Refs #26327 -- Renamed JsonAgg to JSONBAgg.

[atombrella]

Thanks to Christian von Roques for the report.

I added a new flag to indicate availability of JSONB_AGG and fallback to json_agg on PostgreSQL. I tried to test locally for things highlighted in https://www.postgresql.org/docs/9.4/static/datatype-json.html#JSON-KEYS-ELEMENTS but get the same result on both 9.5 and 9.4 using FloatField with the value 1.230e-5.

Are more tests needed? Alternatively, it may be better to disallow use of this function on PostgreSQL 9.4?

[timgraham]

Please update the ticket as described in the "According to the ticket's flags," section to get feedback on the PR.

[charettes]

I find it a bit odd that we ship an aggregate for a datatype we don't use for any fields (JsonField usesjsonb).

As I mentioned on #26327 I'd be more in favor to rename the aggregate JsonbAgg instead.

[atombrella]

I chose the name JSONBAgg and added a few notes in the documentation about availability. I'm also in favor of choosing a name with b in it to specify that this is only for jsonb.

[timgraham]

Simon, is this fine with you?

[timgraham]

Do you think a single sentence would work here: "Returns ... using JSONB_AGG() (requires PostgreSQL 9.5+)."
I'm not sure if the other sentences are adding much.

[atombrella]

Yes. Perhaps "PostgreSQL ships ..." is unnecessary because it's already in the documentation for JSONField.

[charettes]

@timgraham to answer your previous question I also think JSONBAgg is the most appropriate name.

[timgraham]

merged in aa2cb4c, thanks!