BUG: Fix handling of Array types in Postgres UDF

[scottcode]

Other scalar types can be represented either by the class or an instance, but Array types work differently. Array types must be an instance, because the Array class must be instantiated specifying the datatype of the elements of the array. This was causing an error in the translation.

ibis/sql/postgres/tests/test_udf.py:176 (test_array_type)
con_for_udf = <ibis.sql.postgres.client.PostgreSQLClient object at 0x11eb3ada0>
test_schema = 'udf_test_18'
table = PostgreSQLTable[table]
  name: udf_test_users
  schema:
    user_id : int32
    user_name : string
    name_length : int32

    def test_array_type(con_for_udf, test_schema, table):
        """Test that usage of Array types work
        Other scalar types can be represented either by the class or an instance,
        but Array types work differently. Array types must be an instance,
        because the Array class must be instantiated specifying the datatype
        of the elements of the array.
        """
        pysplit_udf = udf(
            con_for_udf,
            pysplit,
            (dt.string, dt.string),
            dt.Array(dt.string),
            schema=test_schema,
>           replace=True,
        )

test_udf.py:190: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
../udf/api.py:179: in udf
    return_type = ibis_to_postgres_str(out_type)
../udf/api.py:43: in ibis_to_postgres_str
    return sa_type_to_postgres_str(ibis_to_pg_sa_type(ibis_type))
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

sa_type = ARRAY(Text())

    def sa_type_to_postgres_str(sa_type):
        """Map a Postgres-compatible sqlalchemy type to a Postgres-appropriate
        string"""
>       return sa_type().compile(dialect=sa_postgres_dialect())
E       TypeError: 'ARRAY' object is not callable

[xmnlab]

hey @scottcode sorry for the delay .. I will review that today after lunch

[xmnlab]

thanks @scottcode for fixing this issue.

[jreback]

note that we should be doing release notes on the patches themselves

[xmnlab]

currently ibis is using https://github.com/ibis-project/ibis/blob/master/dev/genrelease.py to create automatically the release notes.

I don't know much about this script but maybe @cpcloud could give us an idea and we can add that to the documentation.

[xmnlab]

sympy has a nice bot for release notes https://github.com/sympy/sympy-bot .. not sure if it could be integrated easily to ibis current workflow

[jreback]

-1 on using bots or scripts for this

the notes should be in the patch PR it’s way more readable and ultimately causes much less work

[xmnlab]

I don't mind to use one or the other approach. I think the most important thing is to document the approach that should be used and make it clear for anyone during the PR phase .. maybe using a github PR template.

[xmnlab]

but as I commented .. the current approach is the script.
maybe we could discuss that on gitter or an issue .. or we can reschedule our meeting to be early and discuss that.

[scottcode]

-1 on using bots or scripts for this

the notes should be in the patch PR it’s way more readable and ultimately causes much less work

@jreback Assuming we go this route, what should I do? Edit the message of the pull request? If so, could you point me to a good example to emulate? Thanks for any pointers. Writing better pull request messages or other documentation sounds like a good idea regardless.

[jreback]

like this: https://github.com/ibis-project/ibis/pull/2009/files

this is by far the easiest way to go as it packages the PR and the release note in a single commit on merge. its also community reviewed.

[scottcode]

@jreback Thanks for pointing me to a good example of adding to the release notes. I'll follow that with my future pull requests.

[xmnlab]

if we will following this way .. maybe we need to take care about the previous PR merged .. maybe run for the last time the release script to update the release notes ... and update the documentation https://docs.ibis-project.org/contributing.html#releasing ... also maybe a PR template to guide the contributor to create the release notes.

[scottcode]

@xmnlab For this current issue, should I create another PR adding to the release notes? Just let me know and I can do that.

[xmnlab]

@scottcode if you want to do it, go ahead :)
I will open an issue to keep this discussion opened if there is any objection.
maybe discuss guidelines etc.