Give RuntimeWarning if stored function calls use pandas object arguments (#310)

Author: anders-kiaer

CHANGELOG.md

@@ -10,6 +10,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - [#311](https://github.com/equinor/webviz-config/pull/311) - Automatically add a comment
 in generated application regarding which Python executable (`sys.executable`) was used
 when building a portable application.
+- [#310](https://github.com/equinor/webviz-config/pull/310) - Added `RuntimeWarning`
+which appears if `@webvizstore` decorated functions are given argument values of type
+`pandas.DataFrame` or `pandas.Series` (Which are known to not have `__repr__` functions
+useful for hashing).
 
 ### Fixed
 - [#313](https://github.com/equinor/webviz-config/pull/313) - Added `min-width` to menu CSS

webviz_config/webviz_store.py

@@ -5,6 +5,7 @@
 import hashlib
 import inspect
 import pathlib
+import warnings
 from collections import defaultdict
 from typing import Callable, List, Union, Any
 
@@ -72,6 +73,24 @@ def register_function_arguments(self, functionarguments: List[tuple]) -> None:
                         repr(argtuples)
                     ] = argtuples
 
+                for (argname, argvalue) in argtuples:
+                    # Check that values of decorated functions are not pandas objects.
+                    # This function could probably at some point be moved into a pytest
+                    # fixture (given that plugins use type hints) in order to slightly
+                    # reduce running time.
+                    if isinstance(argvalue, (pd.DataFrame, pd.Series)):
+                        warnings.warn(
+                            f"{func.__module__}.{func.__name__} is a @webvizstore decorated "
+                            f"function, and argument {argname} has been given a pandas "
+                            "object as value. Since pandas.DataFrames and pandas.Series are "
+                            "known to not have unique/deterministic __repr__ functions, "
+                            "they do not work well with @webvizstore (or flask-caching). "
+                            "Consider moving to another object with a deterministic "
+                            "__repr__ representation more suitable for hashing.",
+                            RuntimeWarning,
+                            stacklevel=0,
+                        )
+
     def _unique_path(self, func: Callable, argtuples: tuple) -> str:
         """Encodes the argumenttuples as bytes, and then does a sha256 on that.
         Mutable arguments are accepted in the argument tuples, however it is