jstacks jstacks - 4 months ago 8
JSON Question

AngularJS: factory $http.get JSON file

I am looking to develop locally with just a hardcoded JSON file. My JSON file is as follows (valid when put into JSON validator):

{
"contentItem": [
{
"contentID" : "1",
"contentVideo" : "file.mov",
"contentThumbnail" : "url.jpg",
"contentRating" : "5",
"contentTitle" : "Guitar Lessons",
"username" : "Username",
"realname" : "Real name",
"contentTags" : [
{ "tag" : "Guitar"},
{ "tag" : "Intermediate"},
{ "tag" : "Chords"}
],
"contentAbout" : "Learn how to play guitar!",
"contentTime" : [
{ "" : "", "" : "", "" : "", "" : ""},
{ "" : "", "" : "", "" : "", "" : ""}
],
"series" :[
{ "seriesVideo" : "file.mov", "seriesThumbnail" : "url.jpg", "seriesTime" : "time", "seriesNumber" : "1", "seriesTitle" : "How to Play Guitar" },
{ "videoFile" : "file.mov", "seriesThumbnail" : "url.jpg", "seriesTime" : "time", "seriesNumber" : "2", "seriesTitle" : "How to Play Guitar" }
]
},{
"contentID" : "2",
"contentVideo" : "file.mov",
"contentThumbnail" : "url.jpg",
"contentRating" : "5",
"contentTitle" : "Guitar Lessons",
"username" : "Username",
"realname" : "Real name",
"contentTags" : [
{ "tag" : "Guitar"},
{ "tag" : "Intermediate"},
{ "tag" : "Chords"}
],
"contentAbout" : "Learn how to play guitar!",
"contentTime" : [
{ "" : "", "" : "", "" : "", "" : ""},
{ "" : "", "" : "", "" : "", "" : ""}
],
"series" :[
{ "seriesVideo" : "file.mov", "seriesThumbnail" : "url.jpg", "seriesTime" : "time", "seriesNumber" : "1", "seriesTitle" : "How to Play Guitar" },
{ "videoFile" : "file.mov", "seriesThumbnail" : "url.jpg", "seriesTime" : "time", "seriesNumber" : "2", "seriesTitle" : "How to Play Guitar" }
]
}
]
}


I've gotten my controller, factory, and html working when the JSON was hardcoded inside the factory. However, now that I've replaced the JSON with the $http.get code, it doesn't work. I've seen so many different examples of both $http and $resource but not sure where to go. I'm looking for the simplest solution. I'm just trying to pull data for ng-repeat and similar directives.

Factory:

theApp.factory('mainInfoFactory', function($http) {
var mainInfo = $http.get('content.json').success(function(response) {
return response.data;
});
var factory = {}; // define factory object
factory.getMainInfo = function() { // define method on factory object
return mainInfo; // returning data that was pulled in $http call
};
return factory; // returning factory to make it ready to be pulled by the controller
});


Any and all help is appreciated. Thanks!

Answer

Okay, here's a list of things to look into:

1) If you're not running a webserver of any kind and just testing with file://index.html, then you're probably running into same-origin policy issues. See:

http://code.google.com/p/browsersec/wiki/Part2#Same-origin_policy

Many browsers don't allow locally hosted files to access other locally hosted files. Firefox does allow it, but only if the file you're loading is contained in the same folder as the html file (or a subfolder).

2) The success function returned from $http.get() already splits up the result object for you:

$http({method: 'GET', url: '/someUrl'}).success(function(data, status, headers, config) {

So it's redundant to call success with function(response) and return response.data.

3) The success function does not return the result of the function you pass it, so this does not do what you think it does:

var mainInfo = $http.get('content.json').success(function(response) {
        return response.data;
    });

This is closer to what you intended:

var mainInfo = null;
$http.get('content.json').success(function(data) {
    mainInfo = data;
});

4) But what you really want to do is return a reference to an object with a property that will be populated when the data loads, so something like this:

theApp.factory('mainInfo', function($http) { 

    var obj = {content:null};

    $http.get('content.json').success(function(data) {
        // you can do some processing here
        obj.content = data;
    });    

    return obj;    
});

mainInfo.content will start off null, and when the data loads, it will point at it.

Alternatively you can return the actual promise the $http.get returns and use that:

theApp.factory('mainInfo', function($http) { 
    return $http.get('content.json');
});

And then you can use the value asynchronously in calculations in a controller:

$scope.foo = "Hello World";
mainInfo.success(function(data) { 
    $scope.foo = "Hello "+data.contentItem[0].username;
});
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