Angular 承诺回调未触发

Question

我有这个应用程序，它使用 $cordovaFileTransfer 将文件上传到服务器，然后将有关该文件的数据发送到同一服务器。文件传输正常。然后将数据发送到服务器，服务器响应。但是响应并没有返回到承诺回调。为什么？

$scope.sendPost = function(data) {

  //first upload a file then send more data about the file
  $cordovaFileTransfer.upload('http://example.com', 'myfile.txt', options)
    .then(function(result) {
      var promise = MyFactory.sendFileData(data);
    });

promise.then(function(response) {
  //we never make it to here
});

}

在 MyFactory 中：

service.sendFileData = function(data) {
  return $http({
    //bunch of parameters. This function works, data is sent to the server and a response received
  }).then(function(response) {
    //this is fired when the response is received from the server. All is good so far.

  return.response.data

  });
}
return service;

Answer 1

$cordovaFileTransfer.upload returns 一个 promise 对象，你可以用它来建立 promise 链机制。

代码

$scope.sendPost = function(data) {

    //get hold on `upload` function promise
    var promise = $cordovaFileTransfer.upload('http://example.com', 'myfile.txt', options)
    .then(function(result)) {
          //return MyFactory.sendFileData promise here which will follow promise chaining
          return MyFactory.sendFileData(data);
        });
    //promise.then will get call once `MyFactory.sendFileData` complete it
    promise.then(function(response) {
        //will get called once `sendFileData` complete its promise
    });
}

Answer 2

这是因为您正在依赖另一个 promise 的 回调来启动 promise 并且..很可能在 promise 被初始化之前您正在附加一个回调 tot .. 所以在您附加回调时，promise 尚未初始化，即 promise 是 null.. 所以在您的控制台中您会看到一个错误。 .

尝试做一些类似

的事情

var x = function(response) {
  //we'll make it to here now...
}
$cordovaFileTransfer.upload('http://example.com', 'myfile.txt', options)
    .then(function(result)) {
      var promise = MyFactory.sendFileData(data);
      promise.then(x);
     });

您应该遵循@PankajParkar 的解决方案，尽管这是更好的方法...

Answer 3

$scope.sendPost = function(data) {

//first upload a file then send more data about the file
$cordovaFileTransfer.upload('http://example.com', 'myfile.txt', options)
.then(function(result)) {
  return MyFactory.sendFileData(result.data);
})
.then(function(response) {

});

Angular 承诺回调未触发

Angular promise callback not firing

promise

angularjs

angularjs-http

ionic-framework

angular-promise