Call Web API from MVC Controller using the same HttpClient

Question

I have an MVC5 project, from the MVC controller I need to call the Web API method. The Web API uses token based authentication, so I have to pass the token for each call. I am using the code below to pass the token in the HTTP header:

HttpClient httpClient = new HttpClient();
string baseUrl = "http://localhost:60477/";
dynamic token = Session["token"];
if (token.AccessToken != null)
{
    httpClient.DefaultRequestHeaders.Add("Authorization", String.Format("Bearer {0}", token.AccessToken));
}

There are multiple action methods in my controller, and I want to use a single HttpClient and headers, added in one place, instead of adding a header in each and every action method.

Where can I place the HttpClient headers registration code in the MVC application, so it can be common to all controllers? That means I don't want to repeat code, like adding the token in each and every action method. How can I do that?

Public ActionResult Postuser(UserModel user)
{
    // post code
}

Public ActionResult getuser(UserModel user)
{
    HttpResponseMessage response = httpClient.GetAsync(baseUrl + "api/Admin/GetStates").Result;
    if (response.IsSuccessStatusCode)
    {
        string stateInfo = response.Content.ReadAsStringAsync().Result;
    }

}

Public ActionResult PostRoles(RoleModel role)
{
    // post roles code
}

Dandy · Accepted Answer · 2016-05-12 12:09:46Z

You can try creating a small helper class for creating your httpclient object. Something like

public class HttpClientHelper
{
    public static HttpClient GetHttpClient()
    {
        var MyHttpClient = new HttpClient();
        dynamic _token = HttpContext.Current.Session["token"];
        if (_token == null) throw new ArgumentNullException(nameof(_token));
        MyHttpClient.DefaultRequestHeaders.Add("Authorization", String.Format("Bearer {0}", _token.AccessToken));
        return MyHttpClient;
    }
}

and then call it in your controllers as

public ActionResult getuser(UserModel user)
{
    var httpClient = HttpClientHelper.GetHttpClient();
    HttpResponseMessage response = httpClient.GetAsync(baseUrl + "api/Admin/GetStates").Result;
    if (response.IsSuccessStatusCode)
    {
        string stateInfo = response.Content.ReadAsStringAsync().Result;
    }
}

Ilya Chernomordik · Accepted Answer · 2016-05-12 12:35:25Z

It is better to adhere to the Single Responsibility Principle and extract the interaction with another service in a it's own class, e.g.

public class ServiceClient : IServiceClient
{
    private HttpClient m_Client;        

    public ServiceClient
    {
         m_Client = new HttpClient();
         // Initialize the client as you need here
    }

    public void CallSomeMethod()
    {
        // Call method on the client
    }
}

Then you inject the IServiceClient in your controller and just call it's methods. If you do not use injection (which I advise you do) you can just create a new instance in the controller's constructor.

alphaneer · Accepted Answer · 2016-05-12 18:52:08Z

You can try using an action filter in your controller. Try adding an override that looks something like this-

protected override void OnActionExecuting(ActionExecutingContext filterContext)
{
  // some condition code to target a specific method in the controller
  // Example
  if (filterContext.ActionDescriptor.ActionName == "getuser") // <-- your method
  {
    // put your token based authentication code here
  }

  base.OnActionExecuting(filterContext);
}

The OnActionExecuting method is at the controller scope so you can have different logic for different controllers.

There's also an OnActionExecuted method override if you want to run code after your action method.

------edit--------------

As far as where to place your HttpClient code snippet, you can try this-

protected override void OnActionExecuting(ActionExecutingContext filterContext)
{
  HttpClient httpClient = new HttpClient();
  string baseUrl = "http://localhost:60477/";
  dynamic token = Session["token"];

  if (token.AccessToken != null)
  {
    httpClient.DefaultRequestHeaders.Add(
        "Authorization",
        string.Format("Bearer {0}", token.AccessToken)
    );

    httpClient.BaseAddress = new Uri(baseUrl);
  }

  if(filterContext.ActionParameters.ContainsKey("httpClient"))
  {
    filterContext.ActionParameters["httpClient"] = httpClient;
  }
  else
  {
    // error
  }

  base.OnActionExecuting(filterContext);
}

So the HttpClient object along with the assignment of your baseUrl is established in OnActionExecuting. This code will run before any method returning a ActionResult in the controller you are refactoring. If you want to target some and not all methods, see the first example of OnActionExecuting above.

public ActionResult getuser(UserModel user, HttpClient httpClient)
{
  HttpResponseMessage response = httpClient.GetAsync("api/Admin/GetStates").Result;

  if(response.IsSuccessStatusCode)
  {
    string stateInfo = response.Content.ReadAsStringAsync().Result;
  }

  // the rest of your code for getuser..

  return View();
}

Now your getuser method has an extra parameter ( HttpClient httpClient ).

See the edit's to my post. Also, injecting a service as Ilya Chernomordik suggested is ideal as well as Danny's suggesting to use helper methods. My suggestion may not be the best, but if you want to expore action filter's than give it a try. The HttpClient parameter added to your methods could be refactored into a service object for injection with the code in the OnActionExecuting override method moved into the service object. Hope that helps!

Petar Minev · Accepted Answer · 2016-05-12 06:50:13Z

0

why don't you move the code in Global asax or create custom Atribute?

here is one good link: http://www.diaryofaninja.com/blog/2011/07/24/writing-your-own-custom-aspnet-mvc-authorize-attributes

answered May 12, 2016 at 6:50

Petar Minev

5081 gold badge5 silver badges10 bronze badges

1 Comment

SivaRajini Over a year ago

thanks. how can i place the httpclient code in global.asax file any example ?

Collectives™ on Stack Overflow

Call Web API from MVC Controller using the same HttpClient

4 Answers 4

Comments

Comments

1 Comment

1 Comment

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

1 Comment

1 Comment

Related