[Sqlalchemy-tickets] Issue #3467: Array of enums does not allow assigning (zzzeek/sqlalchemy)

[Wichert A. <iss...@bi...>]

New issue 3467: Array of enums does not allow assigning
https://bitbucket.org/zzzeek/sqlalchemy/issue/3467/array-of-enums-does-not-allow-assigning

Wichert Akkerman:

There is an overlap with #2940 here.

I have an array of enums:

```python
topping = sa.Enum('spinach', 'feta', 'pinenuts', name='topping')

Base = declarative_base()

class Pizza(Base):
    __tablename__ = 'pizza'
    id = sa.Column(sa.Integer(), primary_key=True)
    toppings = sa.Column(ARRAY(topping))
```

With that minimal model I try to creating a new pizza instance with some toppings:

```python
pizza = Pizza(toppings=['feta', 'spinach'])
session.add(pizza)
session.flush()
```

which results in this error:

```
Traceback (most recent call last):
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/engine/base.py", line 1139, in _execute_context
    context)
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/engine/default.py", line 442, in do_execute
    cursor.execute(statement, parameters)
psycopg2.ProgrammingError: column "toppings" is of type topping[] but expression is of type text[]
LINE 1: INSERT INTO pizza (toppings) VALUES (ARRAY['feta', 'spinach'...
                                             ^
HINT:  You will need to rewrite or cast the expression.


The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "x.py", line 25, in <module>
    session.flush()
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/orm/session.py", line 2004, in flush
    self._flush(objects)
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/orm/session.py", line 2122, in _flush
    transaction.rollback(_capture_exception=True)
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/util/langhelpers.py", line 60, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/util/compat.py", line 182, in reraise
    raise value
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/orm/session.py", line 2086, in _flush
    flush_context.execute()
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/orm/unitofwork.py", line 373, in execute
    rec.execute(self)
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/orm/unitofwork.py", line 532, in execute
    uow
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/orm/persistence.py", line 174, in save_obj
    mapper, table, insert)
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/orm/persistence.py", line 761, in _emit_insert_statements
    execute(statement, params)
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/engine/base.py", line 914, in execute
    return meth(self, multiparams, params)
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/sql/elements.py", line 323, in _execute_on_connection
    return connection._execute_clauseelement(self, multiparams, params)
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/engine/base.py", line 1010, in _execute_clauseelement
    compiled_sql, distilled_params
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/engine/base.py", line 1146, in _execute_context
    context)
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/engine/base.py", line 1339, in _handle_dbapi_exception
    exc_info
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/util/compat.py", line 188, in raise_from_cause
    reraise(type(exception), exception, tb=exc_tb, cause=exc_value)
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/util/compat.py", line 181, in reraise
    raise value.with_traceback(tb)
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/engine/base.py", line 1139, in _execute_context
    context)
  File "/Users/wichert/Jzoo/backend/lib/python3.4/site-packages/sqlalchemy/engine/default.py", line 442, in do_execute
    cursor.execute(statement, parameters)
sqlalchemy.exc.ProgrammingError: (psycopg2.ProgrammingError) column "toppings" is of type topping[] but expression is of type text[]
LINE 1: INSERT INTO pizza (toppings) VALUES (ARRAY['feta', 'spinach'...
                                             ^
HINT:  You will need to rewrite or cast the expression.
 [SQL: 'INSERT INTO pizza (toppings) VALUES (%(toppings)s) RETURNING pizza.id'] [parameters: {'toppings': ['feta', 'spinach']}]
```

This is using SQLAlchemy 1.0.4 and psycopg2 2.5.4.