psycopg2 query parameter types

Question

I have a python script that calls a postgresql proc using psycopg2. The proc has the following signature.

CREATE FUNCTION utility_function(p_id_file bigint, p_size bigint, p_id_volume smallint, p_id_type_file bigint, p_id_user bigint) RETURNS void

When I call it with the following code, I get this error...

Traceback (most recent call last):
  File "/tmp/regenerate/regenerate.py", line 173, in <module>
    execute_process(db, out_csv, out_file, start_date, end_date, limit, offset)
  File "/tmp/regenerate/regenerate.py", line 57, in execute_process
    db.execute(sql, (id_file, size, id_volume, id_type_file, id_user))
psycopg2.ProgrammingError: function utility_function(integer, integer, integer, integer, integer) does not exist
LINE 1: select * from utility_function(13456, 132456798, 0...
                      ^
HINT:  No function matches the given name and argument types. You might need to add explicit type casts.

I can't figure out how to cast the parameters to the correct postgresql type.

The python code looks like this.

sql = 'select * from utility_function(%s, %s, %s, %s, %s)'
logging.debug(db.mogrify(sql, (id_file, size, id_volume, id_type_file, id_user)))
db.execute(sql, (id_file, size, id_volume, id_type_file, id_user))

db.mogrify returns this:

select * from utility_regenerate_tsstream(13456, 132456798, 0, 42, 1324)

Thanks in advance for your help :) Sam

Answer 1

您可以将查询中的类型指定为强制转换：

sql = 'select * from utility_function(%s::bigint, %s::bigint, %s::smallint, %s::bigint, %s::bigint)'

Answer 2

I've managed to overcome the problem by changing the parameter type of the proc from smallint to int. It seems that psycopg2 doesn't handle the type inference for smallint...

p_id_volume smallint -> p_id_volume int

No other changes were needed.