AngularJS：返回承诺的响应-即上传图片然后提交表格

Question

I'm trying to understand promises and $q in AngularJS. I'd like to chain 2 functions, and execute them in order. The first is a file upload, and can take a while, so I need to wait for it to be executed before creating a DB record for it. I was originally using angular 1.3, hence the .success and .error methods.

Here's the code:

    //image upload function 

    $scope.imageUpload = function(){
        return $q(function (resolve, reject) {
              var fd = new FormData();
              fd.append("file", $scope.imageFile);
              var data = fd;
              var url = 'http://myApiUrl';
              var postObject = {
                  method: 'POST',
                  url: url,
                  data: data
              }
              $http(postObject)
                 .success(function(response) {
                     return response; 
              }).error(function(response) {
                     return response; 
              });
          })
      }

    // create a DB record 
    $scope.recordCreate = function(previousResponse){
          return $q(function (resolve, reject) {

               // does stuff with previousResponse, and creates a db record

            })
        };

    // do functions in order 

    $scope.imageUpload().then(
            $scope.recordCreate(response)
          );

Not only am I getting the error

ReferenceError: response is not defined

(in relation to that last line, $scope.recordCreate(response)), but also the second function is executing BEFORE the first!

I have tried to follow the docs here https://docs.angularjs.org/api/ng/service/ $q but in my example I can't get my first function to return a response to the 2nd. Does anyone know why?

Answer 1

You should use .then() instead of .success() to return your promise which you can then act upon and call the subsequent method.

Also, I'm curious as to why you wouldn't just update the DB server-side on your file-upload call.

Answer 2

no need to use $q to execute http requests in order. use promise chains to call the request after another

$scope.imageUpload = function() {
    var fd = new FormData();
    fd.append("file", $scope.imageFile);
    var data = fd;
    var url = 'http://myApiUrl';
    var postObject = {
        method: 'POST',
        url: url,
        data: data
    }
    return $http(postObject)
}
$scope.recordCreate = function(previousResponse) {
    var url = 'db_url';
    var postObject = {
        method: 'POST',
        url: url,
        data: previousResponse
    }
    return $http(postObject)
};
$scope.imageUpload()
    .then(function(response) {
        return $scope.recordCreate(response.data)
    })
    .then(function(response) {
        console.log(response.data);
    })