Send JSON data in http post request C#

Question

I'm trying to send a http post request in JSON format which should look like this:

{ 
"id":"72832",
"name":"John"
}

I have attempted to do it like below but if I am correct this is not sending a request in json format.

var values = new Dictionary<string,string>
{
    {"id","72832"},
    {"name","John"}
};

using (HttpClient client = new HttpClient())
{
    var content = new FormUrlEncodedContent(values);
    HttpResponseMessage response = await client.PostAsync("https://myurl",content);
    // code to do something with response
}

How could I modify the code to send the request in json format?

TylerH · Accepted Answer · 2023-09-19 21:11:31Z

12

try this

using (var client = new HttpClient())
{

    var contentType = new MediaTypeWithQualityHeaderValue("application/json");
    var baseAddress = "https://....";
    var api = "/controller/action";
    client.BaseAddress = new Uri(baseAddress);
    client.DefaultRequestHeaders.Accept.Add(contentType);
    
    var data = new Dictionary<string,string>
    {
        {"id","72832"},
        {"name","John"}
    };
    
    //or you can use an anonymous type
    //var data = new 
    //{
    //  id = 72832,
    //  name = "John"
    //};
    
    var jsonData = JsonConvert.SerializeObject(data);
    var contentData = new StringContent(jsonData, Encoding.UTF8, "application/json");
    
    var response = await client.PostAsync(api, contentData);
    
    if (response.IsSuccessStatusCode)
    {
        var stringData = await response.Content.ReadAsStringAsync();
        var result = JsonConvert.DeserializeObject<object>(stringData);
    }
}

If the request comes back with JSON data in the form

{ "return":"8.00", "name":"John" }

you have to create result model

public class ResultModel
{
    public string Name { get; set; }
    public double Return { get; set; }
}

and code

if (response.IsSuccessStatusCode)
{
    var stringData = await response.Content.ReadAsStringAsync();
    var result = JsonConvert.DeserializeObject<ResultModel>(stringData);
   
    double value = result.Return;
    string name = Result.Name;
}

edited Sep 19, 2023 at 21:11

TylerH

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answered Aug 10, 2021 at 0:44

Serge

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8 Comments

Gazdini9991 Over a year ago

Thank you for your response! If the request comes back with Json data in the form ```` { "return":"8.00", "name":"John" } ```` How can I access the value associated to return (in this case "8.00") and store it as a string?

Gazdini9991 Over a year ago

The code is not quite working as expected - when I am debugging the code var json data looks as follows: "{\"id\":\"72832\",\"name\":\"John\"}" and then contentData doesn't seem to be taking the right form, its value is {System.Net.Http.StringContent} and inside it is Headers, Static members and Non-Public members - I can't seem to find my jsondata anywhere inside the contentData

Serge Over a year ago

@SJ9991 What is the problem?You should not care what is content looks like, Did you check the values inside of the API ? this code was used many many times by many peopele and nobody didn't have any problem.

Gazdini9991 Over a year ago

The code is failing on the var response = ...PostAsync(..) stage, the jsonData looks to be in the correct form when I am debugging the code which is why I thought it may be the contentData. When I catch the error as Exception ex, inside the ExceptionState it says "Unable to evaluate expression because the code is optimized or a native frame is on top of the call stack" and the HResult is -2146233040

Serge Over a year ago

What is your url when you call PostAsync? It can be wrong url or an API errro. Could you post your API too?

|

jallmen · Accepted Answer · 2021-08-10 08:07:11Z

2

I would start off by using RestSharp.

dotnet add package RestSharp

Then you can send requests like this:

public async Task<IRestResult> PostAsync(string url, object body)
{
    var client = new RestClient(url);
    client.Timeout = -1;

    var request = new RestRequest(Method.Post);
    request.AddJsonBody(body);

    var response = await client.ExecuteAsync(request);
    return response;
}

Just pass in your dictionary as the body object - I would recommend creating a DTOS class to send through though.

Then you can get certain aspects of the RestResponse object that is returned like:

var returnContent = response.Content;
var statusCode = response.StatusCode;

answered Aug 10, 2021 at 8:07

jallmen

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