refs #281, Sorting by foreign keys

Sorting for foreign keys works again.  A temporary column is added that maps the fk to the description column of the parent table, the dataset is sorted on this temporary column, then the temporary column is dropped in place.

Author: PySimpleSQL

pysimplesql/pysimplesql.py

@@ -2206,13 +2206,15 @@ def sort_by_column(self, column: str, table: str, reverse=False) -> None:
         rels = Relationship.get_relationships(table)
         for rel in rels:
             if column == rel.fk_column:
-                # change the rows used for sort criteria
-                rel.frm[rel.parent_table]
-
-                # change our target column to look in
-
-                # and return the value in this column
-                rel.frm[rel.parent_table].description_column
+                # Create a mapping dictionary from the parent DataFrame
+                df_parent = self.frm[rel.parent_table].rows
+                desc_parent = self.frm[rel.parent_table].description_column
+                mapping = dict(zip(df_parent[rel.pk_column], df_parent[desc_parent]))
+
+                # Create a temporary column in self.rows for the fk data
+                tmp = f"temp_{rel.parent_table}.{rel.pk_column}"
+                self.rows[tmp] = self.rows[rel.fk_column].map(mapping)
+                column = tmp
                 break
         try:
             self.rows.sort_values(
@@ -2222,6 +2224,9 @@ def sort_by_column(self, column: str, table: str, reverse=False) -> None:
             )
         except KeyError:
             logger.debug(f"DataFrame could not sort by column {column}. KeyError.")
+        finally:
+            # Drop the temporary description column (if it exists)
+            self.rows.drop(columns=tmp, inplace=True, errors="ignore")
 
     def sort_by_index(self, index: int, table: str, reverse=False):
         """