I made a console app to consume a Web API I just made. The console app code does not compile. It gives me the compilation error:
'System.Net.Http.HttpContent' does not contain a definition for
'ReadAsAsync' and no extension method 'ReadAsAsync' accepting a
first argument of type 'System.Net.Http.HttpContent' could be
found (are you missing a using directive or an assembly reference?)
Here's a test method in which this error occurs.
static IEnumerable<Foo> GetAllFoos()
{
using (HttpClient client = new HttpClient())
{
client.DefaultRequestHeaders.Add("appkey", "myapp_key");
var response = client.GetAsync("http://localhost:57163/api/foo").Result;
if (response.IsSuccessStatusCode)
return response.Content.ReadAsAsync<IEnumerable<Foo>>().Result.ToList();
}
return null;
}
I have used this method and consumed it from an MVC client.
This question is related to
asp.net
.net
asp.net-mvc
asp.net-web-api
Make sure that you have installed the correct NuGet package
in your console application:
<package id="Microsoft.AspNet.WebApi.Client" version="4.0.20710.0" />
and that you are targeting at least .NET 4.0.
This being said, your GetAllFoos
function is defined to return an IEnumerable<Prospect>
whereas in your ReadAsAsync
method you are passing IEnumerable<Foo>
which obviously are not compatible types.
Install-Package Microsoft.AspNet.WebApi.Client
Adding a reference to System.Net.Http.Formatting.dll may cause DLL mismatch issues. Right now, System.Net.Http.Formatting.dll appears to reference version 4.5.0.0 of Newtonsoft.Json.DLL, whereas the latest version is 6.0.0.0. That means you'll need to also add a binding redirect to avoid a .NET Assembly exception if you reference the latest Newtonsoft NuGet package or DLL:
<dependentAssembly>
<assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-6.0.0.0" newVersion="6.0.0.0" />
</dependentAssembly>
So an alternative solution to adding a reference to System.Net.Http.Formatting.dll is to read the response as a string and then desearalize yourself with JsonConvert.DeserializeObject(responseAsString). The full method would be:
public async Task<T> GetHttpResponseContentAsType(string baseUrl, string subUrl)
{
using (var client = new HttpClient())
{
client.BaseAddress = new Uri(baseUrl);
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage response = await client.GetAsync(subUrl);
response.EnsureSuccessStatusCode();
var responseAsString = await response.Content.ReadAsStringAsync();
var responseAsConcreteType = JsonConvert.DeserializeObject<T>(responseAsString);
return responseAsConcreteType;
}
}
try this
Package manager console
Install-Package System.Net.Http.Formatting.Extension -Version 5.2.3
and then add by using add reference .
USE This Assembly Referance in your Project
Add a reference to System.Net.Http.Formatting.dll
or if you have VS 2012 you can goto the package manager console and type Install-Package Microsoft.AspNet.WebApi.Client
This would download the latest version of the package
Source: Stackoverflow.com