We Keep Coding

C# .NET Core 3.1 Web API Post parameter is Null

I am trying to make a post request from WPF to Web API using the following code but the request parameter is always null.
Request Model
public class Document
{
public string FileName { get; set; }
public byte[] Buffer { get; set; }
}
public class Request
{
public string Uploader { get; set; }
public List<Document> Documents { get; set; }
}
WPF Client
var obj = new Request()
{
Uploader = "John Doe",
Documents = new List<Document>
{
new Document()
{
FileName ="I Love Coding.pdf",
Buffer = System.IO.File.ReadAllBytes(#"C:\Users\john.doe\Downloads\I Love Coding.pdf.pdf")
}
}
};
using (var http = new HttpClient())
{
var encodedJson = JsonConvert.SerializeObject(obj);
var conent = new StringContent(encodedJson, Encoding.UTF8, "application/json");
HttpResponseMessage response = await http.PostAsync("https://my-app.com/api/upload", conent);
response.EnsureSuccessStatusCode();
}
Web API
[Route("")]
public class AppController : ControllerBase
{
[HttpPost]
[Route("api/upload")]
public async Task<IActionResult> UploadDocumentsAsync([FromBody] Request request)
{
// request is always null when app is running in production
// https://my-app.com/api/upload
//request is not null when running on https://localhost:8080/api/upload
}
}
Please what am I missing in the above implementation?
The request parameter is not null on localhost but always null in production.

Please what am I missing in the above implementation? The request
parameter is not null on localhost but always null in production.
Well, not sure how are getting data on local server becuse, you are sending MultipartFormData means your POCO object and file buffer. As you may know we can send json object in FromBody but not the files as json. Thus, I am not sure how it working in local and getting null data is logical in IIS Or Azure.
what am I missing in the above implementation?
As explained above, for sending both POCO object and Files as byte or steam we need to use FromForm and beside that, we need to bind our request object as MultipartFormDataContent to resolve your null data on your UploadDocumentsAsync API action.
Required Change For Solution:
WPF:
In your WPF http request please update your request code snippet as following:
var obj = new Request()
{
Uploader = "John Doe",
Documents = new List<Document>
{
new Document()
{
FileName ="I Love Coding.pdf",
Buffer = System.IO.File.ReadAllBytes(#"YourFilePath")
}
}
};
var httpClient = new HttpClient
{
BaseAddress = new("https://YourServerURL")
};
var formContent = new MultipartFormDataContent();
formContent.Add(new StringContent(obj.Uploader), "Uploader");
formContent.Add(new StringContent(obj.Documents[0].FileName), "Documents[0].FileName");
formContent.Add(new StreamContent(new MemoryStream(obj.Documents[0].Buffer)), "Documents[0].Buffer", obj.Documents[0].FileName);
var response = await httpClient.PostAsync("/api/upload", formContent);
if (response.IsSuccessStatusCode)
{
var responseFromAzureIIS = await response.Content.ReadAsStringAsync();
}
Note: Class in WPF side would remain same as before. No changes required.
Asp.net Core Web API:
In asp.net core web API side you should use [FromForm] instead of [FromBody]
So your controller Action would as following:
[Route("")]
public class AppController : ControllerBase
{
[HttpPost]
[Route("api/upload")]
public async Task<IActionResult> UploadDocumentsAsync([FromForm] Request file)
{
if (file.Documents[0].Buffer == null)
{
return Ok("Null File");
}
return Ok("File Received");
}
}
Note: For remote debugging I have checked the logs and for double check I have used a simple conditionals whether file.Documents[0].Buffer == null. I have tested both in local, IIS and Azure and working accordingly.
Update POCO Class in API Project:
For buffer you have used byte for your WPF project but for Web API project update that to IFormFile instead of byte. It should be as following:
public class Document
{
public string FileName { get; set; }
public IFormFile Buffer { get; set; }
}
public class Request
{
public string Uploader { get; set; }
public List<Document> Documents { get; set; }
}
Output:
If you would like to know more details on it you could check our official document here

How to make a PUT request from ASP.NET core mvc to Web API in asp.net core?

I need to save the changes I make in my model through API call in my database. I have checked my API is working fine when I am running it individually on Web. But its giving me an error StatusCode: 405, ReasonPhrase: 'Method Not Allowed'. I am trying to send and object and trying to see whether the request made was completed or not. When I am trying to debug it, it is not sending hit on my API controller.
Here is my model class:
public class Customer
{
[Required]
public Guid CustomerId { get; set; }
public int Age { get; set; }
public int Phone { get; set; }
}
PUT Method in API:
[HttpPut]
[Route("api/[controller]/{customer}")]
public IActionResult EditCustomer(Customer customer)
{
var cust = _customerData.EditCustomer(customer);
if (cust == string.Empty)
{
return Ok();
}
else
{
return new StatusCodeResult(StatusCodes.Status500InternalServerError);
}
}
The method I am using in project to call API:
using (HttpClient client = new HttpClient())
{
client.BaseAddress = new Uri(apiBaseUrl);
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(
new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json")
);
var sum = await client.PutAsJsonAsync("api/Customer/", customer);
if (sum.StatusCode == System.Net.HttpStatusCode.OK)
{
return RedirectToActionPermanent(actionName: "SingIn");
}
else
{
TempData["msg"] = "There is an error";
return View();
}
where baseaddress= {https://localhost:44398/}
EditCustomer Method
public string EditCustomer(Customer customer)
{
try
{
var pro = _customerContext.Customer.Where(e => e.CustomerId == customer.CustomerId).FirstOrDefault();
pro.Age = customer.Age;
pro.Phone = customer.Phone;
pro.Name = customer.Name;
_customerContext.Entry(pro).State = EntityState.Modified;
_customerContext.SaveChanges();
}
catch(Exception e)
{
return e.Message;
}
return string.Empty;
}

You need to fix your action route by removing {Customer}, since you send customer in request body, not as a route value
[Route("~/api/Customer")]
and request
var sum = await client.PutAsJsonAsync("/api/Customer", customer);
or better fix the acttion route name to meaningfull
[Route("~/api/EditCustomer")]
and
var sum = await client.PutAsJsonAsync("/api/EditCustomer", customer);
AsJsonAsync sometimes causes problems
try this code
var json = JsonSerializer.Serialize(customer);
//or if you are using Newtonsoft
var json = JsonConvert.SerializeObject(customer);
var contentData = new StringContent(json, Encoding.UTF8, "application/json");
var response = await client.PutAsync("/api/Customer", contentData);
if (response.IsSuccessStatusCode)
return RedirectToActionPermanent("SingIn");
else
{
TempData["msg"] = "There is an error";
return View();
}
but IMHO I would prefer to use
client.PostAsync("/api/EditCustomer", contentData);
instead of Put.
and added [FromBody] to action
[HttpPost("~/api/EditCustomer")]
public IActionResult EditCustomer([FromBody] Customer customer)

I am no pro in web APIs but I suspect it could be due to the fact that the API expects customer to be in request URL.
Try and change the API route to [Route("api/[controller]")]
This could've been a comment but I don't have enough reputation :)

Integration Testing multipart/form-data c#

I have trouble trying to create an integration test for my post call that accepts a viewmodel that has amongst other values, an IFormFile, which makes this call from an application/json to a multipart/form-data
My IntegrationSetup class
protected static IFormFile GetFormFile()
{
byte[] bytes = Encoding.UTF8.GetBytes("test;test;");
var file = new FormFile(
baseStream: new MemoryStream(bytes),
baseStreamOffset: 0,
length: bytes.Length,
name: "Data",
fileName: "dummy.csv"
)
{
Headers = new HeaderDictionary(),
ContentType = "text/csv"
};
return file;
}
My Test Method
public async Task CreateAsync_ShouldReturnId()
{
//Arrange
using var content = new MultipartFormDataContent();
var stringContent = new StringContent(
JsonConvert.SerializeObject(new CreateArticleViewmodel
{
Title = "viewModel.Title",
SmallParagraph = "viewModel.SmallParagraph",
Url = "viewModel.Url",
Image = GetFormFile()
}),
Encoding.UTF8,
"application/json");
stringContent.Headers.Add("Content-Disposition", "form-data; name=\"json\"");
content.Add(stringContent, "json");
//Act
var response = await httpClient.PostAsync($"{Url}", content);
//Assert
response.StatusCode.ShouldBe(HttpStatusCode.OK);
int id = int.Parse(await response.Content.ReadAsStringAsync());
id.ShouldBeGreaterThan(0);
}
My Controller Method
[HttpPost]
public async Task<IActionResult> CreateArticleAsync([FromForm] CreateArticleViewmodel viewModel)
{
var id = await _service.CreateAsync(viewModel).ConfigureAwait(false);
if (id > 0)
return Ok(id);
return BadRequest();
}
It throws a BadRequest without getting inside the method.

The way you are posting the request contents to the API, in your code, is not correct.
When the API expects a FileInfo in the request payload, posting JSON content never works. You need to send the payload as MultipartFormData and not as JSON.
Consider following example.
This is a an API endpoint which expects and model with FileInfo in it as payload.
[HttpPost]
public IActionResult Upload([FromForm] MyData myData)
{
if (myData.File != null)
{
return Ok("File received");
}
else
{
return BadRequest("File no provided");
}
}
public class MyData
{
public int Id { get; set; }
public string Title { get; set; }
// Below property is used for getting file from client to the server.
public IFormFile File { get; set; }
}
This is pretty much the same API as yours.
Following is the client code which calls the above API with file and other model properties.
var apiURL = "http://localhost:50492/home/upload";
const string filename = "D:\\samplefile.docx";
HttpClient _client = new HttpClient();
// Instead of JSON body, multipart form data will be sent as request body.
var httpContent = new MultipartFormDataContent();
var fileContent = new ByteArrayContent(File.ReadAllBytes(filename));
fileContent.Headers.ContentType = MediaTypeHeaderValue.Parse("multipart/form-data");
// Add File property with file content
httpContent.Add(fileContent, "file", filename);
// Add id property with its value
httpContent.Add(new StringContent("789"), "id");
// Add title property with its value.
httpContent.Add(new StringContent("Some title value"), "title");
// send POST request.
var response = await _client.PostAsync(apiURL, httpContent);
response.EnsureSuccessStatusCode();
var responseContent = await response.Content.ReadAsStringAsync();
// output the response content to the console.
Console.WriteLine(responseContent);
The client code is running from a Console application. So when I run this, the expectation is to get File received message in the console and I am getting that message.
Following is the screen capture of the model content at the API end while debugging it.
And if I am calling this API from postman, it would look like following.
I hope this will help you solve your issue.

Posting object/keyvalue with file upload to asp.net core api

I have been trying to post a file with additonal information to asp.net core 3+ post api. If I send these params individually, it works. However, I want to send the required information at once.
My Model in ASP.Net Core 3.1
public class PostItem
{
public string Title { get; set; }
public IFormFile File { get; set; }
}
The Post API
[HttpPost]
public async Task<IActionResult> Post(PostItem item)
{
try
{
if (item == null)
return BadRequest();
await Task.Delay(TimeSpan.FromMilliseconds(100));
//Do Something here
return Ok();
}
catch (Exception ex)
{
return StatusCode(500, ex.Message + "Internal server error");
}
}
Calling the API from Xamarin client
MultipartFormDataContent content = new MultipartFormDataContent();
var values = new[]
{
new KeyValuePair<string, string>("Title", postItem.Title)
};
foreach(var keyValue in values)
{
content.Add(new StringContent(keyValue.Value), keyValue.Key);
}
foreach (string file in imagePaths)
{
byte[] byteArray = File.ReadAllBytes(file);
content.Add(new ByteArrayContent(byteArray), "file", Path.GetFileName(file));
}
HttpClient client = new HttpClient();
var response = await client.PostAsync(Path.Combine(ApplicationConstants.apiUrl, "item/"), content);
//read response result as a string async into json var
var responsestr = response.Content.ReadAsStringAsync().Result;
I am getting 415 error Unsupported Media Type
The question is how to send the required parameter from Xamarin Client
or how to include FileUpload as part of an object and send it to the
api?

Decorate the input parameter in your post method with a [FromForm] tag to bind to the form.
public async Task<IActionResult> Post([FromForm] PostItem item)
{
}
This is assuming that your PostItem class matches the form you are posting. Adding [FromForm] should at least fix the 415.

How to receive a file in ASP.NET Core controller

I want to send an image with C# HttpClient, receive it in ASP.NET Core controller and save it to disk. I tried various methods but all i'm getting in controller is null reference.
My http client:
public class HttpClientAdapter
{
private readonly HttpClient _client;
public HttpClientAdapter()
{
_client = new HttpClient();
}
public async Task<HttpResponse> PostFileAsync(string url, string filePath)
{
var requestContent = ConstructRequestContent(filePath);
var response = await _client.PostAsync(url, requestContent);
var responseBody = await response.Content.ReadAsStringAsync();
return new HttpResponse
{
StatusCode = response.StatusCode,
Body = JsonConvert.DeserializeObject<JObject>(responseBody)
};
}
private MultipartFormDataContent ConstructRequestContent(string filePath)
{
var content = new MultipartFormDataContent();
var fileStream = File.OpenRead(filePath);
var streamContent = new StreamContent(fileStream);
var imageContent = new ByteArrayContent(streamContent.ReadAsByteArrayAsync().Result);
imageContent.Headers.ContentType = MediaTypeHeaderValue.Parse("multipart/form-data");
content.Add(imageContent, "image", Path.GetFileName(filePath));
return content;
}
}
and controller:
[Route("api/files")]
public class FilesController: Controller
{
private readonly ILogger<FilesController> _logger;
public FilesController(ILogger<FilesController> logger)
{
_logger = logger;
}
[HttpPost]
public IActionResult Post(IFormFile file)
{
_logger.LogInformation(file.ToString());
return Ok();
}
}
As i mentioned above, the IFormFile object i'm getting in the controller is null reference. I tried adding [FromBody], [FromForm], tried creating class with two properties: one of type string and one with type IFormFile, but nothing works. Also instead of sending file with C# HttpClient i used Postman - same thing happens.
Does anyone know solution for this problem? Thanks in advance.

The name of the form field must match the property name:
content.Add(imageContent, "file", Path.GetFileName(filePath));
file instead of image, since you use file in
public IActionResult Post(IFormFile file)
{
}