"ExtensionType" has no attribute "get_values_for_type"

[mimi89999]

Hello,

I used the example from https://cryptography.io/en/latest/x509/reference/#cryptography.x509.SubjectAlternativeName.get_values_for_type:

from cryptography import x509
from cryptography.x509.oid import ExtensionOID

cert = x509.load_pem_x509_certificate(b"")
san_ext = cert.extensions.get_extension_for_oid(ExtensionOID.SUBJECT_ALTERNATIVE_NAME)
san_names = san_ext.value.get_values_for_type(x509.DNSName)

print(san_names)

When I run mypy on it, I'm getting the following error:
error: "ExtensionType" has no attribute "get_values_for_type" [attr-defined]

Versions:

cryptography==46.0.2
mypy==1.18.2

[alex]

The issue here is that get_extension_for_oid doesn't return a specifically typed extension.

You can either use a type assertion on san_ext, or you can use cert.extensions.get_extension_for_class(x509.SubjectAlternativeName).

[github-actions]

This issue has been waiting for a reporter response for 3 days. It will be auto-closed if no activity occurs in the next 5 days.

[mimi89999]

Thanks. After using get_extension_for_class I have the correct type. Maybe that should be explained in the doc?

[reaperhulk]

We'd be happy to take a docs PR that explains this, but glad you were able to resolve your issue!