Use criteria of a related record in process builder?

Question

I'm in the process of going through an org merge.  In the source org they had workflows triggered by users simply clicking a checkbox, which would then send upto 10 different tasks out to users.  Clearly I hate how that's done, so I asked for logic in order automate the process/get rid of so many tasks.  

I have a custom "Membership" object that has a master detail to the Account object.  

Here is an example of the criteria of one of the "checkboxes":

A new Membership record is created, where:
Status__c = Active
Enterprise = null
Approved = true
AND  (a different Membership record, related to the same Account)
Status = Former
End day within past 7 days
Enterprise = Fidelity

After logic is met, a new Task record is created that has different checkboxes of the various items needing to be done. 

Is it possible to build criteria off of another record in PB?  Or is Apex my only option?

Answer 1

It is possible to use criteria from related records in Process Builder, but you need to be able to traverse a relationship path from the starting record to get there. For example, you could go from Membership to a field on Account, tracing through the child-to-parent relationship, and you could go further up to the Account's parent, and so forth.

What you cannot do is descend from a related parent to a different child, unless the parent also has a lookup field to that other child.

A more common mechanism to support this, though, is to roll up the information needed from other child records to the parent so that the data is directly accessible from a Process on a child.

Here, you could roll up to a Number field, Recent_Former_Memberships__c, on the Account the count of Membership records which meet the criteria

Status = Former
End day within past 7 days
Enterprise = Fidelity

Then, your Process on Membership__c can directly access that data.

Unfortunately, since this is a dated rollup, you can't do it using native roll-up summary fields. You would need to use DLRS in Scheduled mode, or similar tool, to achieve that declaratively.

The alternative, overall, would be to implement this functionality as an Apex trigger or a Process + Flow sequence, where you're able to run a query/Fast Lookup for arbitrary related records.