postgresql json array query - arrays

Question

I tried to query my json array using the example here: How do I query using fields inside the new PostgreSQL JSON datatype?
They use the example:
SELECT *
FROM json_array_elements(
'[{"name": "Toby", "occupation": "Software Engineer"},
{"name": "Zaphod", "occupation": "Galactic President"} ]'
) AS elem
WHERE elem->>'name' = 'Toby';
But my Json array looks more like this (if using the example):
{
"people": [{
"name": "Toby",
"occupation": "Software Engineer"
},
{
"name": "Zaphod",
"occupation": "Galactic President"
}
]
}
But I get an error: ERROR: cannot call json_array_elements on a non-array
Is my Json "array" not really an array? I have to use this Json string because it's contained in a database, so I would have to tell them to fix it if it's not an array.
Or, is there another way to query it?
I read documentation but nothing worked, kept getting errors.

Answer 1

The json array has a key people so use my_json->'people' in the function:
with my_table(my_json) as (
values(
'{
"people": [
{
"name": "Toby",
"occupation": "Software Engineer"
},
{
"name": "Zaphod",
"occupation": "Galactic President"
}
]
}'::json)
)
select t.*
from my_table t
cross join json_array_elements(my_json->'people') elem
where elem->>'name' = 'Toby';
The function json_array_elements() unnests the json array and generates all its elements as rows:
select elem->>'name' as name, elem->>'occupation' as occupation
from my_table
cross join json_array_elements(my_json->'people') elem
name | occupation
--------+--------------------
Toby | Software Engineer
Zaphod | Galactic President
(2 rows)
If you are interested in Toby's occupation:
select elem->>'occupation' as occupation
from my_table
cross join json_array_elements(my_json->'people') elem
where elem->>'name' = 'Toby'
occupation
-------------------
Software Engineer
(1 row)