c# - Unable to pass model from View to controler using ajax -

first of can search , found questions this: (passing model view controller using jquery ajax

but when i'm trying make in marker answer receive error circular reference i'm asking in sending model view controler: here view:

@model magazyn.models.deviceusage  @{     viewbag.title = "return";     //layout = "~/views/shared/_layout.cshtml";     var val = json.encode(model); }  <h2>return</h2> <script>     $(document).ready(function () {         $('.z').on('click', function (event) {             event.preventdefault();             var check=@html.raw(model)             $.ajax({                 url: "/deviceusage/return",                 type: "post",                 contenttype: "application/json; charset=utf-8",                 datatype: 'html',                 data: '{dev:' + json.stringify(check) + '}',                 error: function (data) {                     alert("wystąpił nieokreślony błąd " + data);                 },                 success: function (data) {                     $('.modal-body').html(data);                 }             })         })     }); </script>  @using (html.beginform()) {     @html.antiforgerytoken()  <div class="form-horizontal">     <h4>deviceusage</h4>     <hr />     @html.validationsummary(true)     <div class="input-group">         <div class="input-group-addon">             @html.labelfor(model => model.storageid, "gdzie oddałeś?", new { @class = "control-label col-md-2" })         </div>         <div class="">             @html.dropdownlist("storageid", null, new {@class="form-control" })             @html.validationmessagefor(model => model.storageid)         </div>     </div>       @html.hiddenfor(model => model.deviceinstanceid)      <div class="input-group" style="padding-top:5px">                    <input type="submit" value="save" class="btn btn-default z" />     </div> </div> } 

and controller:

[httppost]     [validateantiforgerytoken]     public actionresult return(deviceusage dev)     {         if(dev.storageid==3)         {             modelstate.addmodelerror("", "nie można oddać na własne biurko");             viewbag.storageid = new selectlist(unitofwork.storagerepository.get(), "id", "name", dev.storageid);             return partialview(dev);         }         dev.userid = 1;         unitofwork.deviceusagerepository.update(dev);         unitofwork.save();         return redirecttoaction("mydevices");     } 

i'm asking suggestions, code snippets me in solving problem.

@update

with uncommented var val= json.encode(model); error:

a circular reference detected while serializing object of type 'system.data.entity.dynamicproxies.deviceinstance_445e26162dd165393d1cb531a60ba066c466c22965b1714e8f224391398180ca'. 

with commented uncaught referenceerror: system not defined above error thrown when trying stringify

i doubt on following line of code:

var check=@html.raw(model) data: '{dev:' + json.stringify(check) + '}' 

can try below code?

    $.ajax({         url: "/deviceusage/return",         type: "post",         contenttype: "application/json; charset=utf-8",         data: json.stringify({ dev:            deviceinstanceid: $('#deviceinstanceid').val(),            userid: "1",            storageid: $('#storageid').val()         }),         error: function (data) {             alert("wystąpił nieokreślony błąd " + data);         },         success: function (data) {             $('.modal-body').html(data);         }     });