Merge branch 'feature/extensible-models' into 'master'

Let model extensions define new fields

See merge request AlekSIS/AlekSIS!129

aleksis/core/migrations/0001_initial.py

@@ -26,7 +26,7 @@ class Migration(migrations.Migration):
             options={
                 'ordering': ['short_name', 'name'],
             },
-            bases=(models.Model, aleksis.core.mixins.ExtensibleModel),
+            bases=(aleksis.core.mixins.ExtensibleModel,),
         ),
         migrations.CreateModel(
             name='School',
@@ -98,7 +98,7 @@ class Migration(migrations.Migration):
             options={
                 'ordering': ['last_name', 'first_name'],
             },
-            bases=(models.Model, aleksis.core.mixins.ExtensibleModel),
+            bases=(aleksis.core.mixins.ExtensibleModel,),
         ),
         migrations.AddField(
             model_name='group',

aleksis/core/migrations/0008_extended_data.py

+# Generated by Django 3.0.2 on 2020-01-18 21:56
+
+import django.contrib.postgres.fields.jsonb
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0007_create_admin_user'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='group',
+            name='extended_data',
+            field=django.contrib.postgres.fields.jsonb.JSONField(default=dict),
+        ),
+        migrations.AddField(
+            model_name='person',
+            name='extended_data',
+            field=django.contrib.postgres.fields.jsonb.JSONField(default=dict),
+        ),
+    ]

aleksis/core/mixins.py

@@ -5,10 +5,12 @@ from django.db import models
 from django.db.models import QuerySet
 
 from easyaudit.models import CRUDEvent
+from jsonstore.fields import JSONField, JSONFieldMixin
 
 
-class ExtensibleModel(object):
-    """ Allow injection of code from AlekSIS apps to extend model functionality.
+class ExtensibleModel(models.Model):
+    """ Allow injection of fields and code from AlekSIS apps to extend
+    model functionality.
 
     After all apps have been loaded, the code in the `model_extensions` module
     in every app is executed. All code that shall be injected into a model goes there.
@@ -19,6 +21,8 @@ class ExtensibleModel(object):
 
        from datetime import date, timedelta
 
+       from jsonstore import CharField
+
        from aleksis.core.models import Person
 
        @Person.property
@@ -29,6 +33,8 @@ class ExtensibleModel(object):
        def age(self) -> timedelta:
            return self.date_of_birth - date.today()
 
+       Person.field(shirt_size=CharField())
+
     For a more advanced example, using features from the ORM, see AlekSIS-App-Chronos
     and AlekSIS-App-Alsijil.
 
@@ -37,6 +43,8 @@ class ExtensibleModel(object):
         - Dominik George <dominik.george@teckids.org>
     """
 
+    extended_data = JSONField(default=dict, editable=False)
+    
     @classmethod
     def _safe_add(cls, obj: Any, name: Optional[str]) -> None:
         # Decide the name for the attribute
@@ -48,12 +56,12 @@ class ExtensibleModel(object):
             else:
                 raise ValueError("%s is not a valid name." % name)
 
-        # Verify that property name does not clash with other names in the class
+        # Verify that attribute name does not clash with other names in the class
         if hasattr(cls, prop_name):
             raise ValueError("%s already used." % prop_name)
 
-        # Add function wrapped in property decorator if we got here
-        setattr(cls, prop_name, obj)
+        # Let Django's model magic add the attribute if we got here
+        cls.add_to_class(name, obj)
 
     @classmethod
     def property(cls, func: Callable[[], Any], name: Optional[str] = None) -> None:
@@ -67,6 +75,32 @@ class ExtensibleModel(object):
 
         cls._safe_add(func, func.__name__)
 
+    @classmethod
+    def field(cls, **kwargs) -> None:
+        """ Adds the passed jsonstore field. Must be one of the fields in
+        django-jsonstore.
+
+        Accepts exactly one keyword argument, with the name being the desired
+        model field name and the value the field instance.
+        """
+
+        # Force kwargs to be exactly one argument
+        if len(kwargs) != 1:
+            raise TypeError("field() takes 1 keyword argument but %d were given" % len(kwargs))
+        name, field = kwargs.popitem()
+
+        # Force the field to be one of the jsonstore fields
+        if JSONFieldMixin not in field.__class__.__mro__:
+            raise TypeError("Only jsonstore fields can be added to models.")
+
+        # Force use of the one JSONField defined in this mixin
+        field.json_field_name = "extended_data"
+
+        cls._safe_add(field, name)
+
+    class Meta:
+        abstract = True
+
 
 class CRUDMixin(models.Model):
     class Meta:

aleksis/core/models.py

@@ -64,7 +64,7 @@ class SchoolTerm(models.Model):
         verbose_name_plural = _("School terms")
 
 
-class Person(models.Model, ExtensibleModel):
+class Person(ExtensibleModel):
     """ A model describing any person related to a school, including, but not
     limited to, students, teachers and guardians (parents).
     """
@@ -159,7 +159,7 @@ class Person(models.Model, ExtensibleModel):
         return self.full_name
 
 
-class Group(models.Model, ExtensibleModel):
+class Group(ExtensibleModel):
     """Any kind of group of persons in a school, including, but not limited
     classes, clubs, and the like.
     """

pyproject.toml

@@ -62,6 +62,7 @@ Celery = {version="^4.4.0", optional=true, extras=["django", "redis"]}
 django-celery-results = {version="^1.1.2", optional=true}
 django-celery-beat = {version="^1.5.0", optional=true}
 django-celery-email = {version="^3.0.0", optional=true}
+django-jsonstore = "^0.4.1"
 
 [tool.poetry.extras]
 ldap = ["django-auth-ldap"]