ASP.NET MVC Core - Consume API through HttpClient

Question

I have a Visual Studio solution with two projects; API and MVC. MVC is my MVC-project containing my views etc., API is my API-project containing the API-endpoints and logic. Since I have two projects, I have configured my solution to have multiple startup-projects.

HttpClient

public const string AuctionAPI = "http://localhost:44337/";
public const string AuctionClient = "http://localhost:44398/";

public static HttpClient GetClient()
{
    HttpClient client = new HttpClient();
    client.BaseAddress = new Uri(AuctionAPI);
    client.DefaultRequestHeaders.Accept.Clear();
    client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));
    return client;
}

MVC Controller (Notice: I receive the error on line 6, when I set HttpResponseMessage and try to call client.GetAsync()

[Route("item/{itemNumber}")]
public async Task<IActionResult> IndexForItem(int itemNumber)
{
    var client = GetClient();
    //ERROR: In next line, HttpResponseMessage it tries to call my API controller and fails
    HttpResponseMessage response = await client.GetAsync($@"api/Auction/SeeOneItem/{itemNumber}");

    if (response.IsSuccessStatusCode)
    {
        string content = await response.Content.ReadAsStringAsync();
        var model = await response.Content.ReadAsAsync<AuctionItemProxy>();

        return View(model);
    }
    else
    {
        return Content("An error occured.");
    }
}

API Controller (Notice: my breakpoint in this method never hits)

[HttpGet("SeeOneItem/{itemNumber:int}")]
public AuctionItem GetAuctionItem(int itemNumber)
{
    var item = _auctionItemDataFactory.AuctionItems.First(x => x.ItemNumber == itemNumber);
    if (item == null)
    {
        return null;
    }
    return _auctionItemDataFactory.AuctionItems.First(x => x.ItemNumber == itemNumber);
}

Actual error I receive

IOException: Unable to read data from the transport connection

Both projects in the same solution using IIS Express? Are you sure the first (API) is actually running when you are running the second (MVC)? — sellotape, Dec 07 '18 at 09:32
check this https://stackoverflow.com/questions/5420656/unable-to-read-data-from-the-transport-connection-an-existing-connection-was-f — Hitesh Anshani, Dec 07 '18 at 09:36
This problem also occurs if circular reference exists inside table definition. Try disabling lazy loading and proxy creation (assumed using EF Core). — Tetsuya Yamamoto, Dec 07 '18 at 09:40
@sellotape Yes, the problem has been correctly identified in the answer. Thanks for trying to help — thesystem, Dec 08 '18 at 10:26
@D-johnAnshani Thanks for the link, the problem was identified in the answer below — thesystem, Dec 08 '18 at 10:26
@TetsuyaYamamoto Thanks for the pointer, the problem was identified in the answer below — thesystem, Dec 08 '18 at 10:26

score 1 · Accepted Answer · answered Dec 07 '18 at 10:55

This error means that the target machine is accessible but the service you are trying to reach is not accessible.

By looking at your code you shared I noticed one thing. If the project is set up to use Https then IIS Express assigns ports starting with 443 resulting in a port like 443xx. Change your http scheme to https and try again.

public const string AuctionAPI = "http://localhost:44337/";

to

public const string AuctionAPI = "https://localhost:44337/";

OR

Change your project settings to not use SSL

Right Click your project Go to properties
In properties window go to Debug section
Under Web Server Settings un-check "Enable SSL"

This issue can also be related to transport level security.

ASP.NET MVC Core - Consume API through HttpClient

1 Answers1