Develop Reference

C# REST API File Upload from Client Code gets 400 Bad Request

I have a Rest API written in .Net core that accepts a File as input as Multipart/Form-data. The API works absolutely fine when I run it from Swagger/Postman.
Here is the API endpoint.
[HttpPost("CreateStudy")]
public ActionResult CreateStudy([FromForm] APIRequest request)
{
// rest of the code
Also here is the APIRequest object. it has only one property which is IFormFile Type.
public class APIRequest
{
public IFormFile XMLFile { get; set; }
}
So far it works well. The problem is that I am trying to write a client side code that will call this API and pass the File from C# code.
But I am always getting a 400-Bad request in the client code.
This is the client code I am trying with.
public string CallServiceWithFileAsync(string EndPointURL, string FilePath)
{
string ResultStatusCode;
Uri uri = new Uri(EndPointURL);
var Client = new HttpClient();
Client.DefaultRequestHeaders.Clear();
//Prepare Message
HttpRequestMessage Message = new HttpRequestMessage();
Message.Method = HttpMethod.Post;
Message.Headers.Add("Accept", "application/octet-stream");
Message.RequestUri = new Uri(EndPointURL);
using (Stream fileStream = File.OpenRead(FilePath))
{
var content = new StreamContent(fileStream);
var response = Client.PostAsync(uri, content);
ResultStatusCode = response.Result.StatusCode.ToString();
}
return ResultStatusCode;
}
What am I doing wrong here? What is the correct way of sending a file into REST endpoint ?

[FromForm] expects an accept header with application/x-www-url-formencoded. If this is not the case, check your output-logs to see why the request is not processed.

Define header for upload file in API

I am trying to upload excel file to convert it to Json, but i need to passing through API Gateway. I have problem to passing the file from API Gateway.
I try to set header in ContentDisposition, ContentLength and ContentType manually.
using (var client = new HttpClient())
{
using (var Content = new MultipartFormDataContent())
{
var name = Path.GetFileName(postedFile.FileName);
HttpContent content = new StringContent("");
content.Headers.Clear();
content.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data")
{
Name = name,
FileName = name
};
content.Headers.Add("Content-Length", postedFile.ContentLength.ToString());
content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("multipart/form-data");
Content.Add(content);
}
HttpResponseMessage reply = new HttpResponseMessage();
reply = await client.GetAsync(#"http://localhost:60897/api/ExceltoJSONConversion");
if (reply.IsSuccessStatusCode)
{
var responseString = await reply.Content.ReadAsStringAsync();
return Json(JsonConvert.DeserializeObject(responseString));
}
}
I have been tried several code but reply always return code 405 MethodNotAllowed.
here my controller where i proceed file
[HttpPost]
[Route("api/ExceltoJSONConversion")]
public IHttpActionResult ExceltoJSONConversion()
{
// Process the file from API Gateway
}
Am i missing something when define Header multipart/form-data? or my code just a mess?

Your API method accepts POST requests only ([HttpPost] attribute).
And in your client you are trying to get API through GET method (client.GetAsync ... ).
Either decorate your API method with [HttpGet] instead of [HttpPost], either change client part to use POST (client.PostAsync ... ).

How to consume a API and return the content in JSON format?

I'm struggling with the following problem:
I've created a solution with the following projects: 1 MVC front-end and 2 test API's for testing my backend API broker.
In my front-end I call my API broker(which is also an API) which sends requests to my 2 test API's. I'm receiving the response of this request in my API Broker in string format and I'm trying to return this into JSON to my front-end, how do I consume this api and return the response in JSON to my front-end? Look code below:
Front-end calling my API Broker:
[HttpGet]
public async Task<ActionResult> getCall()
{
string url = "http://localhost:54857/";
string operation = "getClients";
using (var client = new HttpClient())
{
//get logged in userID
HttpContext context = System.Web.HttpContext.Current;
string sessionID = context.Session["userID"].ToString();
//Create request and add headers
client.BaseAddress = new Uri(url);
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
//Custom header
client.DefaultRequestHeaders.Add("loggedInUser", sessionID);
//Response
HttpResponseMessage response = await client.GetAsync(operation);
if (response.IsSuccessStatusCode)
{
string jsondata = await response.Content.ReadAsStringAsync();
return Content(jsondata, "application/json");
}
return Json(1, JsonRequestBehavior.AllowGet);
}
}
My API Broker consuming one of my two test API's:
[System.Web.Http.AcceptVerbs("GET")]
[System.Web.Http.HttpGet]
[System.Web.Http.Route("RedirectApi")]
public void getCall()
{
setVariables();
WebRequest request = WebRequest.Create(apiUrl);
HttpWebResponse response = null;
response = (HttpWebResponse)request.GetResponse();
using (Stream stream = response.GetResponseStream())
{
StreamReader sr = new StreamReader(stream);
var srResult = sr.ReadToEnd();
sr.Close();
//Return JSON object here!
}
}
I'm also worried that my front-end is expecting a ActionResult instead of a JSON object, I hope you I find some suggestions here.
Thanks in advance!

use HttpClient for making the request which allows you to read the content as string. Your API needs to be configured so it will allow JSON responses (default behavior) and then here is an example of making a request and reading it as string which will be in JSON format (if the API returns a JSON body).
HttpClient client = new HttpClient();
HttpResponseMessage response = await client.GetAsync("http://www.contoso.com/");
response.EnsureSuccessStatusCode();
string responseBody = await response.Content.ReadAsStringAsync();
Receiving JSON data back from HTTP request

C# Web API - POST Request doesn't get executed

I am trying to send a POST request from my ASP.NET Core Web API Project but the request is never sent. The method gets executed with no errors but the request never gets sent out from the async method.
My Implementation:
public async void notify(String message)
{
String url = "MY_WEBSERVICE_URL";
var client = new HttpClient();
client.BaseAddress = new Uri(url);
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, "relativeAddress");
request.Content = new StringContent("application/x-www-form-urlencoded;charset=UTF-8",
Encoding.UTF8, "application/json");
Byte[] byteArray = Encoding.UTF8.GetBytes("{\"text\":\"" + message + "\"}");
request.Content.Headers.ContentLength = byteArray.Length;
await client.SendAsync(request).ContinueWith(responseTask =>
{
Console.WriteLine("Response: {0}", responseTask.Result);
});
}
Is this the proper way of making a POST request from a Core Web API project? Thank you in advance

First of all, there is a dedicated method PostAsync in the HttpClient class ( or even PostAsJsonAsync extension) which you can use to send POST requests without creating HttpRequstMessage manually.
Now about your code - I believe you want to post following JSON string:
{"text":"someMessage"}
You should set this string as a content of StringContent which you are sending:
var json = "{\"text\":\"" + message + "\"}";
request.Content = new StringContent(json, Encoding.UTF8, "application/json");
Currently you are trying to post mediatype string as a value to your API endpoint. Of course it cannot be deserialized into your model.
Note1: StringContent will automatically add Content-Length header with the appropriate value. You should not do that manually.
Note2: Unless this is an event handler, you should not use async void - use async Task instead.
Same task with PostAsJsonAsync usage will look like:
public async Task Notify(string message)
{
var string url = "MY_WEBSERVICE_URL";
var client = new HttpClient();
client.BaseAddress = new Uri(url);
var notification = new Notification { Text = message }; // use some model class
var resonse = await client.PostAsJsonAsync("relativeAddress", notification);
if (response.IsSuccessStatusCode)
{
var content = await response.Content.ReadAsStringAsync();
}
}
In this case, your model will be automatically serialized into JSON, appropriate content will be created and POST request will be sent.

Try Adding [IgnoreAntiforgeryToken] on top of the Post Action like this

WebApi Route fails if streamcontentis not empty

I'm trying to send an object using Web-APi 2 and protobuf-net. I keep getting a 404 error so I assume something goes wrong with the routing?
When I comment out the serialize line
ProtoBuf.Serializer.Serialize(memstream, package);
(so the memory stream stays empty) the routing works and RecievePackage is called. And the package parameter is empty. (the package object itsself is not NULL but all it's properties are.)
Whenever the memory stream is not empty I get a 404 error. What am I doing wrong here?
Receive code:
[Route("Receive")]
[HttpPost]
public async Task<IHttpActionResult> RecievePackage(PackageModel package)
{
id = await SavePackage(package);
return Created("", id);
}
Send code:
private async Task SyncUpAsync(string apiUrl, PackageModel package)
{
using (HttpClient client = new HttpClient())
using (var memstream = new MemoryStream())
{
var uri = new Uri(new Uri(ApiUrl), apiUrl);
ProtoBuf.Serializer.Serialize(memstream, package);
memstream.Position = 0;
var content = new StreamContent(memstream);
content.Headers.Add("SyncApiToken", ApiKey);
content.Headers.Add("Content-Type", "application/x-protobuf");
var response = await client.PostAsync(uri, content);
}
}