How do i pass the dynamic fields

[xts-velkumars]

Hi Every one,
I need to achieve below, could any one suggest me?

1. I need to pass the fields dynamically from the controller, how do i do that?
2. I'm using query builder on my model pop-up, based on the grid row selected problem is i need to clear the previous conditions (meaning when ever pop-up loaded i need to reset my condition or either i saved the SQL query on my database so based on the value i need to dynamically construct the condition based on by value)