如何与正在履行依赖于其他承诺的承诺的工作？ [英] How to work with promises that rely on other promises being fulfilled?

问题描述

我有一个AngularJS的承诺（用户）依赖于另一个承诺（ userTypes ）正在履行之前，我可以操纵它。从双方的承诺，结果被在控制器中使用，因此，我相信，这意味着我需要从承诺到 $范围变量分配实际的数据：

I have an AngularJS promise (users) that relies on another promise (userTypes) being fulfilled before I can manipulate it. The results from both promises are being used in the controller and as such, I believe that means I need to assign the actual data from the promise to a $scope variable:

// this is all in my controller somewhere
userService.getUserTypes().then(function( data ) {

    $scope.userTypes = data;

}).then(function( data ) {

    userService.getUsers().then(function( data ) {

        $scope.users = data;

        for( var user in $scope.users ) {

            $scope.users[ user ].userType = $filter("filter")( $scope.userTypes, { id: $scope.users[ user ].userTypeID })[0];

        }

    });

});

例如，从结果 userService ：

// userService.getUserTypes()
[
    {
        "id": 1,
        "type": "Administrator"
    },
    {
        "id": 2,
        "type": "User"
    }
]

// userService.getUsers()
[
    {
        "id": 1,
        "name": "Sean Walsh",
        "userTypeID": 2
    },
    {
        "id": 2,
        "name": "Joe Blow",
        "userTypeID": 2
    },
    {
        "id": 3,
        "name": "Joe Administrator",
        "userTypeID": 1
    }
]

这是一个人为的例子（很可能有语法错误），但我相信它可以精确地显示什么，我试图完成：我想确保我的角模型准确地重新$ P $从服务器psents对象图，所以我分配的实际 USERTYPE 对象添加到用户，而不仅仅是重新presenting与类型ID。

That's a contrived example (quite possibly with syntax errors), but I believe it accurately displays what I'm trying to accomplish: I want to make sure that my Angular model accurately represents the object graph from the server, so I am assigning the actual userType objects to the user rather than just representing the type with an ID.

我的这种方法关注的是，我已经可以看到回调地狱的一点点开始嵌套的则（）来电。有没有更好的办法来解决这个问题？

My concern with this approach is that I can already see a little bit of "callback hell" starting with the nested then() calls. Is there a better way to tackle this problem?

推荐答案

从其他承诺架构推断，你可以极有可能返回从诺言然后，然后变成对象中的下。然后适用于

Extrapolating from other promise architectures, you can most likely return a promise from then, which then becomes the object the next .then is applied to.

// this is all in my controller somewhere
userService.getUserTypes().then(function( data ) {

    $scope.userTypes = data;

}).then(function(data) {

    return userService.getUsers();

}).then(function( data ) {

    $scope.users = data;

    for( var user in $scope.users ) {

        $scope.users[ user ].userType = $filter("filter")( $scope.userTypes, { id: $scope.users[ user ].userTypeID })[0];

    }

});;

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