Fix compound arrays

[alno]

Calling type_cast for array elements, which fixes serialization of int arrays from strings and compound arrays (for example, arrays of json objects).

Also fixes deserializing compound arrays (calling type_cast for deserialized element)

[kares]

Thanks a lot Alex, but I'm wondering ... is this actually supported by ("native") AR itself ?

[alno]

By my tests deserialization problem isn't present in native AR.

About serialization - there is same issue there. With several open PRs:

• (FIX) Error for array of integers for postgres rails/rails#10340
• Fixing encoding of non-string arrays rails/rails#11159
• Postgres arrays improvements rails/rails#11245

I have no idea why no one of these is merged.

If it's preferred to maintain bug-to-bug compatibility, it may be better not to merge this PR until it will be fixed in native AR.

[kares]

I see ... thanks a lot for the links ... I'm a bit hesitant esp. since you mentioned the [ JSON ] case.

Seems a bit "over-engineering" to me - the meta-data returned by the DB does not provide anything like that and I feel like following what the DB gives us is a good idea (anything more is a bit of a magic) ... while numbers might be fine compound JSON seems like too much - it will also be INconsistent with custom SELECTs where AR column type information does simply not exists (note that nested arrays are not implemented due the same reasons since it's a bit of a "smart" parsing feature not something the DB supports - no one complained about it ... yet :).

But if AR does this than we likely will as well - so we'll wait if you don't mind.
Thank you very much for bringing this up!

[kares]

this issue should now be irrelevant as its handled by the AR-type system introduced in 4.2