PB-2354 Add validation for CF extension property fields

As for the other extensions (see PB-2355, #658), the CF extension needs
to be
- enabled on Collection level (`stac_extensions_enabled`)
- declared on Item level (`stac_extensions`)

Author: asteiner-swisstopo

app/stac_api/serializers/item.py

@@ -406,20 +406,6 @@ class Meta:
     def get_type(self, obj):
         return 'Feature'
 
-    def get_stac_extensions(self, obj):
-        extensions = [
-            # Extension provides schema for the 'expires' timestamp
-            "https://stac-extensions.github.io/timestamps/v1.1.0/schema.json"
-        ]
-        # IMPROVEMENT: This could be improved if there are other extensions coming by
-        # keeping the information on collection object itself
-        if obj.collection.name.startswith('ch.meteoschweiz.ogd-forecasting-icon'):
-            extensions.append("https://stac-extensions.github.io/forecast/v0.2.0/schema.json")
-        # Add CF extension when CF properties are present
-        if obj.cf_standard_name is not None or obj.unit is not None:
-            extensions.append("https://stac-extensions.github.io/cf/v0.2.0/schema.json")
-        return extensions
-
     def get_stac_version(self, obj):
         return get_stac_version(self.context.get('request'))
 

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/tests/tests_09/test_items_endpoint.py

@@ -678,16 +678,14 @@ def test_item_endpoint_patch(self):
         self.assertIn("title", json_data['properties'].keys())
 
     def test_item_endpoint_patch_remove_all_optional_properties(self):
-        # This test uses the expires/forecast:* properties, which requires the timestamps and
-        # forecast extensions to be enabled for the collection.
         self.collection.model.stac_extensions_enabled = [
-            StacExtension.TIMESTAMPS, StacExtension.FORECAST
+            StacExtension.TIMESTAMPS, StacExtension.FORECAST, StacExtension.CF
         ]
         self.collection.model.save()
 
         # First add all properties
         data = {
-            "stac_extensions": [StacExtension.TIMESTAMPS, StacExtension.FORECAST],
+            "stac_extensions": [StacExtension.TIMESTAMPS, StacExtension.FORECAST, StacExtension.CF],
             "properties": {
                 "title": "patched title",
                 "expires": "2060-02-12T23:20:50Z",

app/tests/tests_10/test_items_endpoint.py

@@ -814,16 +814,14 @@ def test_item_endpoint_patch(self):
         self.assertIn("title", json_data['properties'].keys())
 
     def test_item_endpoint_patch_remove_all_optional_properties(self):
-        # This test uses the expires/forecast:* properties, which requires the timestamps and
-        # forecast extensions to be enabled for the collection.
         self.collection.model.stac_extensions_enabled = [
-            StacExtension.TIMESTAMPS, StacExtension.FORECAST
+            StacExtension.TIMESTAMPS, StacExtension.FORECAST, StacExtension.CF
         ]
         self.collection.model.save()
 
         # First add all properties
         data = {
-            "stac_extensions": [StacExtension.TIMESTAMPS, StacExtension.FORECAST],
+            "stac_extensions": [StacExtension.TIMESTAMPS, StacExtension.FORECAST, StacExtension.CF],
             "properties": {
                 "title": "patched title",
                 "expires": "2060-02-12T23:20:50Z",