Child table fetching data problem

I have created a doctype named TimeLog .Its has a child table named log table . log table has 3 fields .in_time,out_time , time difference. Now the problem is i want my user can enter in_time and out_time and after that when he will press the update button or save button time difference will be calculated and will be showed in the ui. Now , for that i have to take entered values by user.But i am unable to find any solutions so far…i have been stuck here for almost 4 days.Please help me someone as i am newbie in erpnext development. Here is a picture so that you can understand my problem properly:

Hi @Arif_123,

have you looked into the custom scripts? A good starting point is the Developer Cheatsheet

Add a before_save or validate trigger, loop through the items and update the field (maybe make the difference field read-only).

Hope this helps.


you can calculate the time difference on before_save or after_save:

frappe.ui.form.on('Booking', "after_save", function(frm) {

    if (cur_frm.doc.log_table != undefined) {
        for (var i = 0; i < cur_frm.doc.log_table.length; i++) {
            cur_frm.doc.log_table[i].time_difference = cur_frm.doc.log_table[i].out_time - cur_frm.doc.log_table[i].in_time;

Hope this Solve yours query.

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Bro, i tried your piece.But unfortunately it didnot work for me in my case. Don’t know why.Can you suggest me any alternate way?

what error you got?
And can you share yours piece of code too.

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Brother it didnot show me error that’s the main problem. I opened the console and checked whether there is any error or not.But i found nothing.Here is the piece of my parent doctype name is “TimeLog”.

For Time Difference Please Refer below link

that will help you in calculating the time difference.

Error is that in_time and out_time these two are string values that why the above code was not working.

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Bro, i have done everything as you instructed:

Still no improvement. My TIME DIFFERENCE field is READ ONLY TYPE so i parsed hour,minute,second to String like this:


and ran bench build command. Still failing every time :cry:

now feeling useless as a developer :‘( :’(

Just replace below code with your code

frappe.ui.form.on('TimeLog', "before_save", function(frm) {
    if (cur_frm.doc.log_table != undefined) {
        var hour=0;
        var minute=0;
        var second=0;
        var outTime = 0;
        var inTime = 0;
        for (var i = 0; i < cur_frm.doc.log_table.length; i++) {
            outTime = cur_frm.doc.log_table[i].out_time;
            inTime = cur_frm.doc.log_table[i].in_time;
            var splitOutTime= outTime.split(':');
            var splitInTime= inTime.split(':');
            hour = Math.abs(parseInt(splitOutTime[0])-parseInt(splitInTime[0]));
            minute = Math.abs(parseInt(splitOutTime[1])-parseInt(splitInTime[1]));
            hour = hour + minute/60;
            minute = minute%60;
            second = Math.abs(parseInt(splitOutTime[2])-parseInt(splitInTime[2]));
            minute = minute + second/60;
            second = second%60;
            cur_frm.doc.log_table[i].difference_time = parseInt(hour)+':'+parseInt(minute)+':'+parseInt(second)

Don’t worry! You’ll find a way out. Happy Practicing!