json parsing error syntax error unexpected end of input

Question

I got the following piece of code  function pushJsonData productName          ajax           url    knockout SaveProduct           type   POST           contentType   application json           dataType   json           data        Name       AA                async  false          success  function                  loadJsonData                          error  function  jqXHR  textStatus  errorThrown              alert textStatus     in pushJsonData      errorThrown         jqXHR                         Notice that I hard coded the data value  The data get pushed into the database fine  However  I keep getting the error  parsing error syntax error unexpected end of input   I am sure my data is in correct JSON syntax  When I checked with on Network of Chrome inspector the saveProduct request showed the data is correct       Name    AA      This POST request did not have response  So I am clueless as to where the parse error was coming from  I tried using FireFox browser  the same thing happened   Can anyone give some idea as to what is wrong   Thanks    P S  Here is the controller code  namespace MvcApplJSON Controllers       public class KnockoutController   Controller                             GET   Knockout           public ActionResult Index                         return View                        HttpGet          public JsonResult GetProductList                         var model   new List lt Product gt                 try                               using  var db   new KOEntities                                          var product   from p in db Products orderby p Name select p                      model   product ToList                                                catch  Exception ex                throw ex                return Json model  JsonRequestBehavior AllowGet                      HttpPost          public void SaveProduct  Product product                        using  var db   new KOEntities                                  db Products Add new Product   Name   product Name  DateCreated   DateTime Now                     db SaveChanges

User · Answer

I did this in Node JS and it solved this problem   var data   JSON parse Buffer concat arr  toString

User · Answer

Unexpected end of input means that the parser has ended prematurely  For example  it might be expecting  abcd   wxyz  but only sees  abcd   wxy    This can be a typo error somewhere  or it could be a problem you get when encodings are mixed across different parts of the application   One example  consider you are receiving data from a native app using chrome runtime sendNativeMessage   chrome runtime sendNativeMessage  appname    toJSON     gt  return msg     data   gt       console log data         Now before your callback is called  the browser would attempt to parse the message using JSON parse which can give you  unexpected end of input  errors if the supplied byte length does not match the data

User · Answer

May be it will be useful   The method parameter name should be the same like it has JSON  It will work fine  C   public ActionResult GetMTypes int id    JS   var params     id  modelId                      var url     Url Action  GetMTypes    MaintenanceTypes                        ajax                        type   POST                        url  url                       contentType   application json  charset utf-8                        dataType   json                        data  JSON stringify params     It will NOT work fine  C   public ActionResult GetMTypes int modelId    JS   var params     id  modelId                      var url     Url Action  GetMTypes    MaintenanceTypes                        ajax                        type   POST                        url  url                       contentType   application json  charset utf-8                        dataType   json                        data  JSON stringify params

User · Answer

I was using a Node http request and listening for the data event   This event only puts the data into a buffer temporarily  and so a complete JSON is not available   To fix  each data event must be appended to a variable  Might help someone  http   nodejs org api http html

User · Answer

I ve had the same error parsing a string containing  n into JSON  The solution was to use string replace   n     n

User · Answer

This error occurs on an empty JSON file reading  To avoid this error in NodeJS I m checking the file s size  const   size     fs statSync JSON FILE   const content   size   JSON parse fs readFileSync JSON FILE     DEFAULT VALUE

User · Answer

I can t say for sure what the problem is  Could be some bad character  could be the spaces you have left at the beginning and at the end  no idea   Anyway  you shouldn t hardcode your JSON as strings as you have done  Instead the proper way to send JSON data to the server is to use a JSON serializer   data  JSON stringify   name    AA        Now on the server also make sure that you have the proper view model expecting to receive this input   public class UserViewModel       public string Name   get  set        and the corresponding action    HttpPost  public ActionResult SaveProduct UserViewModel model                Now there s one more thing  You have specified dataType   json   This means that you expect that the server will return a JSON result  The controller action must return JSON  If your controller action returns a view this could explain the error you are getting  It s when jQuery attempts to parse the response from the server    HttpPost  public ActionResult SaveProduct UserViewModel model                return Json new   Foo    bar          This being said  in most cases  usually you don t need to set the dataType property when making AJAX request to an ASP NET MVC controller action  The reason for this is because when you return some specific ActionResult  such as a ViewResult or a JsonResult   the framework will automatically set the correct Content-Type response HTTP header  jQuery will then use this header to parse the response and feed it as parameter to the success callback already parsed   I suspect that the problem you are having here is that your server didn t return valid JSON  It either returned some ViewResult or a PartialViewResult  or you tried to manually craft some broken JSON in your controller action  which obviously you should never be doing but using the JsonResult instead    One more thing that I just noticed   async  false    Please  avoid setting this attribute to false  If you set this attribute to false you are are freezing the client browser during the entire execution of the request  You could just make a normal request in this case  If you want to use AJAX  start thinking in terms of asynchronous events and callbacks

User · Answer

For me the issue was due to single quotes for the name value pair     data     Name   AA     Once I changed it to double quotes for the name value pair it works fine    data     Name   AA    or like this    data      Name     AA

User · Answer

spoiler  possible Server Side Problem   Here is what i ve found  my code expected the responce from my server  when the server returned just 200 code  it wasnt enough herefrom json parser thrown the error error unexpected end of input  fetch url            method   POST           body  JSON stringify json           headers               Content-Type    application json                              then res   gt  res json       here is my code waites the responce from the server          then  res    gt              toastr success  Created Type is sent successfully                        catch err   gt              console log  Type send failed   err             toastr warning  Type send failed

User · Answer

Don t Return Empty Json  In My Case I was returning Empty Json String in  Net Core Web API Project   So I Changed My Code   From   return Ok      To   return Ok  Done      It seems you have to return some string or object   Hope this helps

[jquery] json parsing error syntax error unexpected end of input

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