Because I found with surprise that DataGrip shows irregular version of trigger function’s source code and pgAdmin 4 somehow refuses to show it at all (claiming internal server error) I had to find some other way how to access it.
Solution is described here “How can I show the content of a trigger with psql?“:
- in psql:
\dft– shows all trigger functions names
\dS <tablename>– shows names of triggers on given table
\df+ <functionname>– shows source code of trigger function