[1.7.x] Fixed #22412 -- More nuanced advice re template filters and exceptions.

Thanks Tim for review.

Backport of 7e3834adc9 from master
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Carl Meyer 2014-04-09 23:19:55 -06:00 committed by Tim Graham
parent 941f947bfd
commit 0b43308e2d
1 changed files with 5 additions and 3 deletions

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@ -88,9 +88,11 @@ Custom filters are just Python functions that take one or two arguments:
For example, in the filter ``{{ var|foo:"bar" }}``, the filter ``foo`` would be
passed the variable ``var`` and the argument ``"bar"``.
Filter functions should always return something. They shouldn't raise
exceptions. They should fail silently. In case of error, they should return
either the original input or an empty string -- whichever makes more sense.
Usually any exception raised from a template filter will be exposed as a server
error. Thus, filter functions should avoid raising exceptions if there is a
reasonable fallback value to return. In case of input that represents a clear
bug in a template, raising an exception may still be better than silent failure
which hides the bug.
Here's an example filter definition: