How to filter link field in chid doctype

Hi

I want to show data in link field using query. Mu code is below:

frappe.ui.form.on("KD Assign", {
	
	
});
cur_frm.set_query("trader", "trader_kd", function(doc, cdt, cdn) {		
	return{
		query:"fmcg.fmcg.doctype.kd_assign.kd_assign.get_traders"			
	}
});

cur_frm.set_query("kds", "trader_kd", function(doc, cdt, cdn) {		
	return{
		query:"fmcg.fmcg.doctype.kd_assign.kd_assign.get_kds"	
	}
	frm.refresh();
});

but it is not showing statically after selecting… disappearing…
anybody know? plz

@Amalendu,

Try,

cur_frm.fields_dict['child_table_fieldname'].grid.get_field("link_fieldname").get_query = function(doc, cdt, cdn) {
	return {
		query: "filter_query"

	}
}

Thanks