Post parameter is always null

Question

Since upgrading to RC for WebAPI I m having some real odd issue when calling POST on my WebAPI  I ve even gone back to the basic version generated on new project  So   public void Post string value        and calling from Fiddler   Header  User-Agent  Fiddler Host  localhost 60725 Content-Type  application json Content-Length  29  Body         value    test      When I debug  the string  value  is never being assigned to  It s just always NULL  Anyone having this issue    I first saw the issue with a more complex type   The problem is not only bound to ASP NET MVC 4  the same problem occurs for a fresh ASP NET MVC 3 project after RC installation

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API    HttpPost  public bool UpdateTicketStatus Ticket t            string Id t Id      Model   public class Ticket       public int Id   get  set        public string AssignedTo   get  set        public string State   get  set        public string History   get  set        Using Post man tool send the content as json with raw data as below  It works         Id   169248        AssignedTo   xxxx        State   Committed        History   test1     Please make sure that you have enabled Cors     EnableCors origins       headers       methods            public class TicketController   ApiController

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Since you have only one parameter  you could try decorating it with the  FromBody  attribute  or change the method to accept a DTO with value as a property  as I suggested here  MVC4 RC WebApi parameter binding  UPDATE  The official ASP NET site was updated today with an excellent explanation  https   docs microsoft com en-us aspnet web-api overview advanced sending-html-form-data-part-1  In a nutshell  when sending a single simple type in the body  send just the value prefixed with an equal sign      e g  body    test

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I m a little late to the party  but anyone who stumbles across a NULL value passed when using a controller simply add     to the front of your POST request   The controller also passed a NULL value when I used the application json Content-Type  Note the  application x-www-form-urlencoded  Content-Type below  The return type from the API however is  application json     public static string HttpPostRequest string url  Dictionary lt string  string gt  postParameters                string postData                 foreach  string key in postParameters Keys                        postData    HttpUtility UrlEncode key                            HttpUtility UrlEncode postParameters key                             HttpWebRequest myHttpWebRequest    HttpWebRequest HttpWebRequest Create url           myHttpWebRequest Method    POST            byte   data   System Text Encoding ASCII GetBytes postData            myHttpWebRequest ContentType    application x-www-form-urlencoded           myHttpWebRequest ContentLength   data Length           Stream requestStream   myHttpWebRequest GetRequestStream            requestStream Write data  0  data Length           requestStream Close             HttpWebResponse myHttpWebResponse    HttpWebResponse myHttpWebRequest GetResponse             Stream responseStream   myHttpWebResponse GetResponseStream             StreamReader myStreamReader   new StreamReader responseStream  System Text Encoding Default            string pageContent   myStreamReader ReadToEnd             myStreamReader Close            responseStream Close             myHttpWebResponse Close             return pageContent

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I know this is not an answer to this question  but I came across it when searching for a solution to my problem   In my case  the complex type was not being bound but I was not doing a POST  I was doing a GET with querystring parameters  The solution was to add  FromUri  to the arg   public class MyController   ApiController       public IEnumerable lt MyModel gt  Get  FromUri  MyComplexType input                   input is not null as long as  FromUri  is present in the method arg

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The best solution for me is going full HTTP as below    Route  api open     HttpPost  public async Task lt string gt  open HttpRequestMessage request        var json   await request Content ReadAsStringAsync        JavaScriptSerializer jss   new JavaScriptSerializer                    WS OpenSession param   jss Deserialize lt WS OpenSession gt  json       return param sessionid      and then deserializing the string to the object you expect in the post body  For me  WS OpenSession is a class that contained sessionid  user and key   You can from there use the param object and access its properties   Very very effective   I did say sourced from this url   http   bizcoder com posting-raw-json-to-web-api

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For complex types  Web API tries to read the value from the message body  using a media-type formatter    Please check if you got any  Serializable  attribute decorating your model class   Remove the attribute to see if it works  This worked for me

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I was using Postman and I was doing the same mistake   passing the value as json object instead of string         value    test      Clearly the above one is wrong when the api parameter is of type string   So  just pass the string in double quotes in the api body    test

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If you have this character     in your json query in Postman  you should escape it if you need the character     in the json string value   Example          path    C   Users  Test  Documents  test txt

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JSON stringify      solved my issues

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I ve ran into this problem as well  and this is how I solved my problem  webapi code   public void Post  FromBody  dynamic data        string value   data value         do stuff        client code     post   webapi address     value   some value

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I am pretty late to this but was having similar issues and after a day of going through a lot of the answers here and getting background I have found the easiest lightweight solution to pass back one or more parameters to a Web API 2 Action is as follows   This assumes that you know how to setup a Web API controller action with correct routing  if not refer to  https   docs microsoft com en-us aspnet web-api overview getting-started-with-aspnet-web-api tutorial-your-first-web-api    First the Controller Action  this solution also requires the Newtonsoft Json library    HttpPost  public string PostProcessData  FromBody string parameters        if   String IsNullOrEmpty parameters             JObject json   JObject Parse parameters               Code logic below            Can access params via json  paramName   ToString              return         Client Side using jQuery  var dataToSend   JSON stringify   param1   value1   param2   value2          post   Web API URI         dataToSend    done function  data         console debug data      returned data from Web API        The key issue I found was making sure you only send a single overall parameter back to the Web API and make sure it has no name just the value       dataToSend  otherwise your value will be null on the server side   With this you can send one or many parameters to the Web API in a JSON structure and you don t need to declare any extra objects server side to handle complex data  The JObject also allows you to dynamically iterate over all parameters passed in allowing easier scalability should your parameters change over time  Hopefully that helps someone out that was struggling like me

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With Angular  I was able to pass data in this format    data        JSON stringify   u   scope usrname1  p   scope pwd1      headers     Content-Type    application x-www-form-urlencoded  charset utf-8      And in Web API Controler        HttpPost      public Hashtable Post  FromBody string jsonString                IDictionary lt string  string gt  data   JsonConvert DeserializeObject lt IDictionary lt string  string gt  gt  jsonString           string username   data  u            string pwd   data  p                Alternatively  I could also post JSON data like this       data    PaintingId  1  Title   Animal show   Price  10 50      And  in the controller  accept a class type like this         HttpPost      public string POST Models PostModel pm                           Either way works  if you have an established public class in the API then post JSON  otherwise post       JSON stringify

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Adding line          ValueProviderFactories Factories Add new JsonValueProviderFactory       to the end of function protected void Application Start   in Global asax cs fixed similar problem for me in ASP NET MVC3

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Hope this helps   Looking in different comments and other forums  I mix some snippets and For me  this code works         In the Controller  public HttpResponseMessage Post  FromBody  string jsonData                HttpResponseMessage response   Request CreateResponse HttpStatusCode OK  jsonData                        try                        string jsonString   jsonData ToString                JArray jsonVal   JArray Parse jsonString  as JArray              dynamic mylist  jsonVal              foreach  dynamic myitem in mylist                                string strClave string Empty                  string strNum string Empty                  string strStatus string Empty                   strClave   myitem clave                  strNum myitem num                  strStatus   myitem status                       in the WebApiConfig cs include this line for avoid the null value in the  FromBody  variable var jsonFormatter   config Formatters OfType   First     public static void Register HttpConfiguration config                     config Routes MapHttpRoute                              name   DefaultApi                               routeTemplate   api  controller   id                                defaults  new   id   RouteParameter Optional                                          var jsonFormatter   config Formatters OfType lt JsonMediaTypeFormatter gt    First       this line makes no more null when use  FromBody             in the client side   the mos important is concatenate the equal sign before the serialized data    string json         SerialData      for seralize I m using    System Web Script Serialization JavaScriptSerializer serializer   new  System Web Script Serialization JavaScriptSerializer             List lt Dictionary lt string  object gt  gt  rows   new List lt Dictionary lt string  object gt  gt             Dictionary lt string  object gt  row          foreach  DataRow dr in DsCnx Tables 0  Rows                        row   new Dictionary lt string  object gt                 foreach  DataColumn col in DsCnx Tables 0  Columns                                row Add col ColumnName  dr col                              rows Add row                     SerialData  serializer Serialize rows          PostRequest  http   localhost 53922 api Demo   SerialData     this is my PostRequest function  here the Content Type thet I use is httpWebRequest ContentType    application x-www-form-urlencoded  charset utf-8     private static string PostRequest string url  string SerialData                         string result   String Empty          HttpWebRequest httpWebRequest    HttpWebRequest WebRequest Create url           httpWebRequest ContentType    application x-www-form-urlencoded  charset utf-8           httpWebRequest Method    POST            using  var streamWriter   new StreamWriter httpWebRequest GetRequestStream                           string json         SerialData                streamWriter Write json               streamWriter Flush                streamWriter Close                      try                       using  var response   httpWebRequest GetResponse   as HttpWebResponse                                if  httpWebRequest HaveResponse  amp  amp  response    null                                        using  var reader   new StreamReader response GetResponseStream                                                   result   reader ReadToEnd                                                                            catch  WebException e                        if  e Response    null                                using  var errorResponse    HttpWebResponse e Response                                        using  var reader   new StreamReader errorResponse GetResponseStream                                                   string error   reader ReadToEnd                            result   error                                                                            return result ToString             here is the links where i found one code example for reference    https   weblog west-wind com posts 2012 Aug 30 Using-JSONNET-for-dynamic-JSON-parsing jobject-and-jarray-in-aspnet-web-api  https   blog codenamed nl 2015 05 12 why-your-frombody-parameter-is-always-null

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For those who are having the same issue with Swagger or Postman like I did  if you are passing a simple attribute as string in a post  even with the  ContentType  specified  you still going to get a null value   Passing just   MyValue  Will get in the controller as null   But if you pass    MyValue   The value will get right   The quotes made the difference here  Of course  this is only for Swagger and Postman  For instance  in a Frontend app using Angular this should be resolved by the framework automaticly

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I ve just had this occur using Fiddler  The problem was that I hadn t specified Content-Type   Try including a header for Content-Type in your POST request   Content-Type  application x-www-form-urlencoded     Alternatively  as per comments below  you may need to include a JSON header  Content-Type  application json

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If you are sure about your sent JSON then you must trace your API carefully    Install Microsoft AspNet WebApi Tracing package Add config EnableSystemDiagnosticsTracing    in the WebApiConfig class inside Register method    Now look at the Debug output and you will probably find an invalid ModelState log entry   If ModelState is invalid you may find the real cause in its Errors   No one can even guess such an exception   Could not load file or assembly  Newtonsoft Json  Version 9 0 0 0  Culture neutral  PublicKeyToken 30ad4fe6b2a6aeed  or one of its dependencies  The located assembly s manifest definition does not match the assembly reference   Exception from HRESULT  0x80131040

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If you put  FromBody  annotation and you have a Dto object as a parameter to your method and still not able to get the data through  start looking into the properties and fields of your DTO    I had this same problem  where my DTO was coming null  I found the reason was that one of the properties was pointing into an object that cannot be serialised    which causes the media-formatter to fail to parse the data  Thus the object was always null   Hope it helps others too

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Correct passing single parameter in body to WebAPI  works this code   post url        productId    And catching it in action  HttpPost  public ShoppingCartAddRemoveViewModel Delete  FromBody string value   Key is to use magic word  value   It may be also int  or some primitive type  No matter content-type or header corrections Mess is that this code doesn t work in mvc post action

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I know the OP was originally sending a single string  but for future reference  it is also worth noting that malformed JSON will also arrive as null into the post method  In my case  a missing comma between two properties caused what was otherwise fine  to break

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Met with a similar problem in ASP NET Core and another possible cause is ASP NET binding  silent  failure due to various reasons such as sending null to be bound to a not null property          prop1  1139357       prop2  1139356        items              key   15   someprop  34  notnullprop  null             key   16   someprop  34  notnullprop  null             key   22   someprop  34  notnullprop  null       On such case there is no exception being thrown and the whole model will be null  even if this happens deep inside the object hierarchy

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I have been scratching my head over this today    My solution is to change the  FromBody  to a HttpRequestMessage  essentially moving up the HTTP stack   In my case I am sending data across the wire which is zipped json which is then base64 d   All this from an android app     The original signature of my web endpoint looked like this  using  FromBody        My fix for this issue was to revert to using a HttpRequestMessage for the signature of my endpoint      You can then get access to the post data using this line of code     This works and allows you access to the raw untouched post data   You don t have to mess around with fiddler putting an   sign at the beginning of your string or changing the content-type   As an aside  I first tried to following one of the answers above which was to change the content type to   Content-Type  application x-www-form-urlencoded    For raw data this is bad advice because it strips out   characters   So a base64 string that starts like this   MQ0AAB LCAAAAAA  ends up like this  MQ0AAB LCAAAAAA   Not what you want   Another benefit of using HttpRequestMessage is that you get access to all the http headers from within your endpoint

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I had the same issue and found that when changing the Content Type to  application json  did not fix the problem  However  application json  charset utf-8  worked

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After some tries  I think the default behavior is correct and there is nothing to hack   The only trick is  if your post method argument is string like below  you should send a plain string with double quotes in the body  when using ajax or postman   e g      send     a   1   in body to me  note the outer double quotes  HttpPost  api1    public String PostMethod1  FromBody string value        return  received     value       received    a   1       Otherwise if you send a json string in the post body without outer double quotes and escaped inner quotes  then it should be able to be parsed to the model class  the argument type   e g     a  1   b  2   public class MyPoco      public int a      public int b       send   a  1   b  2  in body to me  HttpPost  api2    public String PostMethod2  FromBody MyPoco value        return  received     value ToString        received your namespace MyPoco

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If you are using a DataContractSerializer for your Xml Formatter or JSON Formatter  you need to get rid of it  I had this in my WebApiConfig file    public static void Register HttpConfiguration config         config Routes MapHttpRoute             name   DefaultApi              routeTemplate   api  controller   id               defaults  new   id   RouteParameter Optional                     var jsonFormatter   config Formatters OfType lt JsonMediaTypeFormatter gt    First         jsonFormatter UseDataContractJsonSerializer   true      Simply I comment out jsonFormatter UseDataContractJsonSerializer   true and my input parameter isn t null anymore  Thanks to  Despertar  for giving me a clue

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I had the same problem in Fiddler  I already had Content-Type  application json  charset utf-8 or Content-Type  application json in the request header   My request body was also a plain string  and in Fiddler I had written    controller   ctrl    This made the string parameter in my POST method be null   Fix  remember to use quotation marks  thereby indicating a string  That is  I fixed it by writing    controller   ctrl      Note  when writing JSON  either be sure to use apostrophes or escape the quotation marks like this      controller     ctrl

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it doesn t matter what type of value you wish to post  just enclose it within the quotation marks  to get it as string  Not for complex types   javascript       var myData   null  url    api      Named      NamedMethod        myData   7        http post url        myData                  then function  response    console log response data            myData    some sentence         http post url        myData                  then function  response    console log response data            myData     name   person name   age  21          http post url        JSON stringify myData                   then function  response    console log response data             http post url        angular toJson myData                   then function  response    console log response data         c        public class NamedController   ApiController                HttpPost          public int NamedMethod  FromBody  string value                        return value    null   1   0

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This link helped me  http   encosia com using-jquery-to-post-frombody-parameters-to-web-api   Basically it says that you should use an empty name for the parameter   public string Post  FromBody string myParameter               post   api dosomething           myvalue

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I had the same issue of getting null as parameter  but it was related to large objects  It turned out the problem was related to IIS max length  It can be configured in web config      lt system web gt       lt httpRuntime targetFramework  4 7  maxRequestLength  1073741824    gt     lt  system web gt    I wonder why Web API suppressed the error and sends null objects to my APIs  I found the error using Microsoft AspNet WebApi Tracing

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Try creating a class to serve as the data model  then send a JSON object with properties matching the properties of your data model class   Note  I have tested this and it works with the newest MVC 4 RC 2012 that I just downloaded today    public HttpResponseMessage Post ValueModel model        return Request CreateResponse lt string gt  HttpStatusCode OK   Value Recieved      model Value      public class ValueModel       public string Value   get  set        The below JSON object is sent in HTTP-POST body  content-type is application json     value    In MVC4 Beta you could map to simple types like string  but testing with RC 2012 I have only been able to map to DataModels and only JSON  application json  and url-encoded  application x-www-form-urlencoded body formats have worked  XML is not working for some reason      I believe the reason why you have to create a data model class is because simple values are assumed to be from the url parameters  and a single complex value is assumed to be from the body  They do have the  FromBody  and  FromUrl  attributes  but using  FromBody  string value still did not work for me  Seems like they are still working out a lot of bugs so I m sure this will change in the future   Edit  Got XML to work in the body  The default XML serializer was changed to DataContractSerializer instead of XmlSerializer  Putting the following line in my Global asax file fixed this issue  reference   GlobalConfiguration Configuration Formatters XmlFormatter UseXmlSerializer   true

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I tried many of the answers in this thread and none of them worked for me  Then I came across this answer to a similar post  https   stackoverflow com a 40853424 2120023 where he mentions HttpContext Request Body so another search and I found this https   stackoverflow com a 1302851 2120023 which gave me HttpContext Current so I finally got this to work using   HttpContext Current Request Form Get  value      My request from Postman   curl --location --request POST  https   example com token  --header  Content-Type  application x-www-form-urlencoded  --data-urlencode  value test

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I had a similar issue where the request object for my Web API method was always null  I noticed that since the controller action name was prefixed with  Get   Web API treated this as a HTTP GET rather than a POST  After renaming the controller action  it now works as intended

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The most simple way I found to deal with simple JSON object that I pass into MVC 6 is getting the the type of the post parameter like NewtonSoft jObject   public ActionResult Test2  FromBody  jObject str            return Json new   message    Test1 Returned     str

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The issue is that your action method is expecting a simple type i e   a string parameter value  What you are providing is an object    There are 2 solutions to your problem    Create a simple class with  value  property and then use that class as parameter  in which case Web API model binding will read JSON object from request and bind it to your param object  values  property  Just pass string value  test   and it will work

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This worked for me    Create a C  DTO class  with a property for every attribute you want to pass from jQuery Ajax  public class EntityData       public string Attr1   get  set        public string Attr2   get  set       Define the web api method    HttpPost    public JObject AddNewEntity  FromBody  EntityData entityData     Call the web api as such   var entityData          attr1    value1        attr2    value2        ajax       type   POST       url    api YOURCONTROLLER addnewentity       async  true      cache  false      data  JSON stringify entityData       contentType   application json  charset utf-8       dataType   json       success  function  response

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In my case decorating the parameter class with the  JsonObject MemberSerialization OptOut   attribute from Newtonsoft did the trick    For example    HttpPost   Route  MyRoute    public IHttpActionResult DoWork MyClass args               JsonObject MemberSerialization OptOut   public Class MyClass

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In my case the problem was that the parameter was a string and not an object  i changed the parameter to be JObject of Newsoft Json and it works

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Double check your data types  The dotnet model binder will not convert a float to an integer  and I m assuming other related concepts   This will cause the entire model to be rejected    If you have json like this          shoeSize   10 5     but your c  model looks like this   class Shoe      public int shoeSize      the model binder will reject the model and you will get null

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I was looking for a solution to this problem for some minutes now  so I ll share my solution    If you post a model your model needs to have an empty default constructor  otherwise the model can t be created  obviously  Be careful while refactoring

[c#] Post parameter is always null

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