Support default values in Postgresql converter

[mjperrone]

Postgres supports setting default values for column values. Recap also supports default values.

Postgres reveals the default value in the information schema, column_default column. This should already be grabbed in the client query, so it could be used in the postgresql converter with column_props["COLUMN_DEFAULT"] to set the right value in the RecapType instantiation.

This came to my attention in #414 (comment)

[criccomini]

@mjperrone I'll take a look at this one. Thanks for raising it.

[criccomini]

@mjperrone I'm not 100% sure what you're seeing broken. The tests/integration/clients/test_postgresql.py test validates that both default=null and default=1 works:

                test_bigint BIGINT,
...
                test_not_null_default INTEGER NOT NULL DEFAULT 1,

These are validated here:

            UnionType(
                default=None,
                name="test_bigint",
                types=[NullType(), IntType(bits=64, signed=True)],
            ),
...
            IntType(bits=32, signed=True, name="test_not_null_default", default="1"),

And these validations are run for both:

test_struct_method_arrays_no_enforce_dimensions
test_struct_method_arrays_enforce_dimensions

The code that sets the default is here:

https://github.com/recap-build/recap/blob/main/recap/converters/dbapi.py#L20

[mjperrone]

That convinces me.
I saw a related error when I was implementing the enums, and then went looking in the postgresql client (not realizing it was a subclass of dbapi) and the postgres converter, and saw no references to default.

That's what I get for not also making a failing test to prove the issue :D

I'll close this, my fault!