Question

I want to execute postgres query in python.The table name has to be passed as a parameter.Since the table will be created at run time. I have used dict query param style.But i am getting an error.

 import psycopg2

 CONNECTION_STRING = "dbname='autogist' user='postgres' password=''"
 query = "INSERT INTO %(table)s " +\
            "(vin_id, vin_details_id, price, mileage, dealer_id, created_on, modified_on) " +\
            "VALUES (%(vin_id)s, %(vlookup_id)s, %(price)s, %(mileage)s, %(dealer_id)s,now(),now()) " +\
            "RETURNING id"


params = {"table" : "dealer_vehicle_details_2010_01_02",\
                      "vin_id":"3",\
                      "vlookup_id":"403",\
                      "price":"403",\
                      "mileage":"403",\
                      "dealer_id":"276092"
                  }


 conn=psycopg2.connect(CONNECTION_STRING)
 cursor = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
 cursor.execute(query,params)

TRACEBACK:

 ERROR: An unexpected error occurred while tokenizing input
The following traceback may be corrupted or invalid
The error message is: ('EOF in multi-line statement', (262, 0))

---------------------------------------------------------------------------
 ProgrammingError                          Traceback (most recent call last)

 /home/gridlex/workspace/<ipython console> in <module>()

 /usr/local/lib/python2.6/dist-packages/psycopg2/extras.pyc in execute(self, query, vars)
121         self.index = {}
122         self._query_executed = 1
--> 123         return _cursor.execute(self, query, vars)
124 
125     def callproc(self, procname, vars=None):

ProgrammingError: syntax error at or near "E'dealer_vehicle_details_2010_01_02'"
LINE 1: INSERT INTO E'dealer_vehicle_details_2010_01_02' (vin_id, vi...

Answer 1

The statement you send must be syntactically valid when PREPAREd, which a statement with placeholders for table names is not. You can’t use placeholders for table names in prepared statements.

Your options are:

• Substitute the table name in with regular string substitution, "double quoted". Be very careful with your quoting routine; make sure it doubles any quotes within the table name its self, so the table name double"quote becomes "double""quote". Eg. 'SELECT * FROM "%s"' % quote_ident(tablename). You’d have to roll your own quote_ident as AFAIK psycopg2 doesn’t expose a function like that.

• Send the table name as a query parameter to a PL/PgSQL function that uses EXECUTE ... USING to create a dynamic SQL statement using the table name. PL/PgSQL can use the quote_ident function to provide safer quoting than a home-rolled implementation.