Flatten the jsonb nested array in postgresql - sql

Question

I have a data in the table as
id(integer) | label(text) | value(jsonb) |
---------------|-----------------|------------------|
12345 | Education | [[{"label": "Type", "value": "Under Graduate"},{"label": "Location", "value": "New Delhi"}],[{"label": "Type", "value": "Post Graduate"}]]|
And the required output is :
id | label | value |
------|---------------------|----------------|
12345 | Education_Type_1 | Under Graduate |
12345 | Education_Location_1| New Delhi |
12345 | Education_Type_2 | Post Graduate |
Can someone please help me solve this issue that I am facing?

Answer 1

You can use jsonb_array_elements(your_jsonb_column). Tested on Postgres 9.6. You can use json_array_elements(your_json_column) if you are using some other version.
Table:
create table test (id int,label text, value jsonb);
Insert Statement:
insert into test values(12345,'Education','[[{"label": "Type", "value": "Under Graduate"}],[{"label": "Type", "value": "Post Graduate"}]]');
insert into test values(123456,'Education2','[[{"label": "Type2", "value": "Under Graduate2"}],[{"label": "Type2", "value": "Post Graduate2"}]]');
SQL Query:
select id, label,jsonb_array_elements(value)->0->>'value'
from test
Where 0 is used to take first elements from an array.
->> is used to remove quotes from the string.
Output:
id label value
12345 Education Under Graduate
12345 Education Post Graduate
123456 Education2 Under Graduate2
123456 Education2 Post Graduate2
SQL Fiddle

Answer 2

I found the solution. Thanks #Fahad Anjum. I wrote the solution on top of your soultion.
SELECT
'Education_' || (jsonb_array_elements(elem)->>'label')::text || '_' || pos::text AS label, jsonb_array_elements(elem)->>'value'
FROM jsonb_array_elements(
'{"test": [
[{"label":"Type", "value": "Under Graduate"},{"label":"Location", "value": "New Delhi"},{"label":"CGPA", "value": "9.07"}],
[{"label":"Type", "value": "Post Graduate"},{"label":"Location", "value": "Bangalore"}],
[{"label":"Type", "value": "Some education 1"}]]}'::jsonb->'test'
) WITH ordinality arr(elem, pos);

Answer 3

Since we value column is like multi-dimensional array of irregular dimension we will use recursive query to find solution.
Below query result in required output you want
I have populated your sample data in CTE.
with recursive cte(id,label,value,dims) as (
select
12345,
'Education'::text,
'[
[
{"label": "Type", "value": "Under Graduate"},
{"label": "Location", "value":"New Delhi"}
],
[
{"label": "Type", "value": "Post Graduate"}
]
]'::jsonb,
jsonb_array_length('[[{"label": "Type", "value": "Under Graduate"},{"label": "Location", "value": "New Delhi"}],[{"label": "Type", "value": "Post Graduate"}]]'::jsonb)
), res(id,label,val,dims) as (
select cte.id,cte.label,l.v,cte.dims-1
from cte,lateral(
select jsonb_array_elements(cte.value) as v
) l
union all
select
res.id,res.label,l.v,res.dims-1
from res,lateral(
select jsonb_array_elements(res.val) as v
) l
where
res.dims>0
)
select
res.id,
res.val->>'value' as value,
res.label ||
'_'||
(res.val->>'label')::text ||
'_' ||
row_number() over (partition by id,label,(res.val->>'label')::text) as label
from res
where dims=0