I need to exclude a business rule if submit from a specific table

[Jerome MAISETTI]

Hello All 

I have a field called "Time Worked Category" in the Task table that I automatically cascade to the Task Time Worked entry when submitting. 
However, I need this script to not cascade is the entry is created directly in the Task Time Worked table. 
How can I exclude my business rule to run and ignore the value in the Task form if the user inputs directly the Time into a new Task Time Worked entry ? 

Here is the code I have : 

function onBefore(current, previous) {
    //This function will be automatically called when this rule is processed.
    var taskID = current.task.sys_id;
    var workCategory = current.task.u_time_worked_category;
    var claimOvertime = current.task.u_claim_overtime;
    var actualTime = current.task.u_actual_start_time;
	if ((workCategory != '') && (workCategory != 'operational_work')){
		current.u_work_category = workCategory;
	}
    current.u_claim_overtime = claimOvertime;
    current.u_actual_time_creation = actualTime;
    if ((claimOvertime == true) || (current.u_claim_overtime == true)) {
        current.u_overtime_status == 'Requested';
    } else {
        current.u_overtime_status == '';
    }
}

[Ankur Bawiskar]

@Jerome MAISETTI 

simply check if the value is present or not on Task Time Worked table. if not then set it via script

function onBefore(current, previous) {
	//This function will be automatically called when this rule is processed.
	var taskID = current.task.sys_id;
	var workCategory;
	if(current.u_work_category == '')
		workCategory = current.task.u_time_worked_category;
	else
		workCategory = current.u_work_category;

	if(current.u_work_category == '')
		var claimOvertime = current.task.u_claim_overtime;
	var actualTime = current.task.u_actual_start_time;
	if ((workCategory != '') && (workCategory != 'operational_work')){		
		current.u_work_category = workCategory;
	}
	current.u_claim_overtime = claimOvertime;
	current.u_actual_time_creation = actualTime;
	if ((claimOvertime == true) || (current.u_claim_overtime == true)) {
		current.u_overtime_status == 'Requested';
	} else {
		current.u_overtime_status == '';
	}
}

If my response helped please mark it correct and close the thread so that it benefits future readers.

[Jerome MAISETTI]

Hello Ankur, 
The issue I have is that the Time Worked Category in the task table is never set to None, it got a default value. 
So I'm trying to see if I can do this via another way. 
I'm suspecting that I'll not have the choice to create a new field in Task Time Worked, in which one I copy the value from the Task, and if this new field is not none, override the category of the time worked entry with this value. 
What do you think ?