On 08/25/2014 01:53 PM, David E. Wheeler wrote:
On Aug 25, 2014, at 10:52 AM, Greg Sabino Mullane <[email protected]> wrote:
The biggest problem is that any composite types are going to be user-defined
types, and thus DBD::Pg cannot know about them in advance (as it does for
arrays). This problem has reared its head already. We can query the system
catalogs to gather information about data types, but the key point is when?
On connection? When we encounter an unknown type? (tricky, as we are already
inside of an active transaction). Perhaps allow the user to call some method
that tells us to grab the information? I'm thinking some combination of
the former and latter will work: allows a connection attribute that says
"grab information about all user types right after you connect" as well as a
method that does the same thing (or allows some wildcards, etc.). Once that
is in place, it should be relatively easy to roll multiple columns into a
hashref .. I think. Haven't actually dug into that part of the code yet :)
OTOH, would be awesome to have an attribute to serialize and deserialize JSON
and JSONB values. :-)
Well, of course, json and jsonb are already serializations. Even jsonb
in binary mode is sent to the client as a json string (with a version
number in case we ever decide to send/receive a different binary format).
And turning a composite into json is pretty simple - in 9.4 it's just
to_json(recordval). populate_json(null::recordtype, jsonval) pretty much
does the reverse. On the perl side there are well known modules for
moving between hashes and json objects. Maybe with some sort of Tie
mechanism you could make that almost transparent?
cheers
andrew
