Thanks for the advice. I pursued the TypeDecorator path, and I'm
relatively happy with something along these lines:
class HStoreType(UserDefinedType):
"""PostgreSQL-specific ``hstore`` storage type."""
python_type = dict
def get_col_spec(self):
return 'hstore'
class DictionaryType(TypeDecorator):
"""Backend-agnotic dictionary storage type."""
impl = TypeEngine
def load_dialect_impl(self, dialect):
if dialect.name == 'postgresql':
return dialect.type_descriptor(HStoreType())
return dialect.type_descriptor(PickleType())
On Mon, Jul 9, 2012 at 6:36 AM, Michael Bayer <mike...@zzzcomputing.com> wrote:
>
> with_variant() is a straightforward way to go, you just give any existing
> type the per-dialect variants you want:
>
> mytype = MyHstoreType.with_variant(MyPGHstore, "postgresql")
>
> if you were using TypeDecorator, you could also add this in using the
> load_dialect_impl() method. That's the end effect of with_variant() in any
> case (it creates a new TypeDecorator).
>
>
>
> On Jul 9, 2012, at 12:38 AM, Jon Parise wrote:
>
>> I have a simple HStore(UserDefinedType) implementation that works well
>> with PostgreSQL. I'd also like to provide a more generic HStore
>> implementation that can be used with SQLite for in-memory unit testing
>> databases. That fallback implementation could be implemented in terms
>> of pickled or JSON-encoded dictionaries.
>>
>> For my purposes, I'm only interested in bulk dictionary storage. I
>> don't need a full hstore implementation complete with query language
>> support, etc.
>>
>> What is the recommended way to expose these two specialized type
>> implementations? It looks like the .with_variant() method might be
>> helpful here, but the documentation on type variants is slim enough
>> that I thought it best to ask here first.
>>
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