Enum recipe on SQLAlchemy 0.8.0 final

[Alex Grönholm]

The following class works on 0.8.0b2 but not 0.8.0 final:
 

class EnumWrapper(SchemaType, TypeDecorator):
    def __init__(self, cls):
        kwargs = {'name': cls.__name__.lower()}
        self.impl = Enum(*(obj.key for obj in cls.values), **kwargs)
        self.wrapped = cls

    def _set_table(self, table, column):
        self.impl._set_table(table, column)

    def process_bind_param(self, value, dialect):
        if value is None:
            return None
        if isinstance(value, self.wrapped):
            return value.key
        elif isinstance(value, str):
            if value not in self.wrapped.symbols:
                raise TypeError('No such enum value in %s: %s' % (self.wrapped.__name__, value))
            return value
        raise TypeError('Expected %s, got %s instead' % (self.wrapped, type(value)))

    def process_result_value(self, value, dialect):
        return getattr(self.wrapped, value) if value is not None else None

The error message ("TypeError: __init__() got an unexpected keyword argument 'schema'") originates from types.py, line 1886.
Is inheriting from SchemaType still necessary? That is what seems to break things on 0.8.0 final.

[Michael Bayer]

Line 1886 of types.py, both in 0.8.0 and in tip, is this:

            t.drop(bind=bind, checkfirst=checkfirst)

so that doesn't seem like the line we're referring to.

Since your example lacks context, I had to modify the call to "Enum" to use a series of string names (don't know what obj.key, cls.values refer to).  From there, I managed to get a stack trace that refers to line 1863 of types.py.

In the documentation for TypeDecorator at http://docs.sqlalchemy.org/en/rel_0_8/core/types.html#sqlalchemy.types.TypeDecorator, the example includes a copy() method.   There is also a copy() method in the original Enum recipe on my blog at http://techspot.zzzeek.org/files/2011/decl_enum.py.

If the constructor of your decorated type is not compatible with the type you're wrapping, you need to provide copy() as well:

    def copy(self):

        return DeclEnumType(self.wrapped)

hope this helps !

[Alex Grönholm]

My bad, it was line 1866: return impltype(name=self.name, ...)

Since your example lacks context, I had to modify the call to "Enum" to use a series of string names (don't know what obj.key, cls.values refer to).  From there, I managed to get a stack trace that refers to line 1863 of types.py.

In the documentation for TypeDecorator at http://docs.sqlalchemy.org/en/rel_0_8/core/types.html#sqlalchemy.types.TypeDecorator, the example includes a copy() method.   There is also a copy() method in the original Enum recipe on my blog at http://techspot.zzzeek.org/files/2011/decl_enum.py.

If the constructor of your decorated type is not compatible with the type you're wrapping, you need to provide copy() as well:

    def copy(self):

        return DeclEnumType(self.wrapped)

Yet, the error goes away once I add something like that. Strange though, everything worked fine even without a copy() method in 0.8.0b2.

Thanks!

hope this helps !

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