/Users/user/.local/share/virtualenvs/apis-JEynsq5i-/Users/user/.pyenv/shims/python/lib/python3.6/site-packages/sqlalchemy/orm/session.py", line 1975, in add
state = attributes.instance_state(instance)
AttributeError: 'dict' object has no attribute '_sa_instance_state'

The above exception was the direct cause of the following exception:
.
.
.
File "/Users/user/.local/share/virtualenvs/apis-JEynsq5i-/Users/user/.pyenv/shims/python/lib/python3.6/site-packages/connexion/decorators/parameter.py", line 121, in wrapper
return function(**kwargs)
File "/Users/user/development/flask/apis/src/users.py", line 100, in create
db.session.add(new_user)
File "/Users/user/.local/share/virtualenvs/apis-JEynsq5i-/Users/user/.pyenv/shims/python/lib/python3.6/site-packages/sqlalchemy/orm/scoping.py", line 162, in do
return getattr(self.registry(), name)(*args, **kwargs)
File "/Users/user/.local/share/virtualenvs/apis-JEynsq5i-/Users/user/.pyenv/shims/python/lib/python3.6/site-packages/sqlalchemy/orm/session.py", line 1978, in add
exc.UnmappedInstanceError(instance), replace_context=err,
File "/Users/user/.local/share/virtualenvs/apis-JEynsq5i-/Users/user/.pyenv/shims/python/lib/python3.6/site-packages/sqlalchemy/util/compat.py", line 178, in raise_
raise exception
sqlalchemy.orm.exc.UnmappedInstanceError: Class 'builtins.dict' is not mapped

我不确定为什么会抛出 Class 'builtins.dict' is not mapped 错误。有什么建议吗?

最佳答案

@IljaEverilä 谢谢,这帮助我解决了问题。

我还在以下位置发现了类似的问题:https://github.com/marshmallow-code/marshmallow/issues/630

建议使用ma​​rshmallow-sqlalchemy

我使用从配置文件创建的 Marshmallow 对象作为:

配置文件:

from flask_marshmallow import Marshmallow
ma = Marshmallow(app)

我的 UserSchema 是:

from .config import db, ma
.
.
.
class UserSchema(ma.SQLAlchemyAutoSchema):
class Meta:
model = User
sqla_session = db.session

并将其更新为:

from marshmallow_sqlalchemy import SQLAlchemyAutoSchema, auto_field

class UserSchema(SQLAlchemyAutoSchema):
class Meta:
model = User
include_relationships = True
load_instance = True

见于:

https://github.com/marshmallow-code/marshmallow-sqlalchemy#generate-marshmallow-schemas

它现在正在工作。

关于python - sqlalchemy.orm.exc.UnmappedInstanceError : Class 'builtins.dict' is not mapped,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/61810855/

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