Receiving json as string always null

Question

With an endpoint like this:

        [HttpPost("[action]")]
        public async Task<ActionResult> Import([FromBody]string request)
        {
            var list = JsonConvert.DeserializeObject<List<RequestQuote>>(request);

            return NoContent();
        }

request always seems to be null. It worked for a little while earlier today but not sure what changed.

Here is the client side where I do the call.

  var json = JsonConvert.SerializeObject(payload);
  var data = new StringContent(json, Encoding.UTF8, "application/json");
  var response = client.PostAsJsonAsync($"{endpoint}/api/v1.0/BatchImport/Import", data);

Payload is a List

Even when using

Import([FromBody] List<RequestQuote> request)

I get the same issue.

Hook up something like Fiddler and inspect the HTTP request sent to the server, if it's malformed then that's your problem, if not then update the question with the request — MindSwipe, Dec 23 '21 at 20:19
@MindSwipe, just tried with fiddler, looks like only the headers are there. But when I step through the code payload populates as it should — Bike_dotnet, Dec 23 '21 at 20:46
What framework + version are you using? [tag:asp.net-core-webapi] or [tag:asp.net-web-api]? Might you please [edit] your question to [tag](https://stackoverflow.com/help/tagging) it with the appropriate framework? You're more likely to get help if you do. — dbc, Dec 24 '21 at 14:45

Serge · Accepted Answer · 2021-12-23T22:20:37.600

There is a bug in the code, the data is serialized twice, the second time when you use PostAsJsonAsync. Try this

var json = JsonConvert.SerializeObject(payload);

var data = new StringContent(json, Encoding.UTF8, "application/json");

var response = await client.PostAsync($"{endpoint}/api/v1.0/BatchImport/Import", data);

if (response.IsSuccessStatusCode)
    {
        var stringData = await response.Content.ReadAsStringAsync();
        var result = JsonConvert.DeserializeObject<object>(stringData);
    }

and action should be

public async Task<ActionResult> Import([FromBody] List<RequestQuote> request)

score 1 · Answer 2 · answered Dec 23 '21 at 20:41

If your controller has the [ApiController] attribute, you can put the data type you want to parse as the parameter of the method. I believe what is happening is that your program is trying to parse the JSON to a string type, which isn't what you want. You can try the code below, which should achieve what you're looking for.

[HttpPost("[action]")]
public async Task<ActionResult> Import([FromBody]List<RequestQuote> list)
{
    // The parsed object should now be available here as "list"
    return NoContent();
}

Alternatively, this post suggests pulling the body of the request directly. Either solution should be valid.

score 0 · Answer 3 · answered Feb 22 '23 at 12:12

0

json is coming properly for me. but after staticContent, I think it breaks down. The model I sent to Service is null. Here are my project codes : How can I send Model to service in xamarin forms. Something wrong while posting?

answered Feb 22 '23 at 12:12

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Receiving json as string always null

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