Quick Action for Activity: custom field for account lookup

Question

I have created a custom quick action for the activity in Account. All lightning experience.

The custom quick action is like a new task. I need to add a field to show which account this is coming from. So the field is called "related to", and it is supposed to be a lookup, related to the current account that this task is going to be created.

I am wondering how I can populate this field. I tried to search online and saw a few hints like a lookup field + process builder, or formula field. But still haven't been able to make it work.

Answer 1

When you create an Object-Specific Quick Action to create a child record, and there is exactly one writeable relationship field between the child and the parent*, Salesforce automatically knows to populate that field for you.

If you create a new Task-creating Quick Action on Account and review the results, you'll find that Salesforce has automatically selected the Related To relationship (WhatId):

Should you create a Quick Action in a situation where the child object has more than one relationship to the parent, you'll have an opportunity to choose which relationship you would like to be populated when you invoke the Quick Action. With only one relationship field present, you won't see the option because Salesforce can infer what is needed.

* Task has a second relationship with Account, AccountId - but it's not writeable and is automatically calculated by the system.