json extract multiple level value in sql - sql

Question

This is a follow-up question of Extract all values from json in sql table
What if the json value has multiple levels?
For example,
{
"store-1": {
"Apple": {
"category": "fruit",
"price": 100
},
"Orange": {
"category": "fruit",
"price": 80
}
},
"store-2": {
"Orange": {
"category": "fruit",
"price": 90
},
"Potato": {
"category": "vegetable",
"price": 40
}
}
}
In this case, I want to extract the price for all the items. But I get error when I run the below query.
with my_table(items) as (
values (
'{"store-1":{"Apple":{"category":"fruit","price":100},"Orange":{"category":"fruit","price":80}},
"store-2":{"Orange":{"category":"fruit","price":90},"Potato":{"category":"vegetable","price":40}}}'::json
)
)
select key, (value->value->>'price')::numeric as price
from my_table,
json_each(json_each(items))
I get the below error.
ERROR: function json_each(record) does not exist
LINE 10: json_each(json_each(items))
If I remove one json_each(), it throws
ERROR: operator does not exist: json -> json
LINE 8: select key, (value->value->>'price')::numeric as price

Answer 1

You can use lateral join, something like:
with my_table(items) as (
values (
'{"store-1":{"Apple":{"category":"fruit","price":100},"Orange":{"category":"fruit","price":80}},
"store-2":{"Orange":{"category":"fruit","price":90},"Potato":{"category":"vegetable","price":40}}}'::json
)
)
select outer_key, key, value->>'price' from (
select key as outer_key, value as val from my_table
join lateral json_each(items)
on true
)t
join lateral json_each(val)
on true