Read Form Post Parameter of recorded web performance test

Question

I have recorded web performance test in VS 2015 and added Form Post parameter in one web performance project.

I have one more C# class library project already exists in my solution. Now I wish to read this Form Post Parameter value in a C# class file so that I can make it dynamic. Can anyone suggest how can I read that. Currently it is being read hard coded as

public override void PreWebTest(object sender, PreWebTestEventArgs e)
{
     Object obj = null;

     obj = e.WebTest.Context["XXXX"];
     ...
}

Here I wish to put the value of the object from Form Post Parameter set in my recorded Webtest