Hi,
the option using custom handler is also possible. You'll need to write the code to get the document foreign key value and then assign it to the document name field. Please, see the
API examples in Site Manager -> Support section to see how to work with documents in the API. Or, also in the
tree node handler is a sample of code.
The other way could be that you will bind given field to be the source of the document name for given document type. On the
Fields tab you can see that under the fields there are two drop downs you can use for this purpose. Or, you can aslo try adding a
macro as a default value for given field and disable editing.
Best regards,
Juraj Ondrus