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import logging
import traceback
from django.db.models.fields import NOT_PROVIDED
from django.db import connection, DatabaseError, backend, models
from django.core.management.color import no_style
from django.core.management.sql import sql_create
import django.core.management
import Bcfg2.settings
logger = logging.getLogger(__name__)
def _quote(value):
"""
Quote a string to use as a table name or column
"""
return backend.DatabaseOperations().quote_name(value)
def _rebuild_sqlite_table(model):
"""Sqlite doesn't support most alter table statments. This streamlines the
rebuild process"""
try:
cursor = connection.cursor()
table_name = model._meta.db_table
# Build create staement from django
model._meta.db_table = "%s_temp" % table_name
sql, references = connection.creation.sql_create_model(model, no_style())
columns = ",".join([_quote(f.column) \
for f in model._meta.fields])
# Create a temp table
[cursor.execute(s) for s in sql]
# Fill the table
tbl_name = _quote(table_name)
tmp_tbl_name = _quote(model._meta.db_table)
# Reset this
model._meta.db_table = table_name
cursor.execute("insert into %s(%s) select %s from %s;" % (
tmp_tbl_name,
columns,
columns,
tbl_name))
cursor.execute("drop table %s" % tbl_name)
# Call syncdb to create the table again
django.core.management.call_command("syncdb", interactive=False, verbosity=0)
# syncdb closes our cursor
cursor = connection.cursor()
# Repopulate
cursor.execute('insert into %s(%s) select %s from %s;' % (tbl_name,
columns,
columns,
tmp_tbl_name))
cursor.execute('DROP TABLE %s;' % tmp_tbl_name)
except DatabaseError:
logger.error("Failed to rebuild sqlite table %s" % table_name, exc_info=1)
raise UpdaterRoutineException
class UpdaterRoutineException(Exception):
pass
class UpdaterRoutine(object):
"""Base for routines."""
def __init__(self):
pass
def __str__(self):
return __name__
def run(self):
"""Called to execute the action"""
raise UpdaterRoutineException
class AddColumns(UpdaterRoutine):
"""
Routine to add new columns to an existing model
"""
def __init__(self, model):
self.model = model
self.model_name = model.__name__
def __str__(self):
return "Add new columns for model %s" % self.model_name
def run(self):
try:
cursor = connection.cursor()
except DatabaseError:
logger.error("Failed to connect to the db")
raise UpdaterRoutineException
try:
desc = {}
for d in connection.introspection.get_table_description(cursor,
self.model._meta.db_table):
desc[d[0]] = d
except DatabaseError:
logger.error("Failed to get table description", exc_info=1)
raise UpdaterRoutineException
for field in self.model._meta.fields:
if field.column in desc:
continue
logger.debug("Column %s does not exist yet" % field.column)
if field.default == NOT_PROVIDED:
logger.error("Cannot add a column with out a default value")
raise UpdaterRoutineException
sql = "ALTER TABLE %s ADD %s %s NOT NULL DEFAULT " % (
_quote(self.model._meta.db_table),
_quote(field.column), field.db_type(), )
db_engine = Bcfg2.settings.DATABASES['default']['ENGINE']
if db_engine == 'django.db.backends.sqlite3':
sql += _quote(field.default)
sql_values = ()
else:
sql += '%s'
sql_values = (field.default, )
try:
cursor.execute(sql, sql_values)
logger.debug("Added column %s to %s" %
(field.column, self.model._meta.db_table))
except DatabaseError:
logger.error("Unable to add column %s" % field.column)
raise UpdaterRoutineException
class RebuildTable(UpdaterRoutine):
"""
Rebuild the table for an existing model. Use this if field types have changed.
"""
def __init__(self, model, columns):
self.model = model
self.model_name = model.__name__
if type(columns) == str:
self.columns = [columns]
elif type(columns) in (tuple, list):
self.columns = columns
else:
logger.error("Columns must be a str, tuple, or list")
raise UpdaterRoutineException
def __str__(self):
return "Rebuild columns for model %s" % self.model_name
def run(self):
try:
cursor = connection.cursor()
except DatabaseError:
logger.error("Failed to connect to the db")
raise UpdaterRoutineException
db_engine = Bcfg2.settings.DATABASES['default']['ENGINE']
if db_engine == 'django.db.backends.sqlite3':
""" Sqlite is a special case. Altering columns is not supported. """
_rebuild_sqlite_table(self.model)
return
if db_engine == 'django.db.backends.mysql':
modify_cmd = 'MODIFY '
else:
modify_cmd = 'ALTER COLUMN '
col_strings = []
for column in self.columns:
col_strings.append("%s %s %s" % ( \
modify_cmd,
_quote(column),
self.model._meta.get_field(column).db_type()
))
try:
cursor.execute('ALTER TABLE %s %s' %
(_quote(self.model._meta.db_table), ", ".join(col_strings)))
except DatabaseError:
logger.debug("Failed modify table %s" % self.model._meta.db_table)
raise UpdaterRoutineException
class RemoveColumns(RebuildTable):
"""
Routine to remove columns from an existing model
"""
def __init__(self, model, columns):
super(RemoveColumns, self).__init__(model, columns)
def __str__(self):
return "Remove columns from model %s" % self.model_name
def run(self):
try:
cursor = connection.cursor()
except DatabaseError:
logger.error("Failed to connect to the db")
raise UpdaterRoutineException
try:
columns = [d[0] for d in connection.introspection.get_table_description(cursor,
self.model._meta.db_table)]
except DatabaseError:
logger.error("Failed to get table description", exc_info=1)
raise UpdaterRoutineException
for column in self.columns:
if column not in columns:
logger.warning("Cannot drop column %s: does not exist" % column)
continue
logger.debug("Dropping column %s" % column)
db_engine = Bcfg2.settings.DATABASES['default']['ENGINE']
if db_engine == 'django.db.backends.sqlite3':
_rebuild_sqlite_table(self.model)
else:
sql = "alter table %s drop column %s" % \
(_quote(self.model._meta.db_table), _quote(column), )
try:
cursor.execute(sql)
except DatabaseError:
logger.debug("Failed to drop column %s from %s" %
(column, self.model._meta.db_table))
raise UpdaterRoutineException
class DropTable(UpdaterRoutine):
"""
Drop a table
"""
def __init__(self, table_name):
self.table_name = table_name
def __str__(self):
return "Drop table %s" % self.table_name
def run(self):
try:
cursor = connection.cursor()
cursor.execute('DROP TABLE %s' % _quote(self.table_name))
except DatabaseError:
logger.error("Failed to drop table: %s" %
traceback.format_exc().splitlines()[-1])
raise UpdaterRoutineException
class UpdaterCallable(UpdaterRoutine):
"""Helper for routines. Basically delays execution"""
def __init__(self, fn):
self.fn = fn
self.args = []
self.kwargs = {}
def __call__(self, *args, **kwargs):
self.args = args
self.kwargs = kwargs
return self
def __str__(self):
return self.fn.__name__
def run(self):
self.fn(*self.args, **self.kwargs)
def updatercallable(fn):
"""Decorator for UpdaterCallable. Use for any function passed
into the fixes list"""
return UpdaterCallable(fn)
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