Flask-SQLAlchemy查询多对多 [英] Flask-SQLAlchemy Querying Many-to-Many
问题描述
category_product = db.Table(' category_product',
/ pre>
db.Column('category_id',
db.Integer,
db.ForeignKey('category.id')),
db.Column('product_id' ,
db.teger,
db.ForeignKey('product.id')))
$ b $ class Product(db.Model):
SQLAlchemy Product Model
id = db.Column(db.Integer,primary_key = True)
sku = db.Column(db.String(10),unique = True,nullable = False )
name = db.Column(db.String(80),nullable = False)
categories = db.relationship('Category',secondary = category_product,
backref = db.backref( '类别',
lazy ='dynamic'))
def __init __(self,name):
self.name = name
$ b def __repr __(self):
格式(self.name)
class类别(db.Model):
SQLAlchemy类别模型
id = db.Column(db.Integer,primary_key = True)
name = db.Column(db.String(80),nullable = False)
products = db.relationship(' Product',secondary = category_product,
backref = db.backref('products',lazy ='dynamic'))
def __init __(self,name):
self。 name = name
$ b $ def __repr __(self):
return'< Category {}>'format(self.name)
我试图在给定的
类别中获得所有的
/ code>,由
category_id
指定:
products = db.session.query(Category).\
filter_by(id = category_id).\
products.\
all()
然而,我得到以下异常:
$ p $AttributeError:'Query'对象没有属性'products'
我可能错过了一些简单的东西。
您无法使用属性名称为products的filter_by。首先需要使用all()或first()来捕获结果。另外,既然你使用Flask-SQLAlchemy,我建议不要使用db.session.query(Category),而应该使用Category.query。所以改变这个
products = db.session.query(Category).\
filter_by(id = category_id) 。\
products.\
all()
p>
all_products = Category.query.\
filter_by(id = category_id).\
first() 。\
产品
I have a many-to-many relationship between Categories and Products as follows:
category_product = db.Table('category_product',
db.Column('category_id',
db.Integer,
db.ForeignKey('category.id')),
db.Column('product_id',
db.Integer,
db.ForeignKey('product.id')))
class Product(db.Model):
""" SQLAlchemy Product Model """
id = db.Column(db.Integer, primary_key=True)
sku = db.Column(db.String(10), unique=True, nullable=False)
name = db.Column(db.String(80), nullable=False)
categories = db.relationship('Category', secondary=category_product,
backref=db.backref('categories',
lazy='dynamic'))
def __init__(self, name):
self.name = name
def __repr__(self):
return '<Product {}>'.format(self.name)
class Category(db.Model):
""" SQLAlchemy Category Model """
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(80), nullable=False)
products = db.relationship('Product', secondary=category_product,
backref=db.backref('products', lazy='dynamic'))
def __init__(self, name):
self.name = name
def __repr__(self):
return '<Category {}>'.format(self.name)
I am trying to get all the Product
objects in a given Category
, specified by category_id
:
products = db.session.query(Category).\
filter_by(id=category_id).\
products.\
all()
However, I get the following exception:
AttributeError: 'Query' object has no attribute 'products'
I'm probably missing something simple.
You cannot follow the filter_by with the attribute name 'products'. You first need to catch the results using all() or first(). Also since you are using Flask-SQLAlchemy, I suggest not using db.session.query(Category) and instead Category.query. So change this
products = db.session.query(Category).\
filter_by(id=category_id).\
products.\
all()
to
all_products = Category.query.\
filter_by(id=category_id).\
first().\
products
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