def _handle_alias(self, alias_info, dialect, queries):
select_info_target = SelectCrawler.get(
alias_info.from_expression_element, queries, dialect)
if isinstance(select_info_target, str):
# It's an alias to an external table whose
# number of columns could vary without our
# knowledge. Thus, warn.
self.logger.debug(
f"Query target {select_info_target} is external. Generating warning."
)
raise RuleFailure()
else:
# Handle nested SELECT.
self._analyze_result_columns(select_info_target, dialect, queries)
def _analyze_result_columns(
self,
select_info_list: List[SelectCrawler],
dialect: Dialect,
queries: Dict[str, List[SelectCrawler]],
):
"""Given info on a list of SELECTs, determine whether to warn."""
# Recursively walk from the given query (select_info_list) to any
# wildcard columns in the select targets. If every wildcard evdentually
# resolves to a query without wildcards, all is well. Otherwise, warn.
for select_info in select_info_list:
self.logger.debug(
f"Analyzing query: {select_info.select_statement.raw}")
for wildcard in select_info.get_wildcard_info():
if wildcard.tables:
for wildcard_table in wildcard.tables:
self.logger.debug(
f"Wildcard: {wildcard.segment.raw} has target {wildcard_table}"
)
# Is it an alias?
alias_info = select_info.find_alias(wildcard_table)
if alias_info:
# Found the alias matching the wildcard. Recurse,
# analyzing the query associated with that alias.
self._handle_alias(alias_info, dialect, queries)
else:
# Not an alias. Is it a CTE?
if wildcard_table in queries:
# Wildcard refers to a CTE. Analyze it.
self._analyze_result_columns(
queries.pop(wildcard_table), dialect,
queries)
else:
# Not CTE, not table alias. Presumably an
# external table. Warn.
self.logger.debug(
f"Query target {wildcard_table} is external. Generating warning."
)
raise RuleFailure()
else:
# No table was specified with the wildcard. Assume we're
# querying from a nested select in FROM.
select_info_target = SelectCrawler.get(
select_info.select_statement, queries, dialect)
assert isinstance(select_info_target, list)
self._analyze_result_columns(
select_info_target,
dialect,
queries,
)
def _analyze_result_columns(self, query: Query):
"""Given info on a list of SELECTs, determine whether to warn."""
# Recursively walk from the given query (select_info_list) to any
# wildcard columns in the select targets. If every wildcard evdentually
# resolves to a query without wildcards, all is well. Otherwise, warn.
if not query.selectables:
return
for selectable in query.selectables:
self.logger.debug(f"Analyzing query: {selectable.selectable.raw}")
for wildcard in selectable.get_wildcard_info():
if wildcard.tables:
for wildcard_table in wildcard.tables:
self.logger.debug(
f"Wildcard: {wildcard.segment.raw} has target "
"{wildcard_table}")
# Is it an alias?
alias_info = selectable.find_alias(wildcard_table)
if alias_info:
# Found the alias matching the wildcard. Recurse,
# analyzing the query associated with that alias.
self._handle_alias(selectable, alias_info, query)
else:
# Not an alias. Is it a CTE?
cte = query.lookup_cte(wildcard_table)
if cte:
# Wildcard refers to a CTE. Analyze it.
self._analyze_result_columns(cte)
else:
# Not CTE, not table alias. Presumably an
# external table. Warn.
self.logger.debug(
f"Query target {wildcard_table} is external. "
"Generating warning.")
raise RuleFailure(selectable.selectable)
else:
# No table was specified with the wildcard. Assume we're
# querying from a nested select in FROM.
query_list = SelectCrawler.get(
query, query.selectables[0].selectable)
for o in query_list:
if isinstance(o, Query):
self._analyze_result_columns(o)
return
self.logger.debug(
f'Query target "{query.selectables[0].selectable.raw}" has no '
"targets. Generating warning.")
raise RuleFailure(query.selectables[0].selectable)