def get_database_definition(
self: T, sess: Session, dependencies: Optional[List["ReplaceableEntity"]] = None
) -> T: # $Optional[T]:
"""Creates the entity in the database, retrieves its 'rendered' then rolls it back"""
with simulate_entity(sess, self, dependencies) as sess:
# Drop self
sess.execute(self.to_sql_statement_drop())
# collect all remaining entities
db_entities: List[T] = sorted(
self.from_database(sess, schema=self.schema), key=lambda x: x.identity
)
with simulate_entity(sess, self, dependencies) as sess:
# collect all remaining entities
all_w_self: List[T] = sorted(
self.from_database(sess, schema=self.schema), key=lambda x: x.identity
)
# Find "self" by diffing the before and after
for without_self, with_self in zip_longest(db_entities, all_w_self):
if without_self is None or without_self.identity != with_self.identity:
return with_self
raise UnreachableException()
def solve_resolution_order(sess: Session, entities):
"""Solve for an entity resolution order that increases the probability that
a migration will suceed if, for example, two new views are created and one
refers to the other
This strategy will only solve for simple cases
"""
resolved = []
# Resolve the entities with 0 dependencies first (faster)
logger.info("Resolving entities with no dependencies")
for entity in entities:
try:
with simulate_entity(sess, entity):
resolved.append(entity)
except (sqla_exc.ProgrammingError, sqla_exc.InternalError) as exc:
continue
# Resolve entities with possible dependencies
for _ in range(len(entities)):
logger.info(
"Resolving entities with dependencies. This may take a minute")
n_resolved = len(resolved)
for entity in entities:
if entity in resolved:
continue
try:
with simulate_entity(sess, entity, dependencies=resolved):
resolved.append(entity)
except (sqla_exc.ProgrammingError, sqla_exc.InternalError):
continue
if len(resolved) == n_resolved:
# No new entities resolved in the last iteration. Exit
break
for entity in entities:
if entity not in resolved:
resolved.append(entity)
return resolved
def test_simulate_entity_shows_user_code_error(sess: Session) -> None:
sess.execute(TEST_VIEW.to_sql_statement_create())
with pytest.raises(DataError):
with simulate_entity(sess, TEST_VIEW):
# Raises a sql error
sess.execute("select 1/0").fetchone()
# Confirm context manager exited gracefully
assert True