Add and use convenience ClaimFieldDefault

CHANGELOG.rst

@@ -2,6 +2,14 @@
 Changelog
 =========
 
+0.18.0 (2024-06-1?)
+===================
+
+Small feature release
+
+* Added ``mozilla_django_oidc_db.fields.ClaimFieldDefault`` to specify default values
+  for ``ClaimField`` in a less verbose way.
+
 0.17.0 (2024-05-28)
 ===================
 

docs/reference.rst

@@ -23,6 +23,9 @@ Models
 .. automodule:: mozilla_django_oidc_db.models
     :members:
 
+.. automodule:: mozilla_django_oidc_db.fields
+    :members:
+
 Utils
 =====
 

mozilla_django_oidc_db/fields.py

@@ -1,9 +1,37 @@
 from django.db import models
+from django.utils.deconstruct import deconstructible
 from django.utils.translation import gettext_lazy as _
 
 from django_jsonform.models.fields import ArrayField
 
 
+@deconstructible
+class ClaimFieldDefault:
+    """
+    Callable default for ClaimField.
+
+    Django's ArrayField requires a callable to be passed for the ``default`` kwarg, to
+    avoid sharing a mutable value shared by all instances. This custom class provides
+    a straight-forward interface so that defaults can be provided inline rather than
+    requiring a function to be defined at the module level, since lambda's cannot be
+    serialized for migrations.
+
+    Usage:
+
+    >>> field = ClaimField(default=ClaimFieldDefault("foo", "bar"))
+    >>> field.get_default()  # ["foo", "bar"]
+    """
+
+    def __init__(self, *bits: str):
+        self.bits = list(bits)
+
+    def __eq__(self, other) -> bool:
+        return self.bits == other.bits
+
+    def __call__(self) -> list[str]:
+        return self.bits
+
+
 class ClaimField(ArrayField):
     """
     A field to store a path to claims holding the desired value(s).

mozilla_django_oidc_db/migrations/0002_migrate_to_claim_field.py

@@ -69,7 +69,7 @@ class Migration(migrations.Migration):
                     max_length=50, verbose_name="claim path segment"
                 ),
                 blank=True,
-                default=mozilla_django_oidc_db.models.get_default_groups_claim,
+                default=mozilla_django_oidc_db.fields.ClaimFieldDefault("roles"),
                 help_text="The name of the OIDC claim that holds the values to map to local user groups.",
                 size=None,
                 verbose_name="groups claim",
@@ -82,7 +82,7 @@ class Migration(migrations.Migration):
                 base_field=models.CharField(
                     max_length=50, verbose_name="claim path segment"
                 ),
-                default=mozilla_django_oidc_db.models.get_default_username_claim,
+                default=mozilla_django_oidc_db.fields.ClaimFieldDefault("sub"),
                 help_text="The name of the OIDC claim that is used as the username",
                 size=None,
                 verbose_name="username claim",

mozilla_django_oidc_db/models.py

@@ -15,7 +15,7 @@
 from solo import settings as solo_settings
 from solo.models import SingletonModel
 
-from .fields import ClaimField
+from .fields import ClaimField, ClaimFieldDefault
 from .typing import ClaimPath, DjangoView
 
 
@@ -41,14 +41,6 @@ def get_claim_mapping() -> dict[str, list[str]]:
     }
 
 
-def get_default_username_claim() -> list[str]:
-    return ["sub"]
-
-
-def get_default_groups_claim() -> list[str]:
-    return ["roles"]
-
-
 class OpenIDConnectConfigBase(SingletonModel):
     """
     Defines the required fields for a config to establish an OIDC connection
@@ -240,7 +232,7 @@ def oidcdb_username_claim(self) -> ClaimPath:
         """
         The claim to read to extract the value for the username field.
         """
-        return get_default_username_claim()
+        return ["sub"]
 
     @property
     def oidcdb_userinfo_claims_source(self) -> UserInformationClaimsSources:
@@ -264,7 +256,7 @@ class OpenIDConnectConfig(OpenIDConnectConfigBase):
 
     username_claim = ClaimField(
         verbose_name=_("username claim"),
-        default=get_default_username_claim,
+        default=ClaimFieldDefault("sub"),
         help_text=_("The name of the OIDC claim that is used as the username"),
     )
 
@@ -275,7 +267,7 @@ class OpenIDConnectConfig(OpenIDConnectConfigBase):
     )
     groups_claim = ClaimField(
         verbose_name=_("groups claim"),
-        default=get_default_groups_claim,
+        default=ClaimFieldDefault("roles"),
         help_text=_(
             "The name of the OIDC claim that holds the values to map to local user groups."
         ),

tests/test_models.py

@@ -3,6 +3,7 @@
 
 import pytest
 
+from mozilla_django_oidc_db.fields import ClaimFieldDefault
 from mozilla_django_oidc_db.models import OpenIDConnectConfig
 
 
@@ -58,3 +59,8 @@ def test_validate_username_field_not_in_claim_mapping():
     assert "claim_mapping" in err_dict
     error = _("The username field may not be in the claim mapping")
     assert error in err_dict["claim_mapping"]
+
+
+def test_claim_field_default_equality():
+    assert ClaimFieldDefault("foo", "bar") == ClaimFieldDefault("foo", "bar")
+    assert ClaimFieldDefault("foo", "bar") != ClaimFieldDefault("bar", "foo")