How to receive JSON as an MVC 5 action method parameter

Question

I have been trying the whole afternoon crawling through the web trying to receive a JSON object in the action controller   What is the correct and or easier way to go about doing it   I have tried the following  1     Post  Roles AddUser  HttpPost  public ActionResult AddUser String model        if model    null                return Json  Success         else               return Json  An Error Has occoured               Which gave me a null value on my input   2     Post  Roles AddUser  HttpPost  public ActionResult AddUser IDictionary lt string  object gt  model        if model    null                return Json  Success         else               return Json  An Error Has occoured               which gives me a 500 error on the jquery side which is trying to post to it   meaning that it didn t bind correctly    here is my jQuery code    lt script gt  function submitForm          var usersRoles   new Array      jQuery   dualSelectRoles2 option   each function              usersRoles push jQuery this  val                 console log usersRoles        jQuery ajax           type   POST           url    Url Action  AddUser             contentType   application json  charset utf-8           dataType   json           data  JSON stringify usersRoles           success  function  data    alert data              failure  function  errMsg                alert errMsg                           All I want to do is receive my JSON object in my mvc action

User · Answer

There are a couple issues here  First  you need to make sure to bind your JSON object back to the model in the controller  This is done by changing  data  JSON stringify usersRoles     to   data    model  JSON stringify usersRoles       Secondly  you aren t binding types correctly with your jquery call  If you remove   contentType   application json  charset utf-8     it will inherently bind back to a string   All together  use the first ActionResult method and the following jquery ajax call       jQuery ajax           type   POST           url    Url Action  AddUser             dataType   json           data    model  JSON stringify usersRoles             success  function  data    alert data              failure  function  errMsg            alert errMsg

User · Answer

Unfortunately  Dictionary has problems with Model Binding in MVC  Read the full story here  Instead  create a custom model binder to get the Dictionary as a parameter for the controller action   To solve your requirement  here is the working solution -   First create your ViewModels in following way  PersonModel can have list of RoleModels   public class PersonModel       public List lt RoleModel gt  Roles   get  set        public string Name   get  set       public class RoleModel       public string RoleName   get  set       public string Description   get  set       Then have a index action which will be serving basic index view -   public ActionResult Index         return View        Index view will be having following JQuery AJAX POST operation -    lt script src    Scripts jquery-1 10 2 min js  gt  lt  script gt   lt script gt        function                  click1   click function  e                 var jsonObject                      Name     Rami                    Roles       RoleName    Admin    Description     Admin Role       RoleName    User    Description     User Role                                  ajax                   url    Url Action  AddUser                     type   POST                   data  JSON stringify jsonObject                   contentType   application json  charset utf-8                   dataType   json                   error  function  response                        alert response responseText                                  success  function  response                        alert response                                                           lt  script gt    lt input type  button  value  click1  id  click1    gt    Index action posts to AddUser action -    HttpPost  public ActionResult AddUser PersonModel model        if  model    null                return Json  Success              else               return Json  An Error Has occoured              So now when the post happens you can get all the posted data in the model parameter of action   Update   For asp net core  to get JSON data as your action parameter you should add the  FromBody  attribute before your param name in your controller action  Note  if you re using ASP NET Core 2 1  you can also use the  ApiController  attribute to automatically infer the  FromBody  binding source for your complex action method parameters   Doc

User · Answer

You are sending a array of string  var usersRoles       jQuery   dualSelectRoles2 option   each function          usersRoles push jQuery this  val              So change model type accordingly   public ActionResult AddUser List lt string gt  model

User · Answer

fwiw  this didn t work for me until I had this in the ajax call   contentType   application json  charset utf-8     using Asp Net MVC 4

[asp.net] How to receive JSON as an MVC 5 action method parameter

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