How to handle search parameter in Datatables

I have the following code:

Controller method

public JsonResult GetNonstandardProgram(
    int draw, 
    int start, 
    int length, 
    string search = null /* or string search or string[] search = null */
    )

      

        
        
        
      

    

Data sent by datatables

...&search%5Bvalue%5D=somethingToSearch&search%5Bregex%5D=false

      

        
        
        
      

    

and i dont know how to handle this part

&search[value]=somethingToSearch

      

        
        
        
      

    

because in the Controller the string parameter "search" is always null.

What am I doing wrong?