Calculated column in Task List is not updating when Task is changed

Question

Scenario:

1. I have a Tasks List

2. A new calculated column added to it Task_ID

   a. Formula used -

   =CONCATENATE("TL_",ID)

It produces a column having values like TL_1, TL_2 .. and so on.

Now whenever anything changes in a list item (may be Task Status or anything else) the calculated column value changes to TL_

I have to goto the calculated column in the List Settings and hit OK button to re calculate the values.

How can I correct this auto update the values?

Answer 1

The ID field you are trying to use in your Calculated Column is not known until the Item is saved . Hence using it in your calculated column may not give you the required output.You can use an event handler or a workflow to update the list items. My preference would be a simple workflow that runs when the items are created.