角服务承诺 [英] Angular Service Promises

问题描述

所以，我有一个角度的应用程序，向服务器宁静的电话。有一个封装到服务器的调用的服务。我现在有上简单地返回从$ http服务承诺服务的方法。我想加到这个方法调用一些额外的处理，但我不知道该怎么做，因为承诺的异步特性。

So, I've got an Angular app that makes restful calls to the server. There is a service that wraps up the calls to the server. I currently have a method on the service that simply returns the promise from the $http service. I'd like to add some additional processing on that method call, but I'm not sure how to do it because of the asynchronous nature of the promise.

目前在打字稿：

class BoardService {
    private $http;

    constructor($rootScope: IRootScope, $http: ng.IHttpService) {
          this.$http = $http;
    }

    fetchBoard(id: number) {
        return this.$http.get("/api/board/" + id);
    }
}

我希望得到它是这样的：

I'd like to get it to something like this:

fetchBoard2(id: number) {
    this.$http.get("/api/board/" + id).success(function(data)
    {
        // Manipulate the data

    });

    // return manipulated data; 
}

你会怎么做呢？

推荐答案

整蛊一句警告！由于承诺是异步的，任何基于从承诺本身必须返回一个承诺数据返回的数据。你想 fetchBoard2 来返回被曾经的 $ HTTP 承诺解决的承诺已经回来了，你已经操纵数据。为此，您可以角的 $ Q 服务。

Tricky sentence warning! Because promises are asynchronous, anything returning data based on data from a promise must itself return a promise. You want fetchBoard2 to return a promise that gets resolved once the $http promise has come back and you've manipulated the data. You do this with Angular's $q service.

fetchBoard2(id: number) {
  var deferred = $q.defer();

  $http.get("/api/board/" + id).success(function(data) {
    var newData = doSomething(data);
    deferred.resolve(newData);
  });

  return deferred.promise;
}

额外的管理对象递延迅速得到繁琐，所以你可以使用然后来插入自己的操作进入管道。

Managing extra deferred objects gets quickly fiddly, so you can use then to insert your own manipulation into the pipeline.

fetchBoard3(id: number) {
  return $http.get(...).then(function(data) {
    return doSomething(data);
  });
}

有关更多详细信息，这里的<一个href=\"http://chariotsolutions.com/blog/post/angularjs-corner-using-promises-q-handle-asynchronous-calls/\">a好文章。

For more detail, here's a good article.

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