[英]sqlalchemy.orm.exc.UnmappedInstanceError: Class 'builtins.NoneType' is not mapped
[英]sqlalchemy.orm.exc.UnmappedInstanceError: Class 'builtins.dict' is not mapped
我正在嘗試使用 SQLAlchemy 和 Marshmallow 將新用戶插入數據庫。 user
參數從 API 端點接收。 一切正常,直到我在create
function 中到達這一行:
db.session.add(new_user)
此時new_user
變量的值是:
{'password': 'string', 'email': 'fave@string', 'username': 'string'}
Function:
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
楷模:
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}') "
架構:
class UserSchema(ma.SQLAlchemyAutoSchema):
class Meta:
model = User
sqla_session = db.session
我認為相關的部分控制台錯誤:
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
我不確定為什么會拋出Class 'builtins.dict' is not mapped
錯誤。 有小費嗎?
@IljaEverilä 謝謝,這幫助我解決了這個問題。
我還在以下位置發現了類似的問題: https://github.com/marshmallow-code/marshmallow/issues/630
建議是使用marshmallow-sqlalchemy 。
我正在使用從配置文件創建的 Marshmallow object:
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
並將其更新為:
from marshmallow_sqlalchemy import SQLAlchemyAutoSchema, auto_field
class UserSchema(SQLAlchemyAutoSchema):
class Meta:
model = User
include_relationships = True
load_instance = True
如圖所示:
https://github.com/marshmallow-code/marshmallow-sqlalchemy#generate-marshmallow-schemas
它現在正在工作。
或者,您可以添加:
load_instance = True
到您的class Meta
,它將為您加載對象。
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