fix: correct get_metadata return annotations

pandera/api/dataframe/container.py

@@ -262,7 +262,7 @@ def dtypes(self) -> dict[str, DataType]:
             )
         return {n: c.dtype for n, c in self.columns.items() if not c.regex}
 
-    def get_metadata(self) -> dict | None:
+    def get_metadata(self) -> dict[Any, Any]:
         """Provide metadata for columns and schema level"""
         res: dict[Any, Any] = {"columns": {}}
         for k in self.columns.keys():

pandera/api/dataframe/model.py

@@ -630,7 +630,7 @@ def _extract_df_parsers(
         return [parser_info.to_parser(cls) for parser_info in parser_infos]
 
     @classmethod
-    def get_metadata(cls) -> dict | None:
+    def get_metadata(cls) -> dict[Any, Any]:
         """Provide metadata for columns and schema level"""
         res: dict[Any, Any] = {"columns": {}}
         columns = cls._collect_fields()

tests/mypy/pandas_modules/pandera_metadata.py

@@ -0,0 +1,15 @@
+# pylint: skip-file
+from typing import Any
+
+import pandera.pandas as pa
+
+
+class Foo(pa.DataFrameModel):
+    x: int
+
+
+model_metadata: dict[Any, Any] = Foo.get_metadata()
+model_value = model_metadata[str(Foo)]
+
+schema = Foo.to_schema()
+schema_metadata: dict[Any, Any] = schema.get_metadata()

tests/mypy/test_pandas_static_type_checking.py

@@ -180,6 +180,7 @@ def test_pandera_runtime_errors(fn) -> None:
         ["pandera_types.py", "plugin_mypy.ini", []],
         ["pandas_concat.py", "no_plugin.ini", []],
         ["pandas_concat.py", "plugin_mypy.ini", []],
+        ["pandera_metadata.py", "no_plugin.ini", []],
         ["pandas_time.py", "no_plugin.ini", PANDAS_TIME_ERRORS],
         ["pandas_time.py", "plugin_mypy.ini", PANDAS_TIME_ERRORS],
         ["python_slice.py", "no_plugin.ini", PYTHON_SLICE_ERRORS],
@@ -292,6 +293,7 @@ def test_pandas_stubs_false_positives(
         "pandera_inheritance",
         "pandera_types",
         "pandas_concat",
+        "pandera_metadata",
         "pandas_time",
         "python_slice",
         "pandas_index",