Fix filters on nested provider/aliased fields

optimade/server/mappers/entries.py

@@ -88,7 +88,11 @@ def alias_for(cls, field: str) -> str:
         :return: Aliased field as found in PROVIDER_ALIASES + ALIASES
         :rtype: str
         """
-        return dict(cls.all_aliases()).get(field, field)
+        split = field.split(".")
+        alias = dict(cls.all_aliases()).get(split[0], None)
+        if alias is not None:
+            return alias + ("." + ".".join(split[1:]) if len(split) > 1 else "")
+        return field
 
     @classmethod
     def get_required_fields(cls) -> set:

tests/filtertransformers/test_mongo.py

@@ -540,6 +540,7 @@ class MyStructureMapper(BaseResourceMapper):
                 ("A", "D"),
                 ("B", "E"),
                 ("C", "F"),
+                ("_exmpl_nested_field", "nested_field"),
             )
 
         mapper = MyStructureMapper()
@@ -564,6 +565,17 @@ class MyStructureMapper(BaseResourceMapper):
         test_filter = ["A", "elements", "C"]
         self.assertEqual(t.postprocess(test_filter), ["A", "elements", "C"])
 
+        test_filter = {"_exmpl_nested_field.sub_property": {"$gt": 1234.5}}
+        self.assertEqual(
+            t.postprocess(test_filter), {"nested_field.sub_property": {"$gt": 1234.5}}
+        )
+
+        test_filter = {"_exmpl_nested_field.sub_property.x": {"$exists": False}}
+        self.assertEqual(
+            t.postprocess(test_filter),
+            {"nested_field.sub_property.x": {"$exists": False}},
+        )
+
     def test_list_properties(self):
         """ Test the HAS ALL, ANY and optional ONLY queries.
 

tests/server/test_mappers.py

@@ -16,3 +16,36 @@ class MyMapper(BaseResourceMapper):
         toy_collection = mongomock.MongoClient()["fake"]["fake"]
         with self.assertRaises(RuntimeError):
             MongoCollection(toy_collection, StructureResource, mapper)
+
+    def test_property_aliases(self):
+        class MyMapper(BaseResourceMapper):
+            PROVIDER_FIELDS = ("dft_parameters", "test_field")
+            LENGTH_ALIASES = (("_exmpl_test_field", "test_field_len"),)
+            ALIASES = (("field", "completely_different_field"),)
+
+        mapper = MyMapper()
+        self.assertEqual(mapper.alias_for("_exmpl_dft_parameters"), "dft_parameters")
+        self.assertEqual(mapper.alias_for("_exmpl_test_field"), "test_field")
+        self.assertEqual(mapper.alias_for("field"), "completely_different_field")
+        self.assertEqual(mapper.length_alias_for("_exmpl_test_field"), "test_field_len")
+        self.assertEqual(mapper.length_alias_for("test_field"), None)
+        self.assertEqual(mapper.alias_for("test_field"), "test_field")
+
+        # nested properties
+        self.assertEqual(
+            mapper.alias_for("_exmpl_dft_parameters.nested.property"),
+            "dft_parameters.nested.property",
+        )
+        self.assertEqual(
+            mapper.alias_for("_exmpl_dft_parameters.nested_property"),
+            "dft_parameters.nested_property",
+        )
+
+        # test nonsensical query
+        self.assertEqual(mapper.alias_for("_exmpl_test_field."), "test_field.")
+
+        # test an awkward case that has no alias
+        self.assertEqual(
+            mapper.alias_for("_exmpl_dft_parameters_dft_parameters.nested.property"),
+            "_exmpl_dft_parameters_dft_parameters.nested.property",
+        )