'Depends on' in custom doctype

I need a solution, to hide a link / make Read Only a link in the child form after saving. (because even after saving the form, when the child table row opens the link drops down instead of showing the value):disappointed_relieved:
(1) Can I set it in the form itself ?
For example in the ‘Depends on’ field can I write something like “not task_id” (task_id is automatically generated when the row in the form is saved once)

(2) Write code? if then, how the link is made Read only after the form is saved? (N.B. Link field is in the child table)

Can anybody make me know the solution?


Refer link:-

Hello @shraddha Thank you… But my field is in Child table. I cannot make it Read only! I tried this code before.

Go through this link:-