fix: let nested keys override non-mapping values in build_dict (#215)

confuse/util.py

@@ -112,7 +112,7 @@ def build_dict(
                         save_to = save_to[child_key]
 
         # Save
-        if key in save_to:
+        if isinstance(save_to.get(key), dict) and isinstance(result, dict):
             save_to[key].update(result)
         else:
             save_to[key] = result

docs/changelog.rst

@@ -13,9 +13,12 @@ Unreleased
     New features
     ~~~~~~~~~~~~
 
-..
-    Bug fixes
-    ~~~~~~~~~
+Bug fixes
+~~~~~~~~~
+
+- A more specific nested key (for example ``APP_DATABASE__PORT`` or a dotted
+  ``set_args`` key) no longer raises when it overrides a non-mapping value
+  inside an existing mapping; the more specific value now wins.
 
 ..
     For plugin developers

test/test_env.py

@@ -182,6 +182,12 @@ def test_parse_yaml_docs_scalar(self):
         config = _root(confuse.EnvSource("TEST_", parse_yaml_docs=True))
         assert config["foo"].get() == "a"
 
+    def test_nested_env_var_overrides_yaml_mapping_leaf(self):
+        os.environ["TEST_DATABASE"] = "{host: localhost, port: 5432}"
+        os.environ["TEST_DATABASE__PORT"] = "5433"
+        config = _root(confuse.EnvSource("TEST_", parse_yaml_docs=True))
+        assert {"host": "localhost", "port": 5433} == config["database"].get(dict)
+
     def test_parse_yaml_docs_list(self):
         os.environ["TEST_FOO"] = "[a, b]"
         config = _root(confuse.EnvSource("TEST_", parse_yaml_docs=True))

test/test_utils.py

@@ -54,6 +54,19 @@ def test_dot_sep_keys_no_clobber(self):
         assert 2 == result["foo"]["far"]
         assert 4 == result["foo"]["zar"]["dar"]
 
+    def test_nested_key_overrides_scalar_in_existing_mapping(self):
+        config = {
+            "database": {"host": "localhost", "port": 5432},
+            "database.port": 5433,
+        }
+        result = confuse.util.build_dict(config, sep=".")
+        assert {"host": "localhost", "port": 5433} == result["database"]
+
+    def test_nested_key_overrides_list_in_existing_mapping(self):
+        config = {"foo": {"bar": [1, 2]}, "foo.bar": 3}
+        result = confuse.util.build_dict(config, sep=".")
+        assert 3 == result["foo"]["bar"]
+
     def test_adjacent_underscores_sep_keys(self):
         config: dict[str, Any] = {"foo__bar_baz": 1}
         result = confuse.util.build_dict(config.copy())