Update field through workflow ONLY when no related records are present

[Guido1982]

I have a use case where I hope I can use a workflow in stead of coding:

I want to update the field 'dateinservice' in Assets. I have a custom module called 'ServiceJob' that is related to Assets through a M:M relation. Now I want to do the following:

When an asset is saved, a workflow should check if only one ServiceJob is related. If so, the 'dateinservice' field should be filled with a field from that related ServiceJob record. If the no. or related ServiceJob records is 0 or greater than 1, it should do nothing. Do we have a workflow expression function that counts related records, or one that could be 'abused' to do so?

[joebordes]

I think you are going to have to create a custom function for that.

[Guido1982]

Will do and PR it.