Get aggregate sum of json array in Postgres NOSQL json data - json

Question

How to get aggregate SUM(amount) from "refunds" array in postgres json select
Following is my data schema and structure:
Table Name: transactions
Column name: data
{
"id": "tran_6ac25129951962e99f28fa488993",
"amount": 1200,
"origin_amount": 3900,
"status": "partial_refunded",
"description": "Subscription#sub_a67d59efb2bcbf73485a ",
"livemode": false,
"refunds": [
{
"id": "refund_ee4192ffb6d2caa490a1",
"amount": 1200,
"status": "refunded",
"created_at": 1426412340,
"updated_at": 1426412340,
},
{
"id": "refund_0e4a34e4ee7281d369df",
"amount": 1500,
"status": "refunded",
"created_at": 1426412353,
"updated_at": 1426412353,
}
]
}
Out put should be: 1200+1500 = 2700
Output
|---------
|total
|---------
|2700
Please provide global solution and not with static data

Answer 1

This should work on 9.3+
WITH x AS( SELECT
'{
"id": "tran_6ac25129951962e99f28fa488993",
"amount": 1200,
"origin_amount": 3900,
"status": "partial_refunded",
"description": "Subscription#sub_a67d59efb2bcbf73485a ",
"livemode": false,
"refunds": [
{
"id": "refund_ee4192ffb6d2caa490a1",
"amount": 1200,
"status": "refunded",
"created_at": 1426412340,
"updated_at": 1426412340
},
{
"id": "refund_0e4a34e4ee7281d369df",
"amount": 1500,
"status": "refunded",
"created_at": 1426412353,
"updated_at": 1426412353
}
]
}'::json as y),
refunds AS(
SELECT json_array_elements(y->'refunds') as j FROM x)
SELECT sum((j->>'amount')::int) FROM refunds;

Answer 2

WITH AllRefunds AS ( SELECT jsonb_array_elements(data->'refunds') AS refund FROM transactions)
SELECT SUM( CAST ( refund ->> 'amount' AS INTEGER )) FROM AllRefunds;
If you need to know how the query is built:
1.
WITH AllRefunds AS ( SELECT jsonb_array_elements(data->'refunds') FROM transactions)
SELECT * FROM AllRefunds;
This selects all elements as JSON objects (done via ->) from the array refunds that were found in transactions table and stores it in a new table AllRefunds. This new table only consists of one unnamed column.
2.
WITH AllRefunds AS ( SELECT jsonb_array_elements(data->'refunds') AS refund FROM transactions)
SELECT * FROM AllRefunds;
Here the added (second) AS renames the currently unnamed column inside AllRefunds to refund
3.
WITH AllRefunds AS ( SELECT jsonb_array_elements(data->'refunds') AS refund FROM transactions)
SELECT SUM( CAST ( refund ->> 'amount' AS INTEGER )) FROM AllRefunds;
Our array entries are JSON objects. So we return the field amount as a simple string with ->> that we then cast to Integers and SUM all entries up.