Parse JSON from C# to AngularJS

Question

I have an array of file names:

[HttpPost]
    public JsonResult GetJSONFilesList()
    {
        string[] filesArray = Directory.GetFiles("/UploadedFiles/");
        for (int i = 0; i < filesArray.Length; i++)
        {
            filesArray[i] = Path.GetFileName(filesArray[i]);
        }

        return Json(filesArray);
    }

I need this in AngularJS as a list of objects so I can ng-repeat it out and apply filters. I'm unable to figure out how to get the JSON from the MVC controller to AngularJS.

I've tried the following to make it visible to the view for angular to grab, but I don't know how to make the ng-init see the function to return the list. It erros on "SerializeObject(GetJSONFilesList())" saying it doesn't exist in current context.

<div ng-controller="MyController" data-ng-init="init(@Newtonsoft.Json.JsonConvert.SerializeObject(GetJSONFilesList()),
         @Newtonsoft.Json.JsonConvert.SerializeObject(Model.Done))" ng-cloak>
        </div>

EDIT: I've tried using http.get.

Test one:

alert('page load'); 
$scope.hello = 'hello';   

$http.get('http://rest-service.guides.spring.io/greeting').
        then(function (response) {
            $scope.greeting = response.data;
            alert($scope.greeting);
        });

 alert($scope.hello);

The alert in the http.get never fires, the other alerts do however.

Test two:

$http({
        url: '/Home/testHello',
        method: 'GET'
    }).success(function (data, status, headers, config) {
        $scope.hello = data;
        alert('hi');
        });




[HttpPost]
        public string testHello()
        {
            return "hello world"; 
        }

This causes the angular to break and nothing in the .js works.

Test three

    alert('page load'); 
    $scope.hello = 'hello';  
    $scope.GetJSONFilesList = function () {
        $http.get('/Home/testHello')
            .success(function (result) {
                $scope.availableFiles = result;

                alert('success');
            })
            .error(function (data) {
                console.log(data);
                alert('error');
            });
        alert('hi');
    };
alert($scope.hello);

[HttpPost]
            public string testHello()
            {
                return "hello world"; 
            }

Alerts nothing from within it, other alerts work.

Fixed:

After some googling, I've found that using .success and .error are deprecated and that .then should be used. So by using .then this resulted in the C# being hit via debug.

Then after using console.log on the returned value found that to have anything be returned I needed to return the value from C# using "return Json(myValue, JsonRequestBehavior.AllowGet); "

And by viewing the object in the console in Chrome by using console.log, I could see my values were in the data part of the returned object.

It was stored in data as an array (as I was passing an array).

I could then get the data out of there by assigning the returned value.data to a scope and could call that in the view {{result[1]}} etc.

return Json(filesArray, JsonRequestBehavior.AllowGet);

$scope.fileList;
    $http.get("/Home/GetFileList").then(function (result) {
        console.log(result)
        $scope.fileList = result.data;
    })

Answer 1

other answers say to use .success in the angular function, .success and .error are deprecated, instead .then should be used.

Working result:

MVC:

public JsonResult GetFileList()
    {
        //form array here
        return Json(myArray, JsonRequestBehavior.AllowGet);
    }

The function needs to be of type JsonResult, and the returned value of Json using JsonRequestBehavior.AllowGet.

AngularJS:

$scope.fileList;
    $http.get("/Home/GetFileList").then(function (result) {
        console.log(result)
        $scope.fileList = result.data;
    })

This is in my AJS controller, using .then instead of .success. If you use console.log the result returned from the mvc controller and view it in the browser inspect you'll see the object with lots of other info and the values you want are in the .data section of the object.

So to access the values you need to do result.data. In my case this gives me and array. I assign this to a scope. Then in my view I can access the values by doing {{fileList[1]}} etc. This can also be used in ng-repeat e.g:

<div ng-repeat="file in fileList">                        
                    {{fileList[$index]}}
</div>

Each value in the array in the repeat can be accessed using $index which is the number of the repeat starting at 0.

Answer 2

Imagine that you divide your front end in three layers (MVC or MVVM) whatever you want.

When you need info from server, the best practice is to separate the logic that makes the request and the logic that manipulates the data.

More info about how to make the request you can find it reading about REST APIS in Consuming a RESTful Web Service with AngularJS.

Normally one of the layers requires the use of services and you can have your controllers and your services (the place where you get the raw data from the server and you make the request. For that you need to use the $http service from angularjs.

$http: The $http service is a core AngularJS service that facilitates communication with the remote HTTP servers via the browser's XMLHttpRequest object or via JSONP.

So basically it shows you how to make get, post and put requests. One example from the documentation is :

// Simple GET request example:
 $http({
  method: 'GET',
 url: '/someUrl'
}).then(function successCallback(response) {
    // this callback will be called asynchronously
    // when the response is available
  }, function errorCallback(response) {
    // called asynchronously if an error occurs
    // or server returns response with an error status.
  });

Pay attention to the url because there is the place where you let your request knwow which method is going to be hit on the server to take the action. If your request is succesful, then you can use the parameter called response. From there, you can do whatever you want. If you decide to make that request part from your controller, you can assign it directly to a variable on your scope. Pay attention if you need to serialize the data. Something like

$scope.myResponseName = response.name ; 

The first documentation link from above shows this example which does exactly what I tell you.

angular.module('demo', [])
.controller('Hello', function($scope, $http) {
   $http.get('http://rest-service.guides.spring.io/greeting').
       then(function(response) {
        $scope.greeting = response.data;
       });
  });

After all the mentioned above, pay attention to what you want to display. Are you going to display the elements of an object array? The use on your HTML the ng-repeat directive. Are you going to display just a variable (No array nor object) then you use need to use an angular expression {{ }}

In summary:

1. By making an HTTP request, hit the correct method on server.
2. Make sure you are sending the JSON correctly and that the data is correct.
3. Retrieve the data on your response.
4. Assign the data to a variable on your scope and serialize the data if needed.
5. Display the data correctly depending if it is within an array, if it´s an object or if its just a variable.

I hope the explanation makes sense and check the documentation if you need more info.

Answer 3

You can build your viewmodel so that it contains the data you'd like to serialize and then pass it to angularJS in your view as follows:

<div ng-controller="MyController" data-ng-init="init(@JsonConvert.SerializeObject(myArrayData),
     @Newtonsoft.Json.JsonConvert.SerializeObject(Model.Done))" ng-cloak>

and then in your angular controller have a function to receive the data as follows:

$scope.init = function (myArrayData) {
    //do something with data
  };

The above assumes you're trying to pass data from mvc to angularjs on page load. If you're trying to hit a controller and get data back to angularjs upon some event such as a button click, then you can write an angularjs function similar to the following (this will be an asynchronous request):

app.controller('MyController', function ($scope, $http, $window) {

        $scope.ButtonClick = function () {
            var post = $http({
            method: "POST",
            url: "/SomeController/SomeAjaxMethod",
            dataType: 'json',
            data: { path: $scope.Path},
            headers: { "Content-Type": "application/json" }
        });

        post.success(function (data, status) {
            //do something with your data
        });

        post.error(function (data, status) {
            $window.alert(data.Message);
        });
    }
}

and your controller action would look something like:

[HttpPost]
public JsonResult SomeAjaxMethod(string path)
{
    string[] filesArray = Directory.GetFiles(path);

    for (int i = 0; i < filesArray.Length; i++)
    {
        filesArray[i] = Path.GetFileName(filesArray[i]);
    }

    return Json(filesArray);
}