aspnet web api how to validate using modelstate in multipart form data? - asp.net-web-api

Question

I am new for using asp net web api.
I want to create UploadDocument feature in my web api.
so, I create this way.
From Client
api.post('vendor/UploadDocument', formData, { headers: { 'Content-Type': 'multipart/form-data' } })
Controller
public class VendorController : ApiController {
[HttpPost]
public HttpResponseMessage UploadDocument()
{
try
{
if (!Request.Content.IsMimeMultipartContent())
throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);
var request = HttpContext.Current.Request;
var model = new UploadDocumentViewModel();
model.field1 = request.Form["field1"];
model.field2 = request.Form["field2"];
model.Document = request.Files["Document"];
if (ModelState.IsValid)
{
return Request.CreateResponse(HttpStatusCode.OK);
}
else //ModelState is not valid
{
return Request.CreateResponse(HttpStatusCode.BadRequest);
}
}
catch (Exception exception)
{
return Request.CreateResponse(HttpStatusCode.InternalServerError);
}
}
}
Model
public class UploadDocumentViewModel
{
[Required]
public string field1 { get; set; }
[Required]
public int field2 { get; set; }
[Required]
public HttpPostedFile Document { get; set; }
}
My problem is, in controller ModelState always empty.
I have tried to add code
Validate(model);
if (ModelState.IsValid)...
but it didn't work too.
can someone have any idea for validating model data annotation in multipart form data ?

Answer 1

try clear model state before validate
ModelState.Clear();
this.Validate(model);
if (ModelState.IsValid) {
}
Check this answer : Custom DataAnnotation

Answer 2

Your method should look like this:
public class VendorController : ApiController {
[HttpPost]
public IHttpActionResult UploadDocument(UploadDocumentViewModel viewModel)
{
try
{
if (!Request.Content.IsMimeMultipartContent())
return StatusCode(HttpStatusCode.UnsupportedMediaType);
if (viewNodel == null)
return BadRequest("Model is empty");
var field1 = viewModel.field1;
var field2 = viewModel.field2;
var documents = viewModel.document;
if (ModelState.IsValid)
{
return Ok();
}
else
{
return BadRequest(ModelState);
}
}
catch (Exception exception)
{
return InternalServerError(exception);
}
}
}
I prefer to passing some of those validations in action filters, to make your methods cleaner (try/catch, modelstate).
If you will have some problems with model binding, you can implement your custom model binder.