Retrieve JSON information from API using Angular framework

Question

Retrieve JSON information from API using Angular framework

Trying to retrieve JSON data from the address , which is generated using the Flickr API with the following Angular code:

angular.module('myapp', ['ngResource']).
controller('MyController', ['$scope', '$resource', function ($scope,$resource) {
    $scope.photoAPI = $resource("http://www.soe.gr/photos.txt",
{ callback: "JSON_CALLBACK" }, { get: { method: "JSONP" }});
$scope.photos=$scope.photoAPI.get();
}]);

Using $resource to avoid being blocked when retrieving data from another domain, but encountering the error:

Uncaught ReferenceError: jsonFlickrFeed is not defined

.

First question: What kind of typing is this - jsonFlickrFeed({...})?
Second question: How can I access the items property of the JSON object in my $scope for manipulation and continuing with my code as I am currently stuck? Thank you.

javascript angularjs json

Answer 1

Answer №1

When it comes to handling REST APIs, $resource is a common choice. However, while it's technically possible to redefine the get method with jsonp, it's generally more efficient to use $http instead:

  var url = "http://www.soe.gr/photos.txt?callback=JSON_CALLBACK";
  $http.jsonp(url).then(function(response) {
    console.log(response.data);
  });

If you're curious about JSONP, you can read more about it here.

JSONP (JSON with Padding) is a technique used by web developers to overcome cross-domain restrictions and retrieve data from external systems.

The key idea behind JSONP is not to load JSON data directly but rather to load a script that contains a function call with JSON data as a parameter. In AngularJS, this functionality is handled transparently, with Angular providing the necessary callback function name to the requested script. However, if your endpoint is simply a static file and not a script capable of providing a JSONP response with a custom callback function, JSONP won't work.

You can test this concept in action here.

In the provided URL, angular sends the generated callback name as a parameter, which you can see in the network console as:

https://www.flickr.com/services/rest/ ... &jsoncallback=angular.callbacks._0

The response then calls the function using angular.callbacks._0({}).

In conclusion, if your endpoint cannot provide a JSONP response, the main issue lies there.

Answer 2

When it comes to handling REST APIs, $resource is a common choice. However, while it's technically possible to redefine the get method with jsonp, it's generally more efficient to use $http instead:

  var url = "http://www.soe.gr/photos.txt?callback=JSON_CALLBACK";
  $http.jsonp(url).then(function(response) {
    console.log(response.data);
  });

If you're curious about JSONP, you can read more about it here.

JSONP (JSON with Padding) is a technique used by web developers to overcome cross-domain restrictions and retrieve data from external systems.

The key idea behind JSONP is not to load JSON data directly but rather to load a script that contains a function call with JSON data as a parameter. In AngularJS, this functionality is handled transparently, with Angular providing the necessary callback function name to the requested script. However, if your endpoint is simply a static file and not a script capable of providing a JSONP response with a custom callback function, JSONP won't work.

You can test this concept in action here.

In the provided URL, angular sends the generated callback name as a parameter, which you can see in the network console as:

https://www.flickr.com/services/rest/ ... &jsoncallback=angular.callbacks._0

The response then calls the function using angular.callbacks._0({}).

In conclusion, if your endpoint cannot provide a JSONP response, the main issue lies there.

Retrieve JSON information from API using Angular framework

Answer №1

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