I am separating some code out of a website and after copying the code behind for the particular page in question, I'm getting an error on the PostAsJsonAsync() line of code:
HttpResponseMessage response = await client.PostAsJsonAsync("api/...", user);
which is in this using statement (added headers as well)
using System;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Net.Mail;
using System.Threading.Tasks;
//...
using (var client = new HttpClient())
{
client.BaseAddress = new Uri("WebServiceAddress");
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage response = await client.PostAsJsonAsync("api/...", user);
if (response.IsSuccessStatusCode)
{
const string result = "Thank you for your submission.";
return result;
}
//...
}
The error I get says
Error 4 'System.Net.Http.HttpClient'
does not contain a definition for 'PostAsJsonAsync' and no extension
method 'PostAsJsonAsync' accepting a first argument of type 'System.Net.Http.HttpClient'
could be found (are you missing a using directive or an assembly reference?)
even though it works in the former project and was copied straight over from that project in its entirety. Did I forget to add something?
I appreciate any help on the matter.
You will have to add following dependency,
System.Net.Http.Formatting.dll
It should be there in extensions -> assembly.
or
You can add Microsoft.AspNet.WebApi.Client nuget package
I wrote my own extension method as I believe that method is only for older .NET api, and used Newtonsoft JSON serializer:
// Extension method to post a JSON
public static async Task<HttpResponseMessage> PostAsJsonAsync(this HttpClient client, string addr, object obj)
{
var response = await client.PostAsync(addr, new StringContent(
Newtonsoft.Json.JsonConvert.SerializeObject(obj),
Encoding.UTF8, "application/json"));
return response;
}
I had the same error, even with the respective Nuget package installed. What helped me is just this using statement:
using System.Net.Http;
Related
Ive removed sensitive data but am getting this issue when trying to make an API request, although I have the relevant packages installed. Why would this be?
using System;
using IronXL;
using RestClient;
using Rest;
using Newtonsoft;
using RestSharp;
using RestSharp.Authenticators;
using RestSharp.Validation;
public static void APIRequest()
{
var client = new RestClient("");
client.Timeout = -1;
var request = new RestRequest(Method.POST);
request.AddHeader("Accept", "application/vnd.evolutionx.v1+json");
request.AddHeader("Authorization", "Bearer ");
request.AddHeader("Content-Type", "application/json");
IRestResponse response = client.Execute(request);
Console.WriteLine(response.Content);
}
This line:
using RestClient;
makes RestClient a known namespace in your code. C# will then assume that any references to RestClient refer to that namespace, unless you specifically say otherwise.
If RestClient really is a class, then you'll have to specify its namespace in front of it
e.g.
new RelevantNamespace.RestClient("")
to differentiate it from the namespace. I would guess it's the RestClient class from RestSharp, so probably new RestSharp.RestClient("") makes sense.
On the other hand, you said in the comments that the RestClient namespace is greyed out in the IDE. This means you are you not using anything from it. Therefore to solve your problem can you can simply remove that using RestClient; statement from your file.
You probably also don't need the RestClient.net package in general, since RestSharp already does a very similar job.
As you're using RestClient.net, it looks like you need to instantiate using
var client = new RestClient.Net.Client();
So the class is Client.
The details of how to setup the class is here:
https://github.com/MelbourneDeveloper/RestClient.Net
Note the how to start
var client = new Client(new NewtonsoftSerializationAdapter(), new Uri("https://restcountries.eu/rest/v2/"));
var response = await client.GetAsync<List<RestCountry>>();
or using .NET Core serialisation
var client = new Client(new Uri("https://restcountries.eu/rest/v2/"));
var response = await client.GetAsync<List<RestCountry>>();
I have this error in visual studio. It is PCL I have added my solution and I am trying to use Windows.Web.Http.HttpClient and not the one in System.net.http. I have a reference for "Windows" but gets the following error by the GetAsync call:
'IAsyncOperationWithProgress' does not contain a definition for 'GetAwaiter' and no extension method 'GetAwaiter' accepting a first argument of type 'IAsyncOperationWithProgress' could be found (are you missing a using directive for 'System'?)
"using System;" is in the top of the file. In many examples like the following I can see it should work but I must be missing something: https://learn.microsoft.com/en-us/uwp/api/windows.web.http.httpclient
using (HttpClient client = new HttpClient())
{
var response = await client.GetAsync(GetBaseUri());
if (response.IsSuccessStatusCode)
{
var jsonString = await response.Content.ReadAsStringAsync();
model = JsonConvert.DeserializeObject<T>(jsonString);
return model;
}
}
I'm trying to check Microsoft Linguistic Analysis API, basic example, so I have subscribed and addad my Key 1 in Ocp-Apim-Subscription-Key and Key 2 into the subscription key here client.DefaultRequestHeaders.Add("Ocp-Apim-Subscription-Key", "{subscription key}");.
Then I add Newtonsoft.Json with Manage NuGet Packages into the References of Application, even it is not listed in using of particular example using Newtonsoft.Json; using bNewtonsoft.Json.Serialization; not sure, I'm new with this tool.
I'm trying to check this example Linguistics API for C# to get some natural language processing results for text analysis mainly of Verb and Noun values according to this example results So I'm not sure if I'm on the right direction with this example, or possible I've missed something to install, maybe I need some additions. I found this Analyze Method not sure how and if I have to use it for this particular goal.
But seems like something is wrong with var queryString = HttpUtility.ParseQueryString(string.Empty); and HttpUtility does not exist.
using System;
using System.Net.Http.Headers;
using System.Text;
using System.Net.Http;
using System.Web;
namespace CSHttpClientSample
{
static class Program
{
static void Main()
{
MakeRequest();
Console.WriteLine("Hit ENTER to exit...");
Console.ReadLine();
}
static async void MakeRequest()
{
var client = new HttpClient();
var queryString = HttpUtility.ParseQueryString(string.Empty);
// Request headers
client.DefaultRequestHeaders.Add("Ocp-Apim-Subscription-Key", "{subscription key}");
var uri = "https://westus.api.cognitive.microsoft.com/linguistics/v1.0/analyze?" + queryString;
HttpResponseMessage response;
// Request body
byte[] byteData = Encoding.UTF8.GetBytes("{body}");
using (var content = new ByteArrayContent(byteData))
{
content.Headers.ContentType = new MediaTypeHeaderValue("< your content type, i.e. application/json >");
response = await client.PostAsync(uri, content);
}
}
}
}
You can create a new writeable instance of HttpValueCollection by calling System.Web.HttpUtility.ParseQueryString(string.Empty), and then use it as any NameValueCollection, like this:
NameValueCollection queryString = System.Web.HttpUtility.ParseQueryString(string.Empty);
Try adding a reference to System.Web, and possibly to System.Runtime.Serialization.
I am new in xamarin and visual studio,I have followed this tuto from microsoft:
enter link description here
to create a cross platform application,but I get this error:
'HttpWebRequest' does not contain a definition for 'GetResponseAsync' and no extension method 'GetResponseAsync' accepting a first argument of type 'HttpWebRequest' was found (a using directive or an assembly reference is it missing * ?)
and this is my code in which I get this error:DataService.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;
using System.IO;
using Newtonsoft.Json;
namespace shared
{
//This code shows one way to process JSON data from a service
public class DataService
{
public static async Task<dynamic> getDataFromService(string queryString)
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(queryString);
var response = await request.GetResponseAsync().ConfigureAwait(false);
var stream = response.GetResponseStream();
var streamReader = new StreamReader(stream);
string responseText = streamReader.ReadToEnd();
dynamic data = JsonConvert.DeserializeObject(responseText);
return data;
}
}
}
Please how can I solve it, I checked the HttpWebRequest documentation but I didn't get well the problem
thanks for help
Not sure about HttpWebRequest - but a newer and now recommended way to get data is the following:
public static async Task<dynamic> getDataFromService(string queryString)
{
using (var client = new HttpClient())
{
var responseText = await client.GetStringAsync(queryString);
dynamic data = JsonConvert.DeserializeObject(responseText);
return data;
}
}
Try that and let me know if it works.
I need to implement a webapi call into a legacy ASP.Net Web Forms application.
I know not all of the usings are need for this method but they are for other methods on the page i included on the off chance that one of them is causing the problem.
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using Newtonsoft.Json;
using System.Net.Http;
using System.Net.Http.Headers;
private string GetToken(string Username, string IpAddress)
{
string result = string.Empty;
HttpClient client = new HttpClient();
client.BaseAddress = new Uri(SSOApiUri);
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage response = client.GetAsync("api/yourcustomobjects").Result;
if (response.IsSuccessStatusCode)
{
***var data = await response.Content.ReadAsStringAsync();***
var token = JsonConvert.DeserializeObject<GetSSOTokenResponse>(data);
result = token.Token;
}
return result;
}
When I try to compile my application I get the following error at the emphisized line:
Error 19 The 'await' operator can only be used within an async method.
Consider marking this method with the 'async' modifier and changing
its return type to 'Task< string>'.
I am trying to implement a solution similar to the one found in this question but it is failing. I need to call the WebAPI Method, and return part of the result as a string... not a Task< String>
The error is straightforward. You must have an async method to use the await keyword. Your return value will automatically be wrapped in a Task as a result by the compiler. Note that the .Result can be changed to an await as well. Here's the Microsoft documentation on the async/await keywords
private async Task<string> GetToken(string Username, string IpAddress)
{
string result = string.Empty;
HttpClient client = new HttpClient();
client.BaseAddress = new Uri(SSOApiUri);
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage response = await client.GetAsync("api/yourcustomobjects");
if (response.IsSuccessStatusCode)
{
var data = await response.Content.ReadAsStringAsync();
var token = JsonConvert.DeserializeObject<GetSSOTokenResponse>(data);
result = token.Token;
}
return result;
}