Why would my array on my MVC Controller be null on Ajax Postback

Question

Here is my array:

{latlng: [{lat: 41.9841092242239, lng: -87.6459866168}, {lat: 41.948650308164744, lng: -87.64431828280067}, {lat: 41.94833112697515, lng: -87.644017875391}]

Here is my javascript code:

 var postedData = JSON.stringify({
 latlng: boundaries
 });
 alert("here are your boundaries so far : " + postedData);
 $.ajax({
 url: '/Communities/UpdateBoundaries',
 type: "POST",
 traditional: true,
 contentType: "application/json",
 data: postedData,
 datatype: "json",
 success: function () {
 console.log('success!!');
 }
 });
 }

and here is my controller: where boundaries is my incoming array of latlng, but it is coming in null.

 [HttpPost]
 public ActionResult UpdateBoundaries(List<latLng> boundaries)
 {
 return View();
 }

Answer 1

Change

var postedData = JSON.stringify({latlng: boundaries});

to

var postedData = JSON.stringify(boundaries);

This is because the action parameter is an array. If it were a type that contained an array property with property name latlng then you pass it in the same manner you did in your existing code.

• Paul T. Rykiel: i received an error on JSON.Stringify not a function
• Igor: @PaulT.Rykiel - lowercase s in stringify. javascript is case sensitive.
• Igor: @PaulT.Rykiel - you are running this in a browser right? Try re-typing it as maybe it was not copied from the browser correctly: JSON.stringify.
• Paul T. Rykiel: Nevermind, I don't know what I did wrong before, but this time it worked.
• Igor: @PaulT.Rykiel - good deal! If this solves your problem please consider marking it as the answer.