Implementing custom column types

Hello,

I just recently stumbled upon Piccolo and I’m very impressed so far with how much thought and effort has been put into it. Modern Python desperately needs an ORM that can keep up with the next generation of web development libraries. Piccolo looks to be well on it’s way to fill that need.

I have a project in mind that I could use Piccolo with, but it does have a use case that requires the use of a PostGIS geography type column. I’ve been looking through https://github.com/piccolo-orm/piccolo/blob/master/piccolo/columns/base.py and it doesn’t look too daunting to subclass Column and go from there. If I can get something useable, even with using raw for selects, it would be pretty great.

Since there doesn’t seem to be any documentation on implementing custom columns, I’d figure I’d post an issue, even if there isn’t really a problem yet just in case anyone had any advice or thoughts.

[dantownsend]

@Fingel I think those issues are all solvable, but will require some changes to Piccolo.

1. Custom column types could be registered in piccolo_conf.py, which solves the migration issue.
2. In terms of adding custom methods like ST_Dwithin, the best analogy so far is the JSONB column type, which has an arrow method. Something similar to this could be implemented.
3. With raw SQL in where clauses - this also shouldn’t be too tricky, and I can add this.

I should be able to get 1 and 3 done in the next day or so. Otherwise you might want to fork it for now.

[dantownsend]

Going to close this for now - custom column types should now be possible.