JSON::Any is more used for parsing JSON in a generic way. There won't be much use of Int32/Float32 in those cases: parsing {"a":1} is a Int32 or Int64? The use will need to deal with the union all the time an Int is expected.

crystal-mysql should use Int64/Float64 when building a JSON in a straight way.

On a given schema, a JSON.mapping could be supported though and there a lot of flexibility can be achieved.

Note: I am eager to see that JSON addition in mysql :-), so big 👍 there.

I don't know if I implement it correctly as I am just newbie with Crystal but it works for me. crystal-lang/crystal-mysql#24

I actually have my doubts about automatically parsing a JSON field from a database. crystal-pg does that too, but I think we should just return a String. Since you are probably in control of the database you know what you put in that column typed as JSON, and the best thing to do is to use JSON.mapping with that. If you get the result already parsed there's no way to use JSON.mapping. So I would drop that from all drivers and return String instead.

Thats also a good point. I started by extending only string with native json type it was working but I went bit further and added json parsing and generation as it is json type...

Since the JSON can be a type interpreted by the database (as parameters also, not just query results). I wouldn't mind for the drivers to support them. But I would also expect that if the schema is fixed a JSON.mapping or other strict parsing technique will be used.

Probably there is no performance difference between a native json representation of the driver and just the json-to-io done by crystal, so is more an api discussion than a discussion about what happens under the hood.

But sometimes json is used to store not fixed schema data. JSON.mapping might be a bit annoying here. So I am not totally sure JSON should be discarded as a first class citizen in the db family.

I'll close this. We can continue the discussion of json & db at crystal-lang/crystal-mysql#24 or maybe even at crystal-db since most of the drivers supports json nowadays.

Yeah, ok 👍