How can I extend $q promise in Angularjs with a .s

问题:

I wrote this little code in a custom service in AngularJS.

In my service:

        var deferred = $q.defer();
        var promise = deferred.promise;

        deferred.resolve('success');
        deferred.reject('error');

        /* Handle success and error */
        promise.success = function(fn) {

            promise.then(function(response) {

                fn(response);

            });

            return promise;
        };

        promise.error = function(fn) {

            promise.then(null, function(response) {

                fn(response);

            });

            return promise;
        };

In my controller:

        promiseService.myPromise()
            .success(function(data){

                $scope.success= data;

            })
            .error(function(data){

                $scope.error = data;

            });

I juste Handle the Success and Error from the promise ($q service). I need this code in a lot of other service so I would to extend directly the $q service with a custom.

So I would like something like this in my service:

    var deferred = myPromiseService.$qCustom.defer();
    var promise = deferred.promise;

    deferred.resolve('success');
    deferred.reject('error');

    return promise;

Any idea? I found some explanation to extend filter in Angularjs my problem is to find the good way to extend all the functionality of the $q and add my custom.

I start with something like that, it's work to handle the $q out of the box :

angular.module('myApp').service('myPromiseService', function($q){

  $qCustom = $q;  

});

回答1:

Here's a full solution picking up where @jessegavin left off.

var myApp = angular.module("myApp", []);

myApp.config(function ($provide) {

  $provide.decorator('$q', function ($delegate) {
    var defer = $delegate.defer;
    $delegate.defer = function () {
      var deferred = defer();
      deferred.promise.success = function (fn) {
        deferred.promise.then(function(response) {
          fn(response.data, response.status, response.headers);
        });
      return deferred.promise;
      };
      deferred.promise.error = function (fn) {
        deferred.promise.then(null, function(response) {
          fn(response.data, response.status, response.headers);
        });
        return deferred.promise;
      };
      return deferred;
    };
    return $delegate;
  });

});

回答2:

If you want to change the default behavior of something that is injected by angular, you can use the decorator() method on the $provide service.

var myApp = angular.module("myApp", []);

myApp.config(function ($provide) {
  $provide.decorator("$q", function($delegate) {
    // The $delegate argument here refers to the $q service.

    $delegate.defer = function() {
      alert("You just tried to call defer()!");
    };

    // Now, every time angular provides an instance of $q via
    // injection, it will return your customized version of $q.

    return $delegate;
  });
});

See the example above in action at http://plnkr.co/edit/RuZF2cGkVHwlu7NIhxEZ?p=preview

As to modifying $q to add the success and error functions, I am not sure at the moment. But I am pretty sure that this is where you'd want to do it.

回答3:

IMHO, @jessegavin 's decoration of $q is not perfect, it shouldn't return origin promise in success&error function. It will lose feature of flatten the callback pyramid.

And it can't split response data to success&error function $httpPromise dose.

for example

//can't do this..
somePromise.success(function(){
  return $http.get(...)//another primise
}).success(function(data){
  //data from $http.get..
})

Here is my version, it will recognize http response and will return the next promise. Make your own $q have the same behavior like $httpPromise

$provide.decorator('$q', function($delegate) {
  function httpResponseWrapper(fn) {
    return function(res) {
      if (res.hasOwnProperty('data') && res.hasOwnProperty('status') && res.hasOwnProperty('headers') && res.hasOwnProperty('config') && res.hasOwnProperty('statusText')) {
        return fn(res.data, res.status, res.headers, res.config, res.statusText);
      } else {
        return fn(res);
      }
    };
  };
  function decorator(promise) {
    promise.success = function(fn) {
      return decorator(promise.then(httpResponseWrapper(fn)));
    };
    promise.error = function(fn) {
      return decorator(promise.then(null, httpResponseWrapper(fn)));
    };
    return promise;
  };
  var defer = $delegate.defer;
  $delegate.defer = function() {
    var deferred = defer();
    decorator(deferred.promise);
    return deferred;
  };
  return $delegate;
});