我正在使用 Flask-Restless、Flask-SQLAlchemy 和 Marshmallow 开发一个基本的 CRUD JSON REST API。
我在使用这种库组合时遇到了问题，但只有当我使用 Marshmallow 启用反序列化时。
我已经广泛地搜索了这个错误，但是我只在使用数据库关系时发现了类似的问题，而我不是。
我一直在从我的应用程序中删除尽可能多的代码，但仍然遇到相同的错误。以下代码块是本地运行的 1:1。
模型.py：
from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()
class Case(db.Model):
__tablename__ = 'case'
id = db.Column(db.Integer, primary_key=True)
amount = db.Column(db.Integer, nullable=False)
序列化程序.py：
from marshmallow import Schema
class CaseSchema(Schema):
pass # for simplicity - nothing works
case_schema = CaseSchema()
def case_serializer(instance):
return case_schema.dump(instance).data
def case_deserializer(data):
return case_schema.load(data).data
主要.py：
from flask import Flask
import flask_restless
import models
import serializers
app = Flask(__name__)
app.config['DEBUG'] = True
models.db.init_app(app)
def init_db():
with app.app_context():
models.db.create_all()
def init_api():
init_db()
with app.app_context():
api_manager = flask_restless.APIManager(app, flask_sqlalchemy_db=models.db)
api_manager.create_api(models.Case, methods=['GET', 'POST', 'PUT'],
serializer=serializers.case_serializer,
deserializer=serializers.case_deserializer) # <- stuff breaks when enabling this line
if __name__ == "__main__":
init_db()
init_api()
app.run()
测试.py：
import json
import os
import myapp
import unittest
import tempfile
with myapp.app.app_context():
myapp.init_api()
class MyappTestCase(unittest.TestCase):
def setUp(self):
self.db_fd, myapp.app.config['DATABASE'] = tempfile.mkstemp()
myapp.app.config['TESTING'] = True
self.app = myapp.app.test_client()
def tearDown(self):
os.close(self.db_fd)
os.unlink(myapp.app.config['DATABASE'])
def test_create_case(self):
msg = {
"amount": 1038,
}
post_response = self.app.post("/api/case", data=json.dumps(msg),
content_type="application/json")
assert post_response.status_code == 201
if __name__ == '__main__':
unittest.main()
正在使用的版本：
Flask==0.11
Flask-SQLAlchemy==2.1
Flask-Restless==0.17.0
mysqlclient==1.3.7
SQLAlchemy-Utils==0.32.8
marshmallow==2.9.0
最后，运行测试时的完整堆栈跟踪：
======================================================================
ERROR: test_create_case (__main__.myappTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/sqlalchemy/orm/session.py", line 1584, in add
state = attributes.instance_state(instance)
AttributeError: 'dict' object has no attribute '_sa_instance_state'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "myapp_tests.py", line 37, in test_create_case
content_type="application/json")
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/werkzeug/test.py", line 788, in post
return self.open(*args, **kw)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/flask/testing.py", line 113, in open
follow_redirects=follow_redirects)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/werkzeug/test.py", line 751, in open
response = self.run_wsgi_app(environ, buffered=buffered)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/werkzeug/test.py", line 668, in run_wsgi_app
rv = run_wsgi_app(self.application, environ, buffered=buffered)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/werkzeug/test.py", line 871, in run_wsgi_app
app_rv = app(environ, start_response)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/flask/app.py", line 2000, in __call__
return self.wsgi_app(environ, start_response)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/flask/app.py", line 1991, in wsgi_app
response = self.make_response(self.handle_exception(e))
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/flask/app.py", line 1567, in handle_exception
reraise(exc_type, exc_value, tb)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/flask/_compat.py", line 33, in reraise
raise value
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/flask/app.py", line 1988, in wsgi_app
response = self.full_dispatch_request()
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/flask/app.py", line 1641, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/flask/app.py", line 1544, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/flask/_compat.py", line 33, in reraise
raise value
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/flask/app.py", line 1639, in full_dispatch_request
rv = self.dispatch_request()
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/flask/app.py", line 1625, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/flask_restless/views.py", line 157, in decorator
return func(*args, **kw)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/mimerender.py", line 244, in wrapper
result = target(*args, **kwargs)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/flask/views.py", line 84, in view
return self.dispatch_request(*args, **kwargs)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/flask/views.py", line 149, in dispatch_request
return meth(*args, **kwargs)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/flask_restless/views.py", line 189, in wrapped
return func(*args, **kw)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/flask_restless/views.py", line 1449, in post
self.session.add(instance)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/sqlalchemy/orm/scoping.py", line 157, in do
return getattr(self.registry(), name)(*args, **kwargs)
File "/Users/myuser/.virtualenvs/myenv/lib/python3.5/site-packages/sqlalchemy/orm/session.py", line 1586, in add
raise exc.UnmappedInstanceError(instance)
sqlalchemy.orm.exc.UnmappedInstanceError: Class 'builtins.dict' is not mapped