a viewset's action list gets "head" added to it, but only after being called at least once

[rtpg]

https://github.com/encode/django-rest-framework/blame/853969c69c815be69513c2f63a41285858a45352/rest_framework/viewsets.py#L106-L107

We didn't have head set in our actions on a viewset, but head would suddenly appear in a viewset's actions, but seemingly randomly.

This way of filling in head in actions means that before you call a viewset at least once, it will have one set of actions, but afterwards it would have another.

This is surprising to me, and I have a hard time imagining it to be the right solution here. But perhaps I am missing a detail.

[browniebroke]

Seems like this behaviour is due to what was done in #7223 for #6196

Do you have a suggestion on how to fix that?

[Sajadrahimi]

I guess the initial idea of changing SimpleRouter and action decorator was the better way to go with. I applied to changes here, it seems fine to me if you're fine with it I can open a PR @browniebroke .

[auvipy]

you can open a pr for review

[mag123c]

Taking this on since no PR has been opened yet.

[Natgho]

This solution seems quite sufficient. It will eliminate mutation-related errors;
#9853 mutation source

[browniebroke]

I'm not sure... The OP flags the mutation problem but is not clear on expected behaviour. The current fix makes sure head is never present in the viewset actions, but one could argue that it should always be there

[Natgho]

I'm not sure... The OP flags the mutation problem but is not clear on expected behaviour. The current fix makes sure head is never present in the viewset actions, but one could argue that it should always be there

Should the basic flow of behavior change? In this logic, partially yes. What if someone only wants to accept "GET" requests but does not accept "HEAD" requests? I think the current solution addresses this.