Develop Reference

Send a JSON request to another web site from C# code behind in an ASP.NET MVC project

I'm working with ASP.NET MVC (backend being C#) and I'm trying to send a json that would look like this :
{
"store_id": "store3",
"api_token": "yesguy",
"checkout_id": "UniqueNumber",
"txn_total": "10.00",
"environment": "qa",
"action": "preload"
}
to another web site, suppose it's something like:
https://TestGate.paimon.com/chkt/request/request.php
Through some research I found this :
Send json to another server using asp.net core mvc c#
Looks good but I'm not working in core, my project is just normal ASP.NET MVC. I don't know how to use json functions to send it to a web site.
Here is what I tried (updated after inspired by Liad Dadon answer) :
public ActionResult Index(int idInsc)
{
INSC_Inscription insc = GetMainModelInfos(idinsc);
JsonModel jm = new JsonModel();
jm.store_id = "store2";
jm.api_token = "yesguy";
jm.checkout_id = "uniqueId";
jm.txn_total = "123.00";
jm.environment = "qa";
jm.action = "preload";
var jsonObject = JsonConvert.SerializeObject(jm);
var url = "https://gatewayt.whatever.com/chkt/request/request.php";
HttpClient client = new HttpClient();
var content = new StringContent(jsonObject, System.Text.Encoding.UTF8, "application/json");
System.Threading.Tasks.Task<HttpResponseMessage> res = client.PostAsync(url, content);
insc.response = res.Result; // This cause an exeption
return View(insc);
}
When ths Json is posted correctly, the other web site will answer me with is own Json :
{
"response" :
{
"success": "true",
"ticket": "Another_Long_And_Unique_Id_From_The_Other_Web_Site"
}
}
What I need to do is retreive this Json answer, once I have it, the rest is piece of cake.
Infos :
After the PostAsync function, var res contains this :

It looks like you might not be correctly handling an asynchronous task — the WaitingForActivation message you’re seeing, rather than being a response from our API, is in fact the status of your task.
The task is waiting to be activated and scheduled internally by the .NET Framework infrastructure.
It seems you might need to await⁽²⁾ the task to ensure it completes or access the response with await client.PostAsync(url, content);. for adding await you need to add async to controller⁽¹⁾ action.
public async Task<ActionResult> Index(int idInsc) //Change here [1]
{
INSC_Inscription insc = GetMainModelInfos(idinsc);
JsonModel jm = new JsonModel();
jm.store_id = "store2";
jm.api_token = "yesguy";
jm.checkout_id = "uniqueId";
jm.txn_total = "123.00";
jm.environment = "qa";
jm.action = "preload";
var jsonObject = JsonConvert.SerializeObject(jm);
var url = "https://gatewayt.whatever.com/chkt/request/request.php";
HttpClient client = new HttpClient();
var content = new StringContent(jsonObject, System.Text.Encoding.UTF8, "application/json");
System.Threading.Tasks.Task<HttpResponseMessage> res = await client.PostAsync(url, content); //Change here [2]
insc.response = res.Result; // This cause an exeption
return View(insc);
}

This is how I would post a JSON object to somewhere using Newtonsoft.Json package, HttpClient and StringContent classes:
using Newtonsoft.Json;
var object = new Model
{
//your properties
}
var jsonObject = JsonConvert.SerializeObject(object);
var url = "http://yoururl.com/endpoint"; //<- your url here
try
{
using HttpClient client = new();
var content = new StringContent(jsonObject , Encoding.UTF8,
"application/json");
var res = await client.PostAsync(url, content);
}
Please make sure your function is async and that you await the client.PostAsync fucntion.

If someone is wondering how I finally pulled it off (with other's help) here it is :
var url = "https://gatewayt.whatever.com/chkt/request/request.php";
HttpClient client = new HttpClient();
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
var content = new StringContent(jsonObject, System.Text.Encoding.UTF8, "application/json");
var res = await client.PostAsync(url, content);
var jsonRes = await res.Content.ReadAsStringAsync();
This line is important var jsonRes = await res.Content.ReadAsStringAsync(); the object jsonRes will be a string value, which is actually the response. The var res will only be the status of the response, not the actual response.

Calling Get Request with Json Body using httpclient

I came with an issue this morning where the Api which I am calling is a Get Method but to get Get the Data from it I had to send the json body this is working good when I am testing it in the post man but I am not able to implement it in my project where I am calling this using HttpClient
here is the screenshot of post
It also have a bearer token which I pass in Authorization
Now when I am try to implement this at client side here is my code
var stringPayload = JsonConvert.SerializeObject(json);
var client = new HttpClient();
var request = new HttpRequestMessage
{
Method = HttpMethod.Get,
RequestUri = new Uri("https://myapiendpoint/serviceability/"),
Content = new StringContent(stringPayload, Encoding.UTF8, "application/json"),
};
var response = await client.SendAsync(request).ConfigureAwait(false);
response.EnsureSuccessStatusCode();
var responseBody = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
when I call this method using this code I get
System.Net.HttpStatusCode.MethodNotAllowed - Status code 405
I also tried changing this line
Method = HttpMethod.Get to Method = HttpMethod.Post
but still getting same error
I know this is bad implementation at API Side the request ideally should be POST but changing this is not in my hand and hence need to find the solution

almost search all over and trying all the variant of using GET Method finally the solution which worked for me in this case was this
var client = new HttpClient();
client.BaseAddress = new Uri("https://baseApi/");
client.DefaultRequestHeaders.Accept.Add(
new MediaTypeWithQualityHeaderValue("application/json"));
client.DefaultRequestHeaders.Add("Authorization", string.Format("Bearer {0}", token));
var query = new Dictionary<string, string>
{
["pickup_postcode"] = 400703,
["delivery_postcode"] = 421204,
["cod"] = "0",
["weight"] = 2,
};
var url = "methodurl";
var response = await client.GetAsync(QueryHelpers.AddQueryString(url, query));
var responseBody = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
return JsonConvert.DeserializeObject<MyModel>(responseBody);
Got QueryHelpers from Microsoft.AspNetCore.WebUtilities package

Problem calling the prediction endpoint uploading an image using rest sharp for the Microsoft custom vision API cognitive service

I am trying to upload an image to the Microsoft custom vision API prediction endpoint using Restsharp, I am trying to use the AddFile method but I am getting a BadRequest as the result, here is the code I am using
public IRestResponse<PredictionResponse> Predict(string imageFileName)
{
var file = new FileInfo(imageFileName);
var serviceUrl = ConfigurationManager.AppSettings["api.custom-vision.prediction.url.file"];
var serviceKey = ConfigurationManager.AppSettings["api.custom-vision.key"];
var client = new RestClient(serviceUrl);
var request = new RestRequest(Method.POST);
request.AddHeader("Content-Type", "application/octet-stream");
request.AddHeader("Prediction-Key", serviceKey);
request.AddFile(file.Name, file.FullName);
var response = client.Execute<PredictionResponse>(request);
return response;
}
When I execute the method I am getting the following response back from the service
{
"code": "BadRequestImageFormat",
"message": "Bad Request Image Format, Uri: 1062fe0480714281abe2daf17beb3ac5"
}

After looking for ways in the restsharp documentation to properly upload a file, I came to the solution that it needs to be passed as parameter with an array of bytes with the parameter type of ParameterType.RequestBody
Here is the example of the method that actually works
public IRestResponse<PredictionResponse> Predict(string imageFileName)
{
var file = new FileInfo(imageFileName);
var serviceUrl = ConfigurationManager.AppSettings["api.custom-vision.prediction.url.file"];
var serviceKey = ConfigurationManager.AppSettings["api.custom-vision.key"];
var client = new RestClient(serviceUrl);
var request = new RestRequest(Method.POST);
request.AddHeader("Content-Type", "application/octet-stream");
request.AddHeader("Prediction-Key", serviceKey);
request.AddParameter("content", File.ReadAllBytes(file.FullName), ParameterType.RequestBody);
var response = client.Execute<PredictionResponse>(request);
return response;
}

why RestSharp Request method Change from POST to GET?

I am using RestSharp to post some data to a url. I am monitoring this operation using fiddler. when I use Simple .net HttpClient with this code:
using (var client = new HttpClient())
{
var values = new Dictionary<string, string> {
{ "par1", "1395/11/29" },
{ "par2", "2" }};
var content = new FormUrlEncodedContent(values);
var response = await client.PostAsync("http://someurl.com/resource", content);
var responseString = await response.Content.ReadAsStringAsync();
}
every thing is good and this return true result. but when i try to use RestSharp with this code:
RestSharp.RestRequest request = new RestSharp.RestRequest("/resource");
request.AddParameter("par1", val, RestSharp.ParameterType.RequestBody);
request.AddParameter("par2", val, RestSharp.ParameterType.RequestBody);
request.AddHeader("Origin", "http://someurl.com");
request.Method = RestSharp.Method.POST;
RestSharp.RestClient client = new RestSharp.RestClient("http://someurl.com");
var response = client.Execute(request);
then fiddler show me the request sent by GET method instead of POST?
I check another time my fiddler and found this issue:
Content-Type: par1
why this is happening for me?

Change your ParameterType argument to GetOrPost and it will work
request.AddParameter("par1", val, RestSharp.ParameterType.GetOrPost);
request.AddParameter("par2", val, RestSharp.ParameterType.GetOrPost);

Initialize Request as POST with JSON.
var client = new RestClient(PreUri);
var request = new RestRequest(Uri, Method.POST) {RequestFormat = DataFormat.Json};
Add object in body
request.AddBody(obj);
Execute
var cancellationTokenSource = new CancellationTokenSource();
var response = await client.ExecuteTaskAsync(request, cancellationTokenSource.Token);

I was stupidly doing mistake to call "client.Get" instead of "client.Post". May be this post helps other.
var client = new RestClient("https://someservice.com");
var request = new RestRequest("/token/", Method.POST, DataFormat.Json).AddJsonBody(SomeObject);
var response = client.Get(request);
I was expecting this code to make POST request. Because i specified it as Method.POST.
But after a few hours, i saw my mistake. Yeas i was specifying the method. But just after i am calling client.Get(request); This changes the metod to GET.
So, the right way to use POST request is like follows:
var client = new RestClient("https://someservice.com");
var request = new RestRequest("/token/", DataFormat.Json).AddJsonBody(SomeObject);
var response = client.Post(request);

Posting form submissions with the KOBO REST API

I'm having a little trouble posting form submissions from C# to a KOBO Server (https://kf.kobotoolbox.org). The response I get is 'Bad Gateway'.
Here's my code:
var client = new RestClient("https://kc.kobotoolbox.org/api/v1/submissions");
//var client = new RestClient("https://kc.kobotoolbox.org/api/v1/forms/{pk}/labels");
client.Authenticator = new HttpBasicAuthenticator("a_user", "alpha9876");
//client.AddDefaultUrlSegment("pk", "31037");
//client.AddDefaultUrlSegment("tags", "tag1, tag2");
// client.AddDefaultUrlSegment("format", "xls");
//client.AddDefaultUrlSegment("url", "https://kc.kobotoolbox.org/api/v1/projects/1");
//client.AddDefaultUrlSegment("owner", "https://kc.kobotoolbox.org/api/v1/users/ona");
//client.AddDefaultUrlSegment("name", "project 1");
//client.AddDefaultUrlSegment("date_created", "2013-07-24T13:37:39Z");
//client.AddDefaultUrlSegment("date_modified", "2013-07-24T13:37:39Z");
var request = new RestRequest(Method.POST);
IRestResponse response = client.Execute(request);
request.AddHeader("header", "xml");
request.Resource = "C:\\Users\\Susan\\Desktop\\xmltest\\form_linkage_parentform.xml";
Could anyone help with a sample snippet of what the C# code for making this POST HTTP request would probably look like? Based on this: https://kc.kobotoolbox.org/api/v1/
Thank you!

I finally managed to do it using CSV files (https://kc.kobotoolbox.org/api/v1/forms) as follows:
var client = new RestClient("https://kc.kobotoolbox.org/api/v1/forms/{pk}/csv_import");
client.Authenticator = new HttpBasicAuthenticator("user_name", "password");
client.AddDefaultUrlSegment("pk", "31045");
string file_path = Server.MapPath("~/myform.csv");
var request = new RestRequest(Method.POST);
request.AddFile("csv_file", file_path);
IRestResponse response = client.Execute(request);