创建一个属于其他两个对象的对象

Question

我正在使用 sequelize.js V.5 创建一个简单的 api，用于发布书籍的 cmets。评论应该通过图书 id 属于图书，并且对于发布的用户来说也是一样的。

我不太确定如何创建它。

//user model
...
User.hasMany(models.Comment)
...

//book model
...
Book.hasMany(models.Comment);
...

//comment model
...
Comment.belongsTo(models.User);
Comment.belongsTo(models.Book);
...
//route
...
Comment.create(
    {
        //what do i put here? or what other syntax i use
     }
)

Answer 1

根据文档需要关联对象

直接来自文档的标准示例

关联对象

Because Sequelize is doing a lot of magic, you have to call Sequelize.sync after setting the associations! Doing so will allow you the following:

Project.belongsToMany(Task)
Task.belongsToMany(Project)

Project.create()...
Task.create()...
Task.create()...

// save them... and then:
project.setTasks([task1, task2]).then(function() {
  // saved!
})

// ok, now they are saved... how do I get them later on?
project.getTasks().then(function(associatedTasks) {
  // associatedTasks is an array of tasks
})

// You can also pass filters to the getter method.
// They are equal to the options you can pass to a usual finder method.
project.getTasks({ where: 'id > 10' }).then(function(tasks) {
  // tasks with an id greater than 10 :)
})

// You can also only retrieve certain fields of a associated object.
project.getTasks({attributes: ['title']}).then(function(tasks) {
    // retrieve tasks with the attributes "title" and "id"
})

要删除已创建的关联，您只需调用不带特定 id 的 set 方法：

// remove the association with task1
project.setTasks([task2]).then(function(associatedTasks) {
  // you will get task2 only
})

// remove 'em all
project.setTasks([]).then(function(associatedTasks) {
  // you will get an empty array
})

// or remove 'em more directly
project.removeTask(task1).then(function() {
  // it's gone
})

// and add 'em again
project.addTask(task1).then(function() {
  // it's back again
})

至于你的问题：

一定是这样的：

Comment.create(
    {
        // create new comment as you like
     }

然后类似（根据需要）

comment.setUser(user).then(function() {
  // saved!
})

comment.setBook(book).then(function() {
  // saved!
})