feat: improved alias resolvers (#1181)

- added support for resolving trivial nested fields

ariadne/resolvers.py

@@ -79,9 +79,16 @@ def add_resolver_to_field(
 
 
 def resolve_parent_field(parent: Any, field_name: str) -> Any:
-    if isinstance(parent, Mapping):
-        return parent.get(field_name)
-    return getattr(parent, field_name, None)
+    value = parent
+    for name in field_name.split("."):
+        if isinstance(value, Mapping):
+            value = value.get(name)
+        else:
+            value = getattr(value, name, None)
+
+        if value is None:
+            break
+    return value
 
 
 def resolve_to(attr_name: str) -> Resolver:

tests/test_default_resolvers.py

@@ -14,6 +14,15 @@ def callable_resolver(*_):
     assert alias_resolver(obj, None)
 
 
+def test_alias_resolver_supports_nested_name():
+    parent_mapping = {"nested": {"hello": "world"}}
+    parent_object = Mock(nested=Mock(hello="world"))
+
+    alias_resolver = resolve_to("nested.hello")
+    assert alias_resolver(parent_mapping, None) == "world"
+    assert alias_resolver(parent_object, None) == "world"
+
+
 def test_alias_resolver_passess_field_args_to_callable_return_value():
     def callable_resolver(*_, test):
         return test