django + south + python: strange behavior when using a text string received as a parameter in a func
- by carlosescri
Hello, this is my first question.
I'm trying to execute a SQL query in django (south migration):
from django.db import connection
# ...
class Migration(SchemaMigration):
# ...
def transform_id_to_pk(self, table):
try:
db.delete_primary_key(table)
except:
pass
finally:
cursor = connection.cursor()
# This does not work
cursor.execute('SELECT MAX("id") FROM "%s"', [table])
# I don't know if this works.
try:
minvalue = cursor.fetchone()[0]
except:
minvalue = 1
seq_name = table + '_id_seq'
db.execute('CREATE SEQUENCE "%s" START WITH %s OWNED BY "%s"."id"', [seq_name, minvalue, table])
db.execute('ALTER TABLE "%s" ALTER COLUMN id SET DEFAULT nextval("%s")', [table, seq_name + '::regclass'])
db.create_primary_key(table, ['id'])
# ...
I use this function like this:
self.transform_id_to_pk('my_table_name')
So it should:
Find the biggest existent ID or 0 (it crashes)
Create a sequence name
Create the sequence
Update the ID field to use sequence
Update the ID as PK
But it crashes and the error says:
File "../apps/accounting/migrations/0003_setup_tables.py", line 45, in forwards
self.delegation_table_setup(orm)
File "../apps/accounting/migrations/0003_setup_tables.py", line 478, in delegation_table_setup
self.transform_id_to_pk('accounting_delegation')
File "../apps/accounting/migrations/0003_setup_tables.py", line 20, in transform_id_to_pk
cursor.execute(u'SELECT MAX("id") FROM "%s"', [table.encode('utf-8')])
File "/Library/Python/2.6/site-packages/django/db/backends/util.py", line 19, in execute
return self.cursor.execute(sql, params)
psycopg2.ProgrammingError: relation "E'accounting_delegation'" does not exist
LINE 1: SELECT MAX("id") FROM "E'accounting_delegation'"
^
I have shortened the file paths for convenience.
What does that "E'accounting_delegation'" mean? How could I get rid of it?
Thank you!
Carlos.
