What is an action filter?
PICTURE THIS: HOW TO EXPLAIN IT
Simple meaning
It runs before or after an action so I can log, authorize, or short-circuit.
WHY — Filters instead of guessing?
Why interviewers care about Filters:
who only read docs from people who shipped.
and tied to .NET MVC work.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1It runs before or
after an action so I can log, authorize, or short-circuit.
- 2Authorize and Exception filters
are the ones I mention first.
- 3Global filters apply to
every action unless I skip them.
- 4Give an example
One tiny concrete case you can say aloud.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
It runs before or after an action so I can log, authorize, or short-circuit. Authorize and Exception filters are the ones I mention first.