Select JSON value from a EAV structure result set - postgresql

Question

Given a result set which is in the EAV structure such as :
id | attributeName | stringValue | intValue | BooleanValue
---------------------------------------------------------------
1 stringFoo v1
1 stringFooList v2
1 stringFooList v3
1 intFoo 10
1 intFooList 10
1 intFooList 20
1 booleanFoo true
1 booleanFooList true
1 booleanFooList true
How can I select all the attributes and value pair as a single value in a JSON/JSONB format , which are something likes:
{
"stringFoo" : "v1" ,
"stringFooList" : ["v2","v3"] ,
"intFoo" : 10 ,
"intFooList" : [10,20],
"booleanFoo" : true,
"booleanFooList" : [true,true]
}
If there are multiple attribute value for an attribute such as stringFooList , it will format it as JSON array.
I am using PostgreSQL 9.6

Answer 1

You can do something like this:
select id, jsonb_object_agg(att, value)
from (
select id,
attributename as att,
case
when count(*) > 1 then
jsonb_agg(coalesce(stringvalue,intvalue::text,booleanvalue::text))
else
to_jsonb(min(coalesce(stringvalue,intvalue::text,booleanvalue::text)))
end as value
from eav
group by id, attributename
) t
group by id;
The inner select aggregates multiple values into an JSON array, single values into JSON scalar values. And the outer query then builds a single JSON value of all rows.
Online example: https://rextester.com/TLCRN79815

Answer 2

#a_horse_with_no_name 's answer gives me a good start. I extend his/her answer and come up the following query such that the elements in the JSON array have the same data type of what defined in PostgreSQL.
select id, jsonb_object_agg(att,
case
when strval is not null then strval
when intvalue is not null then intvalue
else boolVal
end
)
from (
select id,
attributename as att,
case when count(*) > 1 then
jsonb_agg(stringvalue) filter (where stringvalue is not null)
else
to_jsonb(min(stringvalue) filter (where stringvalue is not null))
end as strVal,
case when count(*) > 1 then
jsonb_agg(intvalue) filter (where intvalue is not null)
else
to_jsonb(min(intvalue) filter (where intvalue is not null))
end as intvalue,
case when count(*) > 1 then
jsonb_agg(booleanvalue) filter (where booleanvalue is not null)
else
to_jsonb(bool_and(booleanvalue) filter (where booleanvalue is not null))
end as boolVal
from eav
group by id, attributename
) t
group by id;