Sequelize 中的 Promise:如何从每个 Promise 中获取结果 [英] Promises in Sequelize: how to get results from each promise

问题描述

在 Sequelize >=1.7 我们可以使用承诺

In Sequelize >=1.7 we can use promises

你能解释一下我如何在这段代码中从每个用户那里获取值吗:

Can you explain for me how can i get values from each user in this code:

var User = sequelize.define("user", {
  username: Sequelize.STRING
})


User
  .sync({ force: true })
  .then(function() { return User.create({ username: 'John' }) })
  .then(function(john) { return User.create({ username: 'Jane' }) })
  .then(function(jane) { return User.create({ username: 'Pete' }) })
  .then(function(pete) {
    console.log("we just created 3 users :)")
    console.log("this is pete:")
    console.log(pete.values)

    // what i want:
    console.log("this is jane:")
    console.log(jane.values)

    console.log("this is john:")
    console.log(john.values)
  })

UPD

所有值都需要设置与其他模型的关联.其实我需要一些这样的代码:

All values need for set associations with other Model. Actually i need some like this code:

User.hasMany(Group)
Group.hasMany(User)

User
  .sync({ force: true })
  .then(function() { return User.create({ username: 'John' }) })
  .then(function(john) { return User.create({ username: 'Jane' }) })
  .then(function(jane) { return User.create({ username: 'Pete' }) })
  .then(function(pete) { return Group.findOrCreate({id: 1}) })
  .then(function(group) {return group.setUsers([john, jane, pete])})
  .then(function(result) { console.log(result)})
})

推荐答案

Bluebird 方式是 收集帮助函数.

The Bluebird way are the collection helper functions.

如果您想并行创建它们，请使用 map:

If you want to create them in parallel, use map:

User.sync({ force: true })
  .then(function() {
    return Promise.map( ['John', 'Jane', 'Pete'], function(name) {
      return User.create({ username: name });
    })
  }).spread(function(john, jane, pete) {
    console.log("we just created 3 users :)")
    console.log("this is john:")
    console.log(john.values)
    console.log("this is jane:")
    console.log(jane.values)
    console.log("this is pete:")
    console.log(pete.values)
  })

如果您需要连续创建它们，只需将其更改为 mapSeries (3.0+).

If you need to create them consecutively, just change it to mapSeries (3.0+).

如果数组不需要是动态的，并且您只想像示例中那样通过承诺链传递共享值，请查看 如何在 .then() 链中访问之前的承诺结果?.

If the array doesn't need to be dynamic, and you simply want to pass a shared value through the promise chain like in your example, have a look at How do I access previous promise results in a .then() chain?.

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