FIX: Foreign key specification when generating XLSX templates.

src/caosadvancedtools/table_json_conversion/table_generator.py

@@ -71,6 +71,11 @@ class TableTemplateGenerator(ABC):
 
             Example: ``{"Training": {"__this__": ["date"], "Person": ["name", "email"]}}``
             Here, ``date`` is the sole foreign key for Training.
+
+            | It probably is worth extending the first example, with a case where a "Training" shall
+              be distiguished by the "name" and "email" of a "Person" which it references.  The
+              foreign keys for this example are specified like this:
+            | ``{"Training": {"__this__": [["Person", "name"], ["Person", "email"]]}}``
         """
 
     def _generate_sheets_from_schema(self, schema: dict, foreign_keys: Optional[dict] = None
@@ -121,7 +126,13 @@ class TableTemplateGenerator(ABC):
         return sheets
 
     def _get_foreign_keys(self, keys: dict, path: list) -> list:
-        """Return the foreign keys that are needed at the location to which path points."""
+        """Return the foreign keys that are needed at the location to which path points.
+
+Returns
+-------
+foreign_keys: list
+  Contains strings or lists of strings.
+"""
         msg = f"A foreign key definition is missing for path:\n{path}\nKeys are:\n{keys}"
         while path:
             if keys is None or path[0] not in keys:
@@ -198,14 +209,17 @@ class TableTemplateGenerator(ABC):
                                              "string was given:\n"
                                              f"{array_path} -> {foreigns}")
                         for foreign in foreigns:
-                            internal_key = p2s(array_path + [foreign])
+                            if isinstance(foreign, str):
+                                foreign = [foreign]
+                            internal_key = p2s(array_path + foreign)
                             if internal_key in sheets[sheetname]:
-                                raise ValueError("The schema would lead to two columns with the same "
-                                                 "name, which is forbidden:\n"
+                                raise ValueError("The schema would lead to two columns with the "
+                                                 "same name, which is forbidden:\n"
                                                  f"{foreign} -> {internal_key}")
                             ref_sheet = p2s(array_path)
                             sheets[sheetname][internal_key] = (
-                                ColumnType.FOREIGN, f"see sheet '{ref_sheet}'", array_path + [foreign])
+                                ColumnType.FOREIGN, f"see sheet '{ref_sheet}'",
+                                array_path + foreign)
                 # Columns are added to the new sheet, thus we do not return any columns for the
                 # current sheet.
                 return {}
@@ -301,7 +315,7 @@ class XLSXTemplateGenerator(TableTemplateGenerator):
         definition dict
         You need to pass the dict of a single sheet to this function.
         """
-        return max([len(path) for _, _, path in sheetdef.values()])
+        return max(len(path) for _, _, path in sheetdef.values())
 
     @staticmethod
     def _get_ordered_cols(sheetdef: dict) -> list:

unittests/table_json_conversion/test_table_template_generator.py

@@ -263,7 +263,7 @@ def test_model_with_indirect_reference():
     _compare_generated_to_known_good(
         schema_file=rfp("data/indirect_schema.json"),
         known_good=rfp("data/indirect_template.xlsx"),
-        foreign_keys={"Wrapper": ["Training.name", "Training.url"]},
+        foreign_keys={"Wrapper": {"__this__": [["Training", "name"], ["Training", "url"]]}},
         outfile=None)