POST string to ASP NET Web Api application - returns null

Question

Im trying to transmit a string from client to ASP NET MVC4 application   But I can not receive the string  either it is null or the post method can not be found  404 error   Client Code to transmit the string  Console Application    HttpWebRequest request    HttpWebRequest WebRequest Create  http   localhost 49032 api test    request Credentials   new NetworkCredential  user    pw    request Method    POST   string postData    Short test      byte   byteArray   Encoding UTF8 GetBytes postData   request ContentType    application x-www-form-urlencoded   request ContentLength   byteArray Length   Stream dataStream   request GetRequestStream    dataStream Write byteArray  0  byteArray Length   dataStream Close     WebResponse response   request GetResponse    Console WriteLine   HttpWebResponse response  StatusDescription   dataStream   response GetResponseStream     StreamReader reader   new StreamReader dataStream   string responseFromServer   reader ReadToEnd    Console WriteLine responseFromServer   reader Close    dataStream Close    response Close    Console ReadLine      ASP NET Web Api Controller   public class TestController   ApiController        Authorize      public String Post byte   value                return value Length ToString              In that case I m able to call the  Post  method  but  value  is NULL  If I change the method signature to  string value  than it will never called   Even  without  the  Authorize  setting it has the same strange behavior  -  So it has nothing to do with the user authentication   Any ideas what I m doing wrong  I m grateful for any help

User · Answer

Darrel is of course right on with his response. One thing to add is that the reason why attempting to bind to a body containing a single token like "hello".

is that it isn’t quite URL form encoded data. By adding “=” in front like this:

=hello

it becomes a URL form encoding of a single key value pair with an empty name and value of “hello”.

However, a better solution is to use application/json when uploading a string:

POST /api/sample HTTP/1.1
Content-Type: application/json; charset=utf-8
Host: host:8080
Content-Length: 7

"Hello"

Using HttpClient you can do it as follows:

HttpClient client = new HttpClient();
HttpResponseMessage response = await client.PostAsJsonAsync(_baseAddress + "api/json", "Hello");
string result = await response.Content.ReadAsStringAsync();
Console.WriteLine(result);

Henrik

User · Answer

FromBody  IDictionary lt string object gt  data

User · Answer

You seem to have used some  Authorize  attribute on your Web API controller action and I don t see how this is relevant to your question   So  let s get into practice  Here s a how a trivial Web API controller might look like   public class TestController   ApiController       public string Post  FromBody  string value                return value            and a consumer for that matter   class Program       static void Main                 using  var client   new WebClient                          client Headers HttpRequestHeader ContentType     application x-www-form-urlencoded               var data     Short test                  var result   client UploadString  http   localhost 52996 api test    POST   data               Console WriteLine result                       You will undoubtedly notice the  FromBody  decoration of the Web API controller attribute as well as the   prefix of the POST data om the client side  I would recommend you reading about how does the Web API does parameter binding to better understand the concepts   As far as the  Authorize  attribute is concerned  this could be used to protect some actions on your server from being accessible only to authenticated users  Actually it is pretty unclear what you are trying to achieve here You should have made this more clear in your question by the way  Are you are trying to understand how parameter bind works in ASP NET Web API  please read the article I ve linked to if this is your goal  or are attempting to do some authentication and or authorization  If the second is your case you might find the following post that I wrote on this topic interesting to get you started   And if after reading the materials I ve linked to  you are like me and say to yourself  WTF man  all I need to do is POST a string to a server side endpoint and I need to do all of this  No way  Then checkout ServiceStack  You will have a good base for comparison with Web API   I don t know what the dudes at Microsoft were thinking about when designing the Web API  but come on  seriously  we should have separate base controllers for our HTML  think Razor  and REST stuff  This cannot be serious

User · Answer

i meet this problem  and find this article  http   www jasonwatmore com post 2014 04 18 Post-a-simple-string-value-from-AngularJS-to-NET-Web-API aspx     The solution  I found was to simply wrap the string value in double   quotes in your js post   works like a charm  FYI

User · Answer

For WebAPI  here is the code to retrieve body text without going through their special  FromBody  binding   public class YourController   ApiController        HttpPost      public HttpResponseMessage Post                 string bodyText   this Request Content ReadAsStringAsync   Result            more code here

User · Answer

Web API works very nicely if you accept the fact that you are using HTTP   It s when you start trying to pretend that you are sending objects over the wire that it starts to get messy    public class TextController   ApiController               public HttpResponseMessage Post HttpRequestMessage request                 var someText   request Content ReadAsStringAsync   Result              return new HttpResponseMessage    Content   new StringContent someText                        This controller will handle a HTTP request  read a string out of the payload and return that string back   You can use HttpClient to call it by passing an instance of StringContent   StringContent will be default use text plain as the media type   Which is exactly what you are trying to pass        Fact      public void PostAString                  var client   new HttpClient             var content   new StringContent  Some text            var response   client PostAsync  http   oak 9999 api text   content  Result           Assert Equal  Some text  response Content ReadAsStringAsync   Result

User · Answer

I use this code to post HttpRequests        lt summary gt              Post this message               lt  summary gt               lt param name  url  gt URL of the document  lt  param gt               lt param name  bytes  gt The bytes  lt  param gt          public T Post lt T gt  string url  byte   bytes                T item          var request   WritePost url  bytes            using  var response   request GetResponse   as HttpWebResponse                        item   DeserializeResponse lt T gt  response               response Close                       return item                  lt summary gt          Writes the post           lt  summary gt           lt param name  url  gt The URL  lt  param gt           lt param name  bytes  gt The bytes  lt  param gt           lt returns gt  lt  returns gt      private static HttpWebRequest WritePost string url  byte   bytes                ServicePointManager ServerCertificateValidationCallback    sender  certificate  chain  errors    gt  true           HttpWebRequest request    HttpWebRequest  WebRequest Create url           Stream stream   null          try                       request Headers Clear                request PreAuthenticate   true              request Connection   null              request Expect   null              request KeepAlive   false              request ContentLength   bytes Length              request Timeout   -1              request Method    POST               stream   request GetRequestStream                stream Write bytes  0  bytes Length                     catch  Exception e                        GetErrorResponse url  e                     finally                       if  stream    null                                stream Flush                    stream Close                                    return request          In regards to your code  try it without the content Type  request ContentType    application x-www-form-urlencoded     update  I believe the problem lies with how you are trying to retrieve the value  When you do a POST and send bytes via the Stream  they will not be passed into the action as a parameter  You ll need to retrieve the bytes via the stream on the server   On the server  try getting the bytes from stream  The following code is what I use             lt summary gt  Gets the body   lt  summary gt            lt returns gt  The body   lt  returns gt       protected byte   GetBytes                 byte   bytes          using  var binaryReader   new BinaryReader Request InputStream                         bytes   binaryReader ReadBytes Request ContentLength                       return bytes

[c#] POST string to ASP.NET Web Api application - returns null

Examples related to c#

Examples related to asp.net

Examples related to asp.net-mvc

Examples related to post

Examples related to asp.net-web-api