[Solved] You wrote a pre_save signal handler but it never runs. Which is the most likely cause? — Ans: You did not register the signal handler properly | Django

Django - Signals

You wrote a pre_save signal handler but it never runs. Which is the most likely cause?

AYou forgot to import the signal module

BYou connected the signal after the model was saved

CYou used <code>post_save</code> instead of <code>pre_save</code>

DYou did not register the signal handler properly

Step-by-Step Solution

Solution:

Step 1: Check signal registration
If the handler is not registered properly (e.g., missing connect or @receiver), it won't run.
Step 2: Eliminate other causes
Importing signal module alone doesn't trigger handler; connecting after save is irrelevant; using post_save instead of pre_save changes timing but still runs.
Final Answer:
You did not register the signal handler properly -> Option D
Quick Check:
Signal handler must be registered to run [OK]

Quick Trick: Always register signal handlers with connect or @receiver [OK]

Common Mistakes:

MISTAKES

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You wrote a pre_save signal handler but it never runs. Which is the most likely cause?