id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
30788	Fix concatenation of tuple to list (or vice versa)	Dmitry Mugtasimov	nobody	"Sometimes you may get 
{{{
TypeError: can only concatenate tuple (not ""list"") to tuple
}}}

As you see it happens because lhs_params is tuple and rhs_params is list.
{{{
    def as_sql(self, qn, connection):
        lhs, lhs_params = self.process_lhs(qn, connection)
        rhs, rhs_params = self.process_rhs(qn, connection)
>       params = lhs_params + rhs_params
E       TypeError: can only concatenate tuple (not ""list"") to tuple

connection = <django.db.backends.postgresql.base.DatabaseWrapper object at 0x7f4845880b38>
lhs        = '(SELECT ARRAY_AGG(U0.""experience_id"" ) AS ""experience_levels"" FROM ""jobs_jobtitleexperiencetrough"" U0 WHERE U0.""title_id"" = ANY((""jobs_job"".""titles"")))'
lhs_params = ()
qn         = <django.db.models.sql.compiler.SQLCompiler object at 0x7f483d658860>
rhs        = '%s'
rhs_params = [(21,)]
self       = <django.contrib.postgres.fields.array.ArrayContains object at 0x7f483d67a0f0>

}}}

This is because of implementation of PostgresSimpleLookup:

{{{
class PostgresSimpleLookup(Lookup):
    def as_sql(self, qn, connection):
        lhs, lhs_params = self.process_lhs(qn, connection)
        rhs, rhs_params = self.process_rhs(qn, connection)
        params = lhs_params + rhs_params
        return '%s %s %s' % (lhs, self.operator, rhs), params
}}}

I use this workaround:

{{{
class FixedArrayContains(DataContains):
    def super_as_sql(self, qn, connection):
        lhs, lhs_params = self.process_lhs(qn, connection)
        rhs, rhs_params = self.process_rhs(qn, connection)
        params = list(lhs_params) + list(rhs_params)
        return '%s %s %s' % (lhs, self.operator, rhs), params

    def as_sql(self, qn, connection):
        sql, params = self.super_as_sql(qn, connection)
        sql = '%s::%s' % (sql, self.lhs.output_field.db_type(connection))
        return sql, params

}}}

Please, provide a solution
"	Bug	closed	Database layer (models, ORM)	dev	Normal	duplicate	postgresql	Massimo Costa	Unreviewed	0	0	0	0	0	0