Introduce validator to raise ModuleNotFoundError at dashboard creation (

#97)

Signed-off-by: Maximilian Schulz <[email protected]>
Co-authored-by: Antony Milne <[email protected]>

vizro-core/changelog.d/20231005_145819_maximilian_schulz_86_absence_of_openpyxl_library_causes_console_errors.md

@@ -0,0 +1,41 @@
+<!--
+A new scriv changelog fragment.
+
+Uncomment the section that is right (remove the HTML comment wrapper).
+-->
+
+<!--
+### Removed
+
+- A bullet item for the Removed category.
+
+-->
+
+### Added
+
+- Raise `ModuleNotFoundError` in case the `export_data` action is used with `file_format="xlsx"` and neither `openpyxl` nor `xlsxwriter` are installed ([#97](https://github.com/mckinsey/vizro/pull/97))
+
+<!--
+### Changed
+
+- A bullet item for the Changed category.
+
+-->
+<!--
+### Deprecated
+
+- A bullet item for the Deprecated category.
+
+-->
+<!--
+### Fixed
+
+- A bullet item for the Fixed category.
+
+-->
+<!--
+### Security
+
+- A bullet item for the Security category.
+
+-->

vizro-core/src/vizro/actions/export_data_action.py

@@ -55,8 +55,7 @@ def export_data(
             writer = data_frames[target_id].to_csv
         elif file_format == "xlsx":
             writer = data_frames[target_id].to_excel
-        else:
-            raise ValueError(f'Unknown "file_format": {file_format}.' f' Known file formats: "csv", "xlsx".')
+        # Invalid file_format should be caught by Action validation
 
         callback_outputs[f"download-dataframe_{target_id}"] = dcc.send_data_frame(
             writer=writer, filename=f"{target_id}.{file_format}", index=False

vizro-core/src/vizro/models/_action/_action.py

@@ -1,8 +1,9 @@
+import importlib.util
 import logging
 from typing import Any, Dict, List
 
 from dash import Input, Output, State, callback, ctx
-from pydantic import Field
+from pydantic import Field, validator
 
 import vizro.actions
 from vizro.models import VizroBaseModel
@@ -35,6 +36,24 @@ class Action(VizroBaseModel):
         regex="^[a-zA-Z0-9_]+[.][a-zA-Z_]+$",
     )
 
+    # TODO: Problem: generic Action model shouldn't depend on details of particular actions like export_data.
+    # Possible solutions: make a generic mapping of action functions to validation functions or the imports they
+    # require, and make the code here look up the appropriate validation using the function as key
+    # This could then also involve other validations currently only carried out at run-time in pre-defined actions, such
+    # as e.g. checking if the correct arguments have been provided to the file_format in export_data.
+    @validator("function")
+    def validate_predefined_actions(cls, function):
+        if function._function.__name__ == "export_data":
+            file_format = function._arguments.get("file_format")
+            if file_format not in [None, "csv", "xlsx"]:
+                raise ValueError(f'Unknown "file_format": {file_format}.' f' Known file formats: "csv", "xlsx".')
+            if file_format == "xlsx":
+                if importlib.util.find_spec("openpyxl") is None and importlib.util.find_spec("xlsxwriter") is None:
+                    raise ModuleNotFoundError(
+                        "You must install either openpyxl or xlsxwriter to export to xlsx format."
+                    )
+        return function
+
     @_log_call
     def build(self):
         from vizro.actions._callback_mapping._get_action_callback_mapping import _get_action_callback_mapping

vizro-core/src/vizro/models/types.py

@@ -68,8 +68,8 @@ def __delitem__(self, arg_name: str):
 
     @property
     def _arguments(self):
-        # TODO: This is only used once in _get_parametrized_config and should be removed when that reference is
-        #  removed.
+        # TODO: This is used twice: in _get_parametrized_config and in vm.Action and should be removed when those
+        # references are removed.
         return self.__bound_arguments.arguments
 
     @classmethod

vizro-core/tests/unit/vizro/actions/test_export_data_action.py

@@ -215,28 +215,3 @@ def test_multiple_targets_with_filter_and_filter_interaction(
 
         assert result["download-dataframe_box_chart"]["filename"] == "box_chart.csv"
         assert result["download-dataframe_box_chart"]["content"] == target_box_filtered_pop.to_csv(index=False)
-
-    @pytest.mark.usefixtures("managers_one_page_two_graphs_one_button")
-    @pytest.mark.parametrize(
-        "callback_context_export_data", [(["scatter_chart", "box_chart"], None, None)], indirect=True
-    )
-    def test_invalid_file_format(
-        self,
-        callback_context_export_data,
-    ):
-        # Add action to relevant component
-        model_manager["button"].actions = [
-            vm.Action(
-                id="test_action",
-                function=export_data(
-                    targets=["scatter_chart", "box_chart"],
-                    file_format="invalid_file_format",
-                ),
-            )
-        ]
-
-        with pytest.raises(
-            ValueError, match='Unknown "file_format": invalid_file_format.' ' Known file formats: "csv", "xlsx".'
-        ):
-            # Run action by picking the above added action function and executing it with ()
-            model_manager["test_action"].function()