Scripting - How to catch Raise from db function

Ignition
1

I’m on 8.1.20

I have a PostgreSQL DB with functions that RAISE exception, I search the way to catch the RAISE message (highlighted)

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2

Database errors come through to ignition as java errors so you should use java.lang.Exception or preferably java.lang.Throwable to catch them like

import java.lang.Throwable
try:
    # some sql operation
except java.lang.Throwable, e:
    # catch exception

You may then want to examine e.cause to see the specific error. I use this to good effect.

2 Likes
3

I havent used cause before, but I tend to use:

import traceback
system.perspective.print(traceback.format_exc())

Also, I use

from java.lang import Throwable
try:

except Throwable:
   import traceback....

It just avoids repeating things a bit

1 Like
4

The reason I like e.cause is its the exact error which allows me to easily catch for certain expected errors (my application is all forms so I have to expect Users to mess up)

so it allows me to do something like this

			if 'Duplicate entry' in str(e.cause):
				message = self.parseUniqueConstraintViolationErrorMessage(e, action)
			elif 'cannot be null' in str(e.cause):
				message = self.parseNullMessage(e, action)
			elif "Data too long" in str(e.cause):
				message = self.parseTooLongMessage(e, action)
			elif "Cannot delete or update a parent row" in str(e.cause) or "Cannot add or update a child row" in str(e.cause):
				message = self.parseFKConstraintMessage(e, action)
			elif "EmptyStringError" in str(e.cause):
				# Custom error we throw from the database via string.  Error messages look like "EmptyStringError, rest of message here"
				message = self.parseEmptyStringError(e, action)
			else:

Then in my else is where I will log the entire stack trace as it's an unexpected database error.

1 Like