PB-2354: Add CF extension fields

app/stac_api/admin.py

@@ -326,6 +326,12 @@ class Media:
                 )
             }
         ),
+        ('CF Extension', {
+            'fields': (
+                'cf_standard_name',
+                'unit',
+            )
+        }),
     )
 
     list_display = ['name', 'collection', 'collection_published']

app/stac_api/managers.py

@@ -289,16 +289,28 @@ def filter_by_query(self, query):
             for operator in query[attribute]:
                 value = query[attribute][operator]  # get the values given by the operator
 
-                if attribute in ["updated", "created"]:
+                if attribute in ["updated", "created", "cf:standard_name", "unit"]:
                     prefix = ""
                 else:
                     prefix = "properties_"
 
+                model_field = attribute.replace(":", "_")
+
                 # __eq does not exist, but = does it as well
                 if operator == 'eq':
-                    query_filter = f"{prefix}{attribute}"
+                    query_filter = f"{prefix}{model_field}"
                 else:
-                    query_filter = f"{prefix}{attribute}__{operator.lower()}"
+                    query_filter = f"{prefix}{model_field}__{operator.lower()}"
+                # PB-2354: This is a bug: As it is now, we cannot query by multiple fields
+                # because we return already for the first operator.
+                #
+                # See this test to demonstrate the bug:
+                #
+                #    tests.tests_10.test_search_endpoint.SearchEndpointTestCF.test_multiple_cf
+                #
+                # We keep this is as it is as noone seemed to use that feature so far.
+                # Instead, we intend to fix it properly by replacing the Query Extension by the
+                # Filter Extension, which is the recommended solution anyway.
                 return self.filter(**{query_filter: value})
 
 

app/stac_api/migrations/0080_item_cf_standard_name_item_unit.py

@@ -0,0 +1,34 @@
+# Generated by Django 5.2.13 on 2026-08-10 16:43
+
+import pgtrigger.compiler
+import pgtrigger.migrations
+
+from django.db import migrations
+from django.db import models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('stac_api', '0079_add_stac_extensions_to_meteoschweiz_collections'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='item',
+            name='cf_standard_name',
+            field=models.CharField(
+                blank=True,
+                help_text='Corresponds to the CF Standard Name from the CF Standard Name Table.',
+                max_length=255,
+                null=True
+            ),
+        ),
+        migrations.AddField(
+            model_name='item',
+            name='unit',
+            field=models.CharField(
+                blank=True, help_text='Corresponds to the CF units.', max_length=255, null=True
+            ),
+        ),
+    ]

app/stac_api/migrations/0081_remove_item_update_collection_child_trigger_etag_only_and_more.py

@@ -0,0 +1,47 @@
+# Generated by Django 5.2.13 on 2026-08-11 15:15
+
+import pgtrigger.compiler
+import pgtrigger.migrations
+
+from django.db import migrations
+from django.db import models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('stac_api', '0080_item_cf_standard_name_item_unit'),
+    ]
+
+    operations = [
+        pgtrigger.migrations.RemoveTrigger(
+            model_name='item',
+            name='update_collection_child_trigger_etag_only',
+        ),
+        migrations.AddIndex(
+            model_name='item',
+            index=models.Index(fields=['cf_standard_name'], name='item_cf_standard_name_idx'),
+        ),
+        migrations.AddIndex(
+            model_name='item',
+            index=models.Index(fields=['unit'], name='item_unit_idx'),
+        ),
+        pgtrigger.migrations.AddTrigger(
+            model_name='item',
+            trigger=pgtrigger.compiler.Trigger(
+                name='update_collection_child_trigger_etag_only',
+                sql=pgtrigger.compiler.UpsertTriggerSql(
+                    condition=
+                    'WHEN (OLD."cf_standard_name" IS DISTINCT FROM (NEW."cf_standard_name") OR OLD."collection_id" IS DISTINCT FROM (NEW."collection_id") OR OLD."created" IS DISTINCT FROM (NEW."created") OR OLD."etag" IS DISTINCT FROM (NEW."etag") OR OLD."forecast_duration" IS DISTINCT FROM (NEW."forecast_duration") OR OLD."forecast_horizon" IS DISTINCT FROM (NEW."forecast_horizon") OR OLD."forecast_perturbed" IS DISTINCT FROM (NEW."forecast_perturbed") OR OLD."forecast_reference_datetime" IS DISTINCT FROM (NEW."forecast_reference_datetime") OR OLD."forecast_variable" IS DISTINCT FROM (NEW."forecast_variable") OR OLD."geometry" IS DISTINCT FROM (NEW."geometry") OR OLD."id" IS DISTINCT FROM (NEW."id") OR OLD."name" IS DISTINCT FROM (NEW."name") OR OLD."properties_datetime" IS DISTINCT FROM (NEW."properties_datetime") OR OLD."properties_end_datetime" IS DISTINCT FROM (NEW."properties_end_datetime") OR OLD."properties_expires" IS DISTINCT FROM (NEW."properties_expires") OR OLD."properties_start_datetime" IS DISTINCT FROM (NEW."properties_start_datetime") OR OLD."properties_title" IS DISTINCT FROM (NEW."properties_title") OR OLD."stac_extensions" IS DISTINCT FROM (NEW."stac_extensions") OR OLD."total_data_size" IS DISTINCT FROM (NEW."total_data_size") OR OLD."unit" IS DISTINCT FROM (NEW."unit"))',
+                    declare='DECLARE child stac_api_Item%ROWTYPE;',
+                    func=
+                    "\n-- update related collection\nchild = COALESCE(NEW, OLD);\nUPDATE stac_api_collection SET\n    etag = public.gen_random_uuid()\nWHERE id = child.collection_id;\n\nRAISE INFO '%: updated collection.id=% due to Item.id=%',\n    TG_NAME, child.collection_id, child.id;\n\nRETURN child;\n",
+                    hash='0308e4b3217a2be3890fde8659088ee924d8c59a',
+                    operation='UPDATE',
+                    pgid='pgtrigger_update_collection_child_trigger_etag_only_bee6a',
+                    table='stac_api_item',
+                    when='AFTER'
+                )
+            ),
+        ),
+    ]

app/stac_api/migrations/0082_alter_collection_stac_extensions_enabled_and_more.py

@@ -0,0 +1,59 @@
+# Generated by Django 5.2.13 on 2026-08-11 17:03
+
+import django.contrib.postgres.fields
+from django.db import migrations
+from django.db import models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('stac_api', '0081_remove_item_update_collection_child_trigger_etag_only_and_more'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='collection',
+            name='stac_extensions_enabled',
+            field=django.contrib.postgres.fields.ArrayField(
+                base_field=models.CharField(
+                    choices=[(
+                        'https://stac-extensions.github.io/timestamps/v1.1.0/schema.json',
+                        'Timestamps'
+                    ),
+                             (
+                                 'https://stac-extensions.github.io/forecast/v0.2.0/schema.json',
+                                 'Forecast'
+                             ), ('https://stac-extensions.github.io/cf/v1.0.0/schema.json', 'CF')],
+                    max_length=255
+                ),
+                blank=True,
+                default=list,
+                help_text=
+                'STAC extensions that are enabled for the Items in this Collection. It defines which STAC extensions are allowed to be used by the Items in this Collection. This field is for internal/admin use only, it is not exposed through the STAC API.',
+                size=None
+            ),
+        ),
+        migrations.AlterField(
+            model_name='item',
+            name='stac_extensions',
+            field=django.contrib.postgres.fields.ArrayField(
+                base_field=models.CharField(
+                    choices=[(
+                        'https://stac-extensions.github.io/timestamps/v1.1.0/schema.json',
+                        'Timestamps'
+                    ),
+                             (
+                                 'https://stac-extensions.github.io/forecast/v0.2.0/schema.json',
+                                 'Forecast'
+                             ), ('https://stac-extensions.github.io/cf/v1.0.0/schema.json', 'CF')],
+                    max_length=255
+                ),
+                blank=True,
+                default=list,
+                help_text=
+                "STAC extensions used by this Item. Defined as JSON schema URLs. Must be a subset of the Collection's stac_extensions_enabled field.",
+                size=None
+            ),
+        ),
+    ]

app/stac_api/models/item.py

@@ -86,6 +86,9 @@ class Meta:
             models.Index(fields=['forecast_duration'], name='item_fc_duration_idx'),
             models.Index(fields=['forecast_variable'], name='item_fc_variable_idx'),
             models.Index(fields=['forecast_perturbed'], name='item_fc_perturbed_idx'),
+            # CF extension properties are "queryable" in the search endpoint
+            models.Index(fields=['cf_standard_name'], name='item_cf_standard_name_idx'),
+            models.Index(fields=['unit'], name='item_unit_idx'),
             # combination of datetime and start_ and end_datetimes are used in
             # managers.py:110 and following
             models.Index(
@@ -212,6 +215,17 @@ class Meta:
         "Collection's stac_extensions_enabled field.",
     )
 
+    cf_standard_name = models.CharField(
+        null=True,
+        blank=True,
+        max_length=255,
+        help_text="Corresponds to the CF Standard Name from the CF Standard Name Table."
+    )
+
+    unit = models.CharField(
+        null=True, blank=True, max_length=255, help_text="Corresponds to the CF units."
+    )
+
     # Custom Manager that preselects the collection
     objects = ItemManager()
 

app/stac_api/serializers/item.py

@@ -102,6 +102,9 @@ class ItemsPropertiesSerializer(serializers.Serializer):
     forecast_variable = serializers.CharField(required=False, allow_null=True, default=None)
     forecast_perturbed = serializers.BooleanField(required=False, allow_null=True, default=None)
 
+    cf_standard_name = serializers.CharField(required=False, allow_null=True, default=None)
+    unit = serializers.CharField(required=False, allow_null=True, default=None)
+
     def to_internal_value(self, data) -> timedelta:
         '''Map forecast extension fields with a colon in the name to the corresponding model field.
 
@@ -115,6 +118,8 @@ def to_internal_value(self, data) -> timedelta:
             'forecast:duration': 'forecast_duration',
             'forecast:variable': 'forecast_variable',
             'forecast:perturbed': 'forecast_perturbed',
+            'cf:standard_name': 'cf_standard_name',
+            'unit': 'unit',
         }
         data_mapped = copy.deepcopy(data)
         for with_colon, with_underscore in fields.items():
@@ -139,6 +144,8 @@ def to_representation(self, instance):
             'forecast_duration': 'forecast:duration',
             'forecast_variable': 'forecast:variable',
             'forecast_perturbed': 'forecast:perturbed',
+            'cf_standard_name': 'cf:standard_name',
+            'unit': 'unit',
         }
         for with_colon, with_underscore in fields.items():
             if with_colon in ret:

app/stac_api/utils.py

@@ -314,19 +314,22 @@ def harmonize_post_get_for_search(request):
         if 'intersects' in query_param:
             query_param['intersects'] = json.loads(query_param['intersects'])
 
-        # Forecast properties can only be filtered with method POST.
+        # Forecast and CF extension properties can only be filtered with method POST.
         # Decision was made as `:` need to be url encoded and (at least for now) we do not need to
         # support forecast filtering in the GET request.
-        if 'forecast:reference_datetime' in query_param:
-            del query_param['forecast:reference_datetime']
-        if 'forecast:horizon' in query_param:
-            del query_param['forecast:horizon']
-        if 'forecast:duration' in query_param:
-            del query_param['forecast:duration']
-        if 'forecast:variable' in query_param:
-            del query_param['forecast:variable']
-        if 'forecast:perturbed' in query_param:
-            del query_param['forecast:perturbed']
+        forecast_properties = [
+            'forecast:reference_datetime',
+            'forecast:horizon',
+            'forecast:duration',
+            'forecast:variable',
+            'forecast:perturbed'
+        ]
+        cf_properties = ['cf:standard_name', 'unit']
+        properties_to_remove = forecast_properties + cf_properties
+        for p in properties_to_remove:
+            if p in query_param:
+                del query_param[p]
+
     return query_param
 
 

app/stac_api/validators.py

@@ -32,6 +32,7 @@ class StacExtension(TextChoices):
     '''STAC extensions that can be enabled for a Collection and used by its Items.'''
     TIMESTAMPS = 'https://stac-extensions.github.io/timestamps/v1.1.0/schema.json', 'Timestamps'
     FORECAST = 'https://stac-extensions.github.io/forecast/v0.2.0/schema.json', 'Forecast'
+    CF = 'https://stac-extensions.github.io/cf/v1.0.0/schema.json', 'CF'
 
 
 def validate_stac_extensions_enabled(stac_extensions, collection):
@@ -76,6 +77,8 @@ def validate_item_properties_extensions(properties, stac_extensions):
         'forecast:duration': StacExtension.FORECAST,
         'forecast:variable': StacExtension.FORECAST,
         'forecast:perturbed': StacExtension.FORECAST,
+        'cf:standard_name': StacExtension.CF,
+        'unit': StacExtension.CF,
     }
 
     errors = {}

app/stac_api/validators_serializer.py

@@ -70,7 +70,7 @@ def __init__(self):
         # Note: if these values are adapted, don't forget to
         # update the spec accordingly.
         self.queriable_date_fields = ['created', 'updated']
-        self.queriable_str_fields = ['title']
+        self.queriable_str_fields = ['title', 'cf:standard_name', 'unit']
 
     def validate(self, request):
         '''Validates the request of the search endpoint