AngularJS then()的行为与success()不同

参见英文答案 > Why are AngularJS $http success/error methods deprecated? Removed from v1.6?2个
由于在AngularJS中不推荐使用success()和error()函数,我正在更新我的代码,用then()替换它们.现在根据我的理解,这两段代码的行为应该相同：

$http
   .get(/* some params */)
   .success(function() {
      // success cases here
   })
   .error(function() {
      // error cases here
   });

和

$http
   .get(/* some params */)
   .then(function() {
      // success cases here
   },function() {
      // error cases here
   });

但在某些情况下,我会得到不同的行为.你能否向我解释为什么会发生这种情况,更重要的是,使用then()函数保证相同行为的方法是什么？

.success和.error方法忽略返回值.
因此它们不适合链接.

var httpPromise = $http
       .get(/* some params */)
       .success(function onSuccess(data,status,headers,config) {
          var modifiedData = doModify(data);
          //return value ignored
          return modifiedData;
       })
       .error(function onError(data,config) {
          // error cases here
       });

httpPromise.then(function onFullfilled(response) {
    //chained data lost
    //instead there is a response object
    console.log(response.data); //original data
    console.log(response.status); //original status
});

另一方面,.then和.catch方法返回一个派生的promise,适用于从返回(或抛出)值或新promise中链接.

var derivedPromise = $http
       .get(/* some params */)
       .then(function onFulfilled(response) {
          console.log(response.data); //original data
          console.log(response.status); //original status

          var modifiedData = doModify(response.data);
          //return a value for chaining
          return modifiedData;
       })
       .catch(function onRejected(response) {
          // error cases here
       });

derivedPromise.then(function onFullfilled(modifiedData) {
    //data from chaining
    console.log(modifiedData);
});

响应对象与四个参数

另请注意,$http服务在调用提供给.success和.error方法的函数时提供了四个参数(data,config).

$q服务仅为提供给.then或.catch方法的函数提供一个参数(响应).对于由$http服务创建的promises,响应对象具有以下属性：1

> data – {string | Object} – 使用转换函数转换的响应体.
> status – {number} – 响应的HTTP状态代码.
> headers – {function([headerName])} – 标头getter函数.
> config – {Object} – 用于生成请求的配置对象.
> statusText – {string} – 响应的HTTP状态文本.

Chaining promises

Because calling the then method of a promise returns a new derived promise,it is easily possible to create a chain of promises. It is possible to create chains of any length and since a promise can be resolved with another promise (which will defer its resolution further),it is possible to pause/defer resolution of the promises at any point in the chain. This makes it possible to implement powerful APIs.⁰⁷⁰⁰¹

更新

.enccess和.error方法已被弃用并从AngularJS V1.6中删除.

AngularJS then()的行为与success()不同 – error()

Chaining promises

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