Way to get at parsed trigger 'WHEN' clause expression?

Folks,

I see that psql's \d displays trigger information of a table by making a call to pg_catalog.pg_get_triggerdef(), which abstracts away most all need to parse the contents of system catalog pg_trigger. However, we'd like to be able to get at a human readable representation of just the WHEN clause of the trigger expression. Function pg_get_expr() looked likely, but fails when fed a pgqual value from pg_trigger ala:

ERROR: bogus varno: 2

I suspect that it is falling over dead trying to parse the representation of NEW and / or OLD. Anything built in, or should we just make call to pg_catalog.pg_get_triggerdef() and parse out the WHEN clause text?

Thanks!
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James Robinson
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