def guard(fn):
"""Decorator function that converts sqlite exceptions into weedb exceptions."""
def guarded_fn(*args, **kwargs):
try:
return fn(*args, **kwargs)
except sqlite3.IntegrityError, e:
raise weedb.IntegrityError(e)
except sqlite3.OperationalError, e:
msg = str(e).lower()
if msg.startswith("unable to open"):
raise weedb.PermissionError(e)
elif msg.startswith("no such table"):
raise weedb.NoTableError(e)
elif msg.endswith("already exists"):
raise weedb.TableExistsError(e)
elif msg.startswith("no such column"):
raise weedb.NoColumnError(e)
else:
raise weedb.OperationalError(e)
def guarded_fn(*args, **kwargs):
try:
return fn(*args, **kwargs)
except sqlite3.IntegrityError as e:
raise weedb.IntegrityError(e)
except sqlite3.OperationalError as e:
msg = str(e).lower()
if msg.startswith("unable to open"):
raise weedb.PermissionError(e)
elif msg.startswith("no such table"):
raise weedb.NoTableError(e)
elif msg.endswith("already exists"):
raise weedb.TableExistsError(e)
elif msg.startswith("no such column"):
raise weedb.NoColumnError(e)
else:
raise weedb.OperationalError(e)
except sqlite3.ProgrammingError as e:
raise weedb.ProgrammingError(e)
def drop_columns(self, table, column_names):
"""Drop the set of 'column_names' from table 'table'.
table: The name of the table from which the column(s) are to be dropped.
column_names: A set (or list) of column names to be dropped. It is not an error to try to
drop a non-existent column.
"""
existing_column_set = set()
create_list = []
insert_list = []
self.execute("""PRAGMA table_info(%s);""" % table)
for row in self.fetchall():
# Unpack the row
row_no, obs_name, obs_type, no_null, default, pk = row
existing_column_set.add(obs_name)
# Search through the target columns.
if obs_name in column_names:
continue
no_null_str = " NOT NULL" if no_null else ""
pk_str = " UNIQUE PRIMARY KEY" if pk else ""
default_str = " DEFAULT %s" % default if default is not None else ""
create_list.append("`%s` %s%s%s%s" % (obs_name, obs_type, no_null_str,
pk_str, default_str))
insert_list.append(obs_name)
for column in column_names:
if column not in existing_column_set:
raise weedb.NoColumnError("Cannot DROP '%s'; column does not exist." % column)
create_str = ", ".join(create_list)
insert_str = ", ".join(insert_list)
self.execute("CREATE TEMPORARY TABLE %s_temp (%s);" % (table, create_str))
self.execute("INSERT INTO %s_temp SELECT %s FROM %s;" % (table, insert_str, table))
self.execute("DROP TABLE %s;" % table)
self.execute("CREATE TABLE %s (%s);" % (table, create_str))
self.execute("INSERT INTO %s SELECT %s FROM %s_temp;" % (table, insert_str, table))
self.execute("DROP TABLE %s_temp;" % table)