Add support for JSONField

[timgraham]

Fixes #23

[timgraham]

@sfc-gh-mkeller I'm wondering if have you a sense of whether or not this issue and the below issues mentioning "needs to operate as" (where PARSE_JSON() is needed on the right-hand side of the query) will be solved by snowflakedb/snowflake-connector-python#244? I don't know if it's possible to work around here until then.

Also, feel free to comment on any of the other failures here if you have any suggestions.

[sfc-gh-mkeller]

I think it'd make sense if you did "MODEL_FIELDS_NULLABLEJSONMODEL"."VALUE"[123] if the key is an integer and do the "MODEL_FIELDS_NULLABLEJSONMODEL"."VALUE":"123" if the key is a string.
The JSON standard only allows string keys.

[timgraham]

I think your comment refers to test_has_key_number' which I solved last night in the latest commit. I was actually asking about cases like this:

WHERE TO_JSON("MODEL_FIELDS_NULLABLEJSONMODEL"."VALUE":k) = '{"l": "m"}'

where the right-hand side parameter is treated as a string literal rather than as JSON.

A working version of this query is:

WHERE TO_JSON("MODEL_FIELDS_NULLABLEJSONMODEL"."VALUE":k) = PARSE_JSON('{"l": "m"}')

but I'm not sure this is feasible to implement here. I thought maybe when/if the Python connector gains awareness of VARIANT type, the first query might work as expected.

[timgraham]

I've documented this as a known limitation: #58.

[timgraham]

Some other databases implement JSON_CONTAINS() (@> and <@ on PostgreSQL). Is it unsupported by Snowflake or did I miss an equivalent?

[sfc-gh-mkeller]

You can treat JSON columns as regular VARIANT columns, like:

select *
from (
  select parse_json(column1) as user
  from (
    select * from values
    ('{"name": "Luke", "age": 25}'),
    ('{"name": "Mark", "age": 35}')
  )
) where user ilike '%luke%'
;

We don't have any special JSON variants of this as far as I know

[timgraham]

I'm not sure we can (easily?) use regular expressions since the example code you gave will also match JSON keys. I'll call this unsupported, at least for now.