Null instead of null values in jsonb_build_object - sql

Question

I am trying to build query that gets data from 3 different tables using sqlalchemy
I tried
select(
models.Animals.id,
models.Animals.description,
models.AnimalTypes.name.label('type'),
func.coalesce(
func.array_agg(
func.jsonb_build_object(
'id',
models.Animals.id
)
), None
).label('animals')
)
.join(models.FamilyTypes, models.Family.id == models.Family.family_type_id)
.outerjoin(models.Animals, models.Animals.campaign_id == models.Animals.id)
.group_by(models.Family.id, models.FamilyType.name)
i expect to get animals:null instead of animals:{"id": null}

Answer 1

Not an answer, just a longer comment. Using psql on a local test table. Using jsonb_agg from Aggregate functions:
select jsonb_agg(animals.*) from animals;
test(5432)=# select * from animals;
pk_animals | cond | animal
------------+-------+--------
2 | good | eagle
3 | good | mole
16 | fair | heron
33 | fair | mole
200 | good | crow
35 | good | emu
101 | good | gopher
45 | poor | dog
50 | great | deer
\pset format wrapped
select jsonb_agg(animals.*) from animals;
jsonb_agg
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
[{"cond": "good", "animal": "eagle", "pk_animals": 2}, {"cond": "good", "animal": "mole", "pk_animals": 3}, {"cond": "fair", "animal": "heron", "pk_animals": 16}, {"cond": "fair.
.", "animal": "mole", "pk_animals": 33}, {"cond": "good", "animal": "crow", "pk_animals": 200}, {"cond": "good", "animal": "emu", "pk_animals": 35}, {"cond": "good", "animal": "g.
.opher", "pk_animals": 101}, {"cond": "poor", "animal": "dog", "pk_animals": 45}, {"cond": "great", "animal": "deer", "pk_animals": 50}]

Answer 2

Solved this using case
case(
(func.count(models.Animals.id) == 0, None),
else_=(
func.array_agg(
func.jsonb_build_object(
'id',
models.Animals.id,
...
)
)
),
).label('animals')