Fix importer fewer columns than expected Traceback (#160)

Now when an importer spec is modified to have a column
reference that is out of range for the source data, an
error is shown. If such importer spec is executed an
error will also be thrown and logged.

Re spine-tools/Spine-Toolbox#2333

spine_items/importer/mvcmodels/mappings_model.py

@@ -1121,6 +1121,20 @@ def set_filter_re(self, table_row, list_row, row, filter_re):
         index = self.index(row, FlattenedColumn.REGEXP, list_index)
         self.dataChanged.emit(index, index, [Qt.ItemDataRole.DisplayRole])
 
+    def check_validity_of_columns(self, list_index, header):
+        """Checks that the mapping doesn't have column refs
+        that are larger than the source table column count
+
+        Args:
+            list_index (QModelIndex): index to mappings list
+            header (Iterable): source table header
+        Returns:
+            bool: True if no source ref. is out of range, False otherwise
+        """
+        mapping_list_item = list_index.internalPointer()
+        table_name = mapping_list_item.source_table_item.name
+        return mapping_list_item.flattened_mappings.root_mapping.check_for_invalid_column_refs(header, table_name)
+
     @staticmethod
     def polish_mapping(list_index, header):
         """Polishes flattened mappings.

spine_items/importer/widgets/import_sources.py

@@ -37,6 +37,7 @@
     IntegerSequenceDateTimeConvertSpec,
     StringConvertSpec,
 )
+from spinedb_api.exception import InvalidMappingComponent
 from .custom_menus import SourceListMenu, SourceDataTableMenu
 from .mime_types import MAPPING_LIST_MIME_TYPE, TABLE_OPTIONS_MIME_TYPE
 from .options_widget import OptionsWidget
@@ -86,7 +87,7 @@ def __init__(self, mappings_model, ui, undo_stack, parent):
         # connect signals
         self._mappings_model.modelAboutToBeReset.connect(self._store_source_list_current_index)
         self._mappings_model.modelReset.connect(self._restore_source_list_current_index)
-        self._mappings_model.dataChanged.connect(self._update_source_table_colors)
+        self._mappings_model.dataChanged.connect(self._handle_mapping_data_changed)
         self._mappings_model.row_or_column_type_recommended.connect(self._source_data_model.set_type)
         self._mappings_model.multi_column_type_recommended.connect(self._source_data_model.set_all_column_types)
         self._ui_options_widget.options_changed.connect(lambda _: self._clear_source_data_model())
@@ -103,6 +104,20 @@ def __init__(self, mappings_model, ui, undo_stack, parent):
         self._source_data_model.row_types_updated.connect(self._new_row_types)
         self._source_data_model.polish_mapping_requested.connect(self._polish_mappings_in_list)
 
+    @Slot(QModelIndex, QModelIndex, list)
+    def _handle_mapping_data_changed(self, top_left, bottom_right, roles):
+        self._update_source_table_colors(top_left, bottom_right, roles)
+        table_index = self._ui.source_list.selectionModel().currentIndex()
+        if not table_index.isValid() or table_index.row() == 0:
+            return
+        header = self._source_data_model.header
+        for list_row in range(self._mappings_model.rowCount(table_index)):
+            list_index = self._mappings_model.index(list_row, 0, table_index)
+            msg = self._mappings_model.check_validity_of_columns(list_index, header)
+            if msg:
+                self.parent().show_error(msg)
+                return
+
     def set_connector(self, connector, mapping):
         """Sets connector.
 
@@ -141,7 +156,10 @@ def _polish_mappings_in_list(self):
         header = self._source_data_model.header
         for list_row in range(self._mappings_model.rowCount(table_index)):
             list_index = self._mappings_model.index(list_row, 0, table_index)
-            self._mappings_model.polish_mapping(list_index, header)
+            try:
+                self._mappings_model.polish_mapping(list_index, header)
+            except InvalidMappingComponent as error:
+                self.parent().show_error(str(error))
 
     @Slot(str)
     def _select_table_for_undo(self, table_name):
@@ -247,7 +265,6 @@ def _reset_default_column_type(self, table_name):
         self._ui.default_column_type_combo_box.setCurrentText(column_type)
         self._ui.default_column_type_combo_box.currentTextChanged.connect(self._set_default_column_type)
 
-    @Slot(QModelIndex, QModelIndex, list)
     def _update_source_table_colors(self, top_left, bottom_right, roles):
         """Notifies source table model that colors have changed.