System Net Http HttpContent does not contain a definition for ReadAsAsync and no extension method

Question

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 lt Foo gt  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 lt IEnumerable lt Foo gt  gt    Result ToList           return null      I have used this method and consumed it from an MVC client

User · Answer

USE This Assembly Referance in your Project  Add a reference to System Net Http Formatting dll

User · Answer

After a long struggle  I found the solution   Solution  Add a reference to System Net Http Formatting dll  This assembly is also available in the C  Program Files Microsoft ASP NET ASP NET MVC 4 Assemblies folder   The method ReadAsAsync is an extension method declared in the class HttpContentExtensions  which is in the namespace System Net Http in the library System Net Http Formatting   Reflector came to rescue

User · Answer

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

User · Answer

if you unable to find assembly reference from when  Right click on reference - add required assembly    try this Package manager console Install-Package System Net Http Formatting Extension -Version 5 2 3 and then add  by using  add  reference

User · Answer

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     lt dependentAssembly gt      lt assemblyIdentity name  Newtonsoft Json  publicKeyToken  30ad4fe6b2a6aeed  culture  neutral    gt       lt bindingRedirect oldVersion  0 0 0 0-6 0 0 0  newVersion  6 0 0 0    gt    lt  dependentAssembly gt     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 lt T gt  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 lt T gt  responseAsString            return responseAsConcreteType

User · Answer

Make sure that you have installed the correct NuGet package in your console application    lt package id  Microsoft AspNet WebApi Client  version  4 0 20710 0    gt    and that you are targeting at least  NET 4 0   This being said  your GetAllFoos function is defined to return an IEnumerable lt Prospect gt  whereas in your ReadAsAsync method you are passing IEnumerable lt Foo gt  which obviously are not compatible types   Install-Package Microsoft AspNet WebApi Client

[asp.net] 'System.Net.Http.HttpContent' does not contain a definition for 'ReadAsAsync' and no extension method

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