Management Empty sets

[dachafra]

The Test-case R2RMLTC0000 tests an empty database with a valid schema, morph-kgc fails bc it tries to find answers.

Mapping and result: https://github.com/kg-construct/r2rml-implementation-report/tree/main/test-cases/R2RMLTC0000
Database: https://github.com/kg-construct/r2rml-implementation-report/blob/main/test-cases/databases/d000.sql

Log:

Traceback (most recent call last):
  File "/Users/dchaves/anaconda3/lib/python3.7/site-packages/pandas/core/indexes/base.py", line 2895, in get_loc
    return self._engine.get_loc(casted_key)
  File "pandas/_libs/index.pyx", line 70, in pandas._libs.index.IndexEngine.get_loc
  File "pandas/_libs/index.pyx", line 101, in pandas._libs.index.IndexEngine.get_loc
  File "pandas/_libs/hashtable_class_helper.pxi", line 1675, in pandas._libs.hashtable.PyObjectHashTable.get_item
  File "pandas/_libs/hashtable_class_helper.pxi", line 1683, in pandas._libs.hashtable.PyObjectHashTable.get_item
KeyError: '"Name"'
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
  File "morph-kgc/semantify.py", line 25, in <module>
    materialize(mappings_df, config)
  File "/Users/dchaves/Downloads/morph-kgc/r2rml-implementation-report/test-cases/morph-kgc/materializer.py", line 274, in materialize
    result_triples = _materialize_mapping_rule(mapping_rule, subject_maps_df, config)
  File "/Users/dchaves/Downloads/morph-kgc/r2rml-implementation-report/test-cases/morph-kgc/materializer.py", line 230, in _materialize_mapping_rule
    query_results_df = _materialize_template(query_results_df, mapping_rule['subject_template'], termtype=mapping_rule['subject_termtype'])
  File "/Users/dchaves/Downloads/morph-kgc/r2rml-implementation-report/test-cases/morph-kgc/materializer.py", line 61, in _materialize_template
    query_results_df['reference_results'] = query_results_df[columns_alias + reference]
  File "/Users/dchaves/anaconda3/lib/python3.7/site-packages/pandas/core/frame.py", line 2906, in _getitem_
    indexer = self.columns.get_loc(key)
  File "/Users/dchaves/anaconda3/lib/python3.7/site-packages/pandas/core/indexes/base.py", line 2897, in get_loc
    raise KeyError(key) from err
KeyError: '"Name"'

[arenas-guerrero-julian]

Solved is already solved and motph passes the test case R2RMLTC0000.