How to create parameters with regex patterns?

[PaulWay]

Hi there!

I'm just coming to drf_spectacular after using drf_yasg for many years, and I'm having to change all my openapi.Parameter definitions over to OpenApiParameter. What's really puzzling me is that I can set type=OpenApiTypes.REGEX, but I cannot set a pattern when initialising the parameter. I understand that serializers can use Regex validators, but I can't see how to add a regex pattern to a parameter.

I'm prepared to write the code to support it, but I thought I'd check first the correct way of setting a regex pattern on a parameter.

Thanks in advance,

Paul

[tfranzel]

Hi!

it is simply an oversight. I just added the possibility to add a pattern via the interface. You can also do type=str as the format is only informative and should yield the same outcome.

OpenApiParameter(name='test', type=OpenApiTypes.REGEX, pattern='^[0-9]{3}$')
OpenApiParameter(name='test', type=str, pattern='^[0-9]{3}$') # alternatively

Until this is released you can also do it manually with (raw schema support)

OpenApiParameter(name='test', type={'pattern': '^[0-9]{3}$', 'type': 'string', 'format': 'regex'})

[PaulWay]

OK, interesting. I'd have to check my code at work, but I did try to add the pattern keyword to the OpenApiParameter declaration and it stopped with an error that pattern wasn't a recognised argument.

[tfranzel]

@PaulWay you are reading it wrong 😄 I just added the parameter with above commit. You refer to the pattern that is part of the dict that I gave to the type argument.

you can write arbitrary schemas into a dict and pass it to type. this is a fallback mechanism available all throughout spectacular.

[PaulWay]

Ah - I'm with you now :-)

[aupi0]

On a similar note would it be possible/is there already a method to put a max_length constraint on OpenApiParameters (similar to fields)?

[tfranzel]

@aupi0 no sry there is not. You would need to write a small custom schema dict as outlined above. The interface is already somewhat large and I don't want to dilute it further. max_length would not be the only potential addition, and adding all other possibilities simply does not scale. max_length is not special in that regard.

[tfranzel]

I'll close this issue as the initial ask as added