How to pass a HTTP response unchanged through an intermediate Web API in ASP.NET Core 3?

Question

In ASP.NET Core 3, what is the best way to call a Web API that I trust from my site (server-side) and pass through its response on my site?

For example, I have a controller action such as this, and I want to just get whatever HTTP status and JSON data, etc. comes out of the call.

[HttpGet]
public async Task<IActionResult> Get(int id){
   string url = "https://...";
   return await httpClient.GetAsync(url);  // not quite right...
}

However, GetAsync returns an HttpResponseMessage. Should I convert this to a IActionResult? If so, how can I do so without resorting to System.Web.Http.ResponseMessageResult from Microsoft.AspNetCore.WebApiCompatShim (since I don't need compatibility with older web API conventions)? I feel like there's a simpler approach I'm missing.

(I'd like the method here with the least overhead, of course, since I'm not seeking to transform or augment the response. No deserialization, especially.)

score 1 · Answer 1 · answered Apr 28 '20 at 19:50

1

The easiest thing you can do is just return the string result. With this aproach you will need to parse the Json string on the client side.

[HttpGet]
public async Task<IActionResult> Get(int id){
   string url = "https://...";
   return await httpClient.GetStringAsync(url);
}

If you want to return a json object you will have to model bind it afaik.

[HttpGet]
public async Task<MyType> Get(int id){
   string url = "https://...";
   var content = await httpClient.GetStringAsync(url);
   // this is Newtonsoft.Json, use the System.Text.Json if you are on .net core 3.*
   return JsonConvert.DeserializeObject<MyType>(content);
}

answered Apr 28 '20 at 19:50

Anton Toshik

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If I call GetStringAsync, I lose the HTTP status, right? – Patrick Szalapski Apr 28 '20 at 19:53
I would love to pass along the status in case of failure. – Patrick Szalapski Apr 28 '20 at 19:54
@PatrickSzalapski Response object that you get from the HttpClient, is not the same as what asp.net core produces as the response. You will need to create custom binding. – Anton Toshik Apr 28 '20 at 19:55
1

@PatrickSzalapski or maybe try something like this? https://stackoverflow.com/questions/42000362/creating-a-proxy-to-another-web-api-with-asp-net-core – Anton Toshik Apr 28 '20 at 19:57
Yes, that AspNetCore.Proxy package is just what I need. Thanks. – Patrick Szalapski Apr 29 '20 at 11:51

score 1 · Answer 2 · answered Apr 29 '20 at 08:09

1

You could try:

[HttpGet]
public async Task<IActionResult> Get()
{
    HttpClient httpClient = new HttpClient();
    string url = "http://localhost:...";
    var response =   httpClient.GetAsync(url).Result;
    var statusCode = response.StatusCode;
    string responseBody = await response.Content.ReadAsStringAsync();
    return Ok(new { StatusCode = statusCode,ResponseBody = responseBody});
}

answered Apr 29 '20 at 08:09

Rena

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Wouldn't that fail to pass along the HTTP status code in case of 4xx or 5xx? – Patrick Szalapski Apr 29 '20 at 11:52

How to pass a HTTP response unchanged through an intermediate Web API in ASP.NET Core 3?

2 Answers2