How can I bind a list to a parameter in a custom query in SQLAlchemy?

Question

I am using this SQL for performance reasons:

 sql_tmpl = """delete from Data where id_data in (:iddata) """  params = {                     'iddata':[1, 2,3 4],                     }   # 'session' is a session object from SQLAlchemy  self.session.execute(text(sql_tmpl), params) 

However, I got an exception:

NotSupportedError: (NotSupportedError) ('Python type list not supported.  param=1', 'HY097') 

Is there a workaround that can allow me to bind a list to the parameter of the 'in' clause?

Answer 1

A new approach to this problem that works for any database (not just relying on psycopg2's type adaptation) uses expanding bind parameters:

sql_tmpl = """delete from Data where id_data in :iddata""" params = { 'iddata': [1, 2, 3, 4], } # session is a session object from sqlalchemy t = text(sql_tmpl) t = t.bindparams(bindparam('iddata', expanding=True)) self.session.execute(t, params) 

Answer 2

psycopg2 now supports type adaptation, which allows, among other things, the ability to pass a list into a single parameterized value in the query. This also works in SQLAlchemy, at the very least for raw-SQL-esque queries to a PostgreSQL database (I don't have access to other database types, so I don't know if sqlalchemy will respect this convention for other databases, but my inclination^{citation needed} is that it will work).

some_ids = [1, 2, 3, 4] query = "SELECT * FROM my_table t WHERE t.id = ANY(:ids);" conn.execute(sqlalchemy.text(query), ids=some_ids) ## runs just fine 

I found that without the wrapper call to sqlalchemy.text, it gave a ProgrammingError: syntax error at or near ":".