Flask之 Marshmallow 踩坑实录

1.Marshmallow.ModelSchema 报错

  AttributeError: 'Marshmallow' object has no attribute 'ModelSchema'

`from flask_sqlalchemy import SQLAlchemy
from flask_marshmallow import Marshmallow
app = Flask(name)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///marshmallowjson.db'

db = SQLAlchemy(app)
ma = Marshmallow(app)
class User(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(50))

class Item(db.Model):
id = db.Column(db.Integer, primary_key=True)
item_name = db.Column(db.String(50))
user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
user = db.relationship('User', backref='items')

class UserSchema(ma.ModelSchema):
class Meta:
model = User

class ItemSchema(ma.ModelSchema):
class Meta:
model = Item
@app.route('/')
def index():
users = User.query.all()
user_schema = UserSchema(many=True)
output = user_schema.dump(users).data
return jsonify({'user': output})

if name == 'main':
app.run(debug=True)
`

解决： pip install marshmallow-sqlalchemy

原因： 仅安装了烧瓶棉花糖，整个代码保持不变，但需要添加以使用SQLAlchemy。

问题二： flask_marshmallo>=0.12.0,ma.ModelSchema和ma.TableSchema被删除

  from flask import Flask

from flask_sqlalchemy import SQLAlchemy
from flask_marshmallow import Marshmallow

app = Flask(name)
app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:////tmp/test.db"

db = SQLAlchemy(app)
ma = Marshmallow(app)

flask-marshmallow<0.12.0

class AuthorSchema(ma.ModelSchema):
class Meta:
model = Author

flask-marshmallow>=0.12.0 (recommended)

class AuthorSchema(ma.SQLAlchemyAutoSchema):
class Meta:
model = Author
load_instance = True

flask-marshmallow>=0.12.0 (not recommended)

from marshmallow_sqlalchemy import ModelSchema

class AuthorSchema(ModelSchema):
class Meta:
model = Author
sql_session = db.session