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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

Can't get response from Ecom Express API when using VerveLogic.HttpHandler

I have to integrate Ecom express shipping API in my code. This api is for pre generation of AWB Number at the time of order. Here is the document instruction to integrate shipping api :
Test Server URL:http://staging.ecomexpress.in/apiv2/fetch_awb/
Test Server Credentials: Username: ecomexpress Password: Ke$3c#4oT5m6h#$
Sample Request Body :
For PPD
username=ecomexpress&password=Ke$3c#4oT5m6h#$&count=1&type=PPD
For COD
username=ecomexpress&password=Ke$3c#4oT5m6h#$&count=1&type=COD
This API works fine with postman and generate AWB number also, But trying with C# code gives null object.
Check here the code I am using :
var client = new HttpHandler.Client("http://staging.ecomexpress.in/apiv2/fetch_awb/");
var newUrl = "http://staging.ecomexpress.in/apiv2/fetch_awb/?username=ecomexpress&password=Ke$3c#4oT5m6h#$&count=1&type=PPD";
var data = client.PostData<dynamic>(newUrl, new { username= "ecomexpress", password= "Ke$3c#4oT5m6h#$", count=1,type= "PPD" });
if (data!=null){ // do some stuff here }
I am using http handler nuget package (https://www.nuget.org/packages/VerveLogic.HttpHandler/)
Please help or suggest a way in which I can get AWB Number using C# code.Also check the postman and document instruction here :

You can easily make this work using HttpClient and Newtonsoft.Json, so might be something with that particular library not sending the parameters as form-urlencoded.
using (var client = new HttpClient())
{
var content = new FormUrlEncodedContent(new[]
{
new KeyValuePair<string, string>("username", "ecomexpress"),
new KeyValuePair<string, string>("password", "Ke$3c#4oT5m6h#$"),
new KeyValuePair<string, string>("count", "1"),
new KeyValuePair<string, string>("type", "PPD"),
});
var response = await client.PostAsync("http://staging.ecomexpress.in/apiv2/fetch_awb/", content);
var body = await response.Content.ReadAsStringAsync();
var responseObject = JsonConvert.DeserializeObject<ResponseObject>(body);
}
Where ResponseObject is:
public class ResponseObject
{
[JsonProperty("reference_id")]
public int ReferenceId { get; set; }
[JsonProperty("success")]
public string SuccessText { get; set; }
[JsonIgnore]
public bool Success => SuccessText.Equals("yes", StringComparison.OrdinalIgnoreCase);
[JsonProperty("awb")]
public int[] Awb { get; set; }
}

What is wrong with this request (Azure management.azure.com API)

I am trying to get this azure API to work:
https://learn.microsoft.com/en-us/rest/api/machinelearning/webservices/createorupdate
The following code runs a GET request which returns successfully (200 OK and return body), but the Put request to the exact same uri at the bottom fails with a 400 "Bad request".
The code inbetween basically just unwraps the json output of the first request and tried to send the same unchanged data in the input format of the PUT on the same uri.
Could anyone help me see why this fails?
var httpClient = new HttpClient();
httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);
HttpResponseMessage response = await httpClient.GetAsync($"https://management.azure.com/subscriptions/{subscriptionId}/resourceGroups/{resourceGroup}/providers/Microsoft.MachineLearning/webServices/{serviceName}?api-version=2016-05-01-preview");
var json = await response.Content.ReadAsStringAsync();
var f = JsonConvert.DeserializeObject<WebService>(json);
var requestBody = new RequestBody()
{
location = f.Location,
name = f.Name,
tags = f.Tags,
properties = f.Properties
};
var jsoncontent = JsonConvert.SerializeObject(requestBody, Formatting.None);
var content = new StringContent(jsoncontent, Encoding.UTF8, "application/json"); //tried simpler things like "{\"location\":\"West Europe\"}" with no result
var response2 = await httpClient.PutAsync($"https://management.azure.com/subscriptions/{subscriptionId}/resourceGroups/{resourceGroup}/providers/Microsoft.MachineLearning/webServices/{serviceName}?api-version=2016-05-01-preview", content, new JsonMediaTypeFormatter());
// last line returns a 400 bad request only.
And then I use this custom object;
private class RequestBody
{
public string location { get; set; }
public string name { get; set; }
public WebServiceProperties properties { get; set; }
public IDictionary<string, string> tags { get; set; }
}

It seems it was one of those obvious things.
The ", new JsonMediaTypeFormatter()" snippet at the end ruined it. Removing it fixed the issue and it returns 200 OK without it.

Creating a JSON object in ASP.Net

I am trying to create a JSON object in a .Net 5 application. The default options I am presented with are Microsoft.AspNet.Mvc.Formatters.Json, Microsoft.Extensions.Configuration.Json, and Newtonsoft.Json when I use the Visual Studio 2015 Qucik Actions on Json. My understanding is that Configuration.Json is for reading form the appsettings.json so it probably is not what I would use to create a JSON object. I can't find any real information on Formatters.Json, how to use it, or what it's intended use it. Newtonsoft.Json is will documented but is it better over the Formatters.Json? Which of the two should I be using?

Taken directly from ASP.NET Core 1 tests
var expected = Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(new { foo = "abcd" }));
Also taken from the tests and slightly modified, call it with HttpClient to see how to send your json string to the server.
var response = await Client.PostAsync(
"http://localhost/api/ActionUsingSpecificFormatters",
new StringContent(yourJsonContent, Encoding.UTF8, "application/json"));
As per Newtonsoft you can simply encode, then do whatever you want after that.
Product product = new Product();
product.Name = "Apple";
product.ExpiryDate = new DateTime(2008, 12, 28);
product.Price = 3.99M;
product.Sizes = new string[] { "Small", "Medium", "Large" };
string output = JsonConvert.SerializeObject(product);
//{
// "Name": "Apple",
// "ExpiryDate": "2008-12-28T00:00:00",
// "Price": 3.99,
// "Sizes": [
// "Small",
// "Medium",
// "Large"
// ]
//}
Product deserializedProduct = JsonConvert.DeserializeObject(output);
Putting it all together - I just tested this. Keep in mind this is a real generic pass through test from MVC 6 (ASP.NET 5 ie ASP.NET Core 1) :)
[HttpGet]
public async Task<string> Get()
{
var client = new HttpClient();
var customer = new Customer() { Name = "Schmo", Address = "1999 Purple Rain St" };
var customerJson = JsonConvert.SerializeObject(customer);
var response = await client.PostAsync(
"http://localhost:4815/api/Customer",
new StringContent(customerJson, Encoding.UTF8, "application/json"));
//just some template output to test which I'm getting back.
string resultJson = "{ 'Name':'adam'}";
if (response.StatusCode == HttpStatusCode.OK)
{
resultJson = await response.Content.ReadAsStringAsync();
var updatedCustomer = JsonConvert.DeserializeObject(resultJson);
}
return resultJson;
}
public class Customer
{
public string Name { get; set; }
public string Address { get; set; }
}

I would use Json.Net to create the JSON payloads for sure (Afterall, Microsoft does for Web Api).
Nuget Package Source:
Install-Package Newtonsoft.Json
Here is an example. If you want to call a REST api that returns a product when you make a GET call then you might do something like this.
public static class Main
{
string url = "https://TheDomainYouWantToContact.com/products/1";
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);
request.Method = "GET";
request.ContentType = "application/json";
request.Accept = "application/json";
var httpResponse = (HttpWebResponse)request.GetResponse();
var dataStream = httpResponse.GetResponseStream();
var reader = new StreamReader(dataStream);
var responseFromServer = reader.ReadToEnd();
reader.Close();
dataStream.Close();
// This is the code that turns the JSON string into the Product object.
Product productFromServer = JsonConvert.Deserialize<Product>(responseFromServer);
Console.Writeline(productFromServer.Id);
}
// This is the class that represents the JSON that you want to post to the service.
public class Product
{
public string Id { get; set; }
public decimal Cost { get; set; }
public string Name { get; set; }
public string Description { get; set; }
}
The exact same method can be used for POST and PUT as well.
You can use 3rd party assemblies to make this super easy too. We are the authors of DynamicApis.Api
Install-Package DynamicApis.Api
The code to make the same request using this client would be:
public static class Main
{
RestClient client = new RestClient();
string url = "https://YourDomain.com/products/1";
var productFromServer = client.Get<Product>(url);
Console.Writeline(productFromServer.Id);
}

you should use NewtonSoft.Json if you need to serialize objects as json

You shouldn't have to do anything special to send back Json data. The default output formatter is already Json, and if your Startup.cs file is somewhat normal, you should have a line similar to this:
services.AddMvc();
By default, this already contains the Json formatter, and your controller should autonegotiate the return type based on what the browser asked. So a controller like the following should work (taken from this Github issue, which contains some information on why/how this work):
public class ValuesController : ApiController
{
public SomeClass Get()
{
return new SomeClass();
}
public SomeClass Post([FromBody] SomeClass x)
{
return x;
}
}

web api receive object with null variables

I have webforms asp and web api. In web forms I try send to web api object of class this way:
HttpClient client = HttpClientHeader("", login, ClassMd5Calc.CalculateMd5Hash(password));
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
UserTariff userTariff = new UserTariff();
userTariff.Login = "some value";
userTariff.Password = "some value";
userTariff.TariffName = "some value";
var json = new JavaScriptSerializer().Serialize(userTariff);
StringContent content = new StringContent(json);
content.Headers.ContentType = new MediaTypeHeaderValue("text/json");
HttpResponseMessage response = client.PostAsync("api/ChangeTariff/", content).Result;
This is my class (exist in data contract solution, so both project are use this class).
[Serializable]
public class UserTariff
{
public String Login { get; set; }
public String Password { get; set; }
public String TariffName { get; set; }
public decimal Balance { get; set; }
}
My web api receive package, but all field are null. What's wrong? How it's fix?
public class ChangeTariffController : ApiController
{
public void Post([FromBody] UserTariff mes)
{
//mes exist, but his property are null: mes.Login=null; mes.Password=null and e.t.c. but need value: "some value"
UPDATE 1.
I also tryed this code, but it show same error:
var content = new ObjectContent<UserTariff>(new UserTariff(), new JsonMediaTypeFormatter());
content.Headers.ContentType = new MediaTypeHeaderValue("text/json");
HttpResponseMessage response = client.PostAsync("api/ChangeTariff/", content).Result;

You can set the object content instead of the string content and should be using json media type formatter. This should fix the null bound variable in web api.
Also, use the newton soft json lib to convert the object to json.