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创建关联

只要所有元素都是新元素,就可以一步创建带有嵌套关联的实例.

相反,无法执行涉及嵌套对象的更新和删除. 为此,你将必须明确执行每个单独的操作.

BelongsTo / HasMany / HasOne 关联#

考虑以下模型:

class Product extends Model {}
Product.init({
title: Sequelize.STRING
}, { sequelize, modelName: 'product' });
class User extends Model {}
User.init({
firstName: Sequelize.STRING,
lastName: Sequelize.STRING
}, { sequelize, modelName: 'user' });
class Address extends Model {}
Address.init({
type: DataTypes.STRING,
line1: Sequelize.STRING,
line2: Sequelize.STRING,
city: Sequelize.STRING,
state: Sequelize.STRING,
zip: Sequelize.STRING,
}, { sequelize, modelName: 'address' });
// 我们保存关联设置调用的返回值,以便以后使用
Product.User = Product.belongsTo(User);
User.Addresses = User.hasMany(Address);
// 也适用于 `hasOne`

一个新的 Product,User 和一个或多个 Address 可以按以下步骤一步创建:

return Product.create({
title: 'Chair',
user: {
firstName: 'Mick',
lastName: 'Broadstone',
addresses: [{
type: 'home',
line1: '100 Main St.',
city: 'Austin',
state: 'TX',
zip: '78704'
}]
}
}, {
include: [{
association: Product.User,
include: [ User.Addresses ]
}]
});

观察 Product.create 调用中 include 参数的用法. 这对于 Sequelize 理解与关联一起创建的内容很有必要.

注意:这里,我们的用户模型称为user,小写的u-这意味着对象中的属性也应为user. 如果给sequelize.define的名称是User,则对象中的 key 也应该是User. 对于 addresses 也是如此,除了它是 hasMany 关联的复数形式.

一个别名 BelongsTo 关联#

可以扩展前面的示例以支持关联别名.

const Creator = Product.belongsTo(User, { as: 'creator' });
return Product.create({
title: 'Chair',
creator: {
firstName: 'Matt',
lastName: 'Hansen'
}
}, {
include: [ Creator ]
});

HasMany / BelongsToMany 关联#

让我们介绍将产品与许多标签关联的功能. 设置模型如下所示:

class Tag extends Model {}
Tag.init({
name: Sequelize.STRING
}, { sequelize, modelName: 'tag' });
Product.hasMany(Tag);
// 也适用于 `belongsToMany`.

现在,我们可以通过以下方式创建具有多个标签的产品:

Product.create({
id: 1,
title: 'Chair',
tags: [
{ name: 'Alpha'},
{ name: 'Beta'}
]
}, {
include: [ Tag ]
})

并且,我们可以修改此示例以支持别名:

const Categories = Product.hasMany(Tag, { as: 'categories' });
Product.create({
id: 1,
title: 'Chair',
categories: [
{ id: 1, name: 'Alpha' },
{ id: 2, name: 'Beta' }
]
}, {
include: [{
association: Categories,
as: 'categories'
}]
})