MVC controller's string[] parameter is null when posting JSON data

Question

I post data with jQuery but I have a problem with array data. The values supplied to the MVC controller are always null.

This is my JavaScript code:

 var FilterCategory = $('input:checkbox:checked').map(function () {
                return this.value;
            }).get();
 var posting = $.post(url, { cursorid: lastid, CatFilter: FilterCategory });

The form data from the network:

cursorid:5434cdc84ba4dd0c40396851
Filter[]:1
Filter[]:3
Filter[]:4

Here's the C# side:

public ActionResult GetDataTweets(string cursorid,string[] CatFilter)
    {
       bla bla
    }

cursorid has a value, but CatFilter is null.

What do I need to do to have the correct value supplied to CatFilter?

Answer 1

This code here:

var posting = $.post(url, { cursorid: lastid, CatFilter: FilterCategory });

From MVC's perspective it's sending a class, so you need a reciprocal C# class to package the data. Create a class to handle that data, for example:

I am assuming your CatFilter array is a string array:

public class Data{
  public string cursorid { get; set;}
  public string[] CatFilter {get; set;}
}

Then change your controller:

public ActionResult GetDataTweets(Data data)
{
   var s1 = data.cursorid;
   var s2 = data.CatFilter[0];
}

if CatFilter is a class then you'd need to create a CatFilter class to map to the javascript version.