Postgres jsonb, nested array querying to hide specific fields - postgresql

Question

I have a jsonb data of following format, with nested arrays
{
"outerArray": [
{
"price": {
"amount": 108.95,
"currencyCode": "GBP"
},
"innerArray": [
{
"details": {
"field1": "val1",
"field2": "val2",
"field3": "val3"
},
"otherDetail": {
"date": "2016-07-23",
"time": "19:43:00"
},
"innerMostArray": [
{
"A1": "A1"
},
{
"B1": "B1"
}
]
}
],
"someField": "values"
},
{
"price": {
"amount": 108.95,
"currencyCode": "GBP"
},
"innerArray": [
{
"details": {
"field1": "val1",
"field2": "val2",
"field3": "val3"
},
"otherDetail": {
"date": "2016-07-23",
"time": "19:43:00"
},
"innerMostArray": [
{
"A1": "A1"
},
{
"B1": "B1"
}
]
}
],
"someField": "values"
}
]
}
I want to write a retrieve query on this, to maintain same json structure but hide fields "price", "details" , "otherDetail"and "someField"
The retrieved result should look like this
{
"outerArray": [
{
"innerArray": [
{
"innerMostArray": [
{
"A1": "A1"
},
{
"B1": "B1"
}
]
}
]
},
{
"innerArray": [
{
"innerMostArray": [
{
"A1": "A1"
},
{
"B1": "B1"
}
]
}
]
}
]
}
Can this be done?

Answer 1

Please always specify a version of PostgreSQL you are using. An example below should work fine for versions v9.5+.
I would approach this by building a JSONB object you need with jsonb_build_object() and jsonb_build_array() functions:
Sample query:
WITH test(data) AS ( VALUES
('{
"outerArray": [
{
"price": {
"amount": 108.95,
"currencyCode": "GBP"
},
"innerArray": [
{
"details": {
"field1": "val1",
"field2": "val2",
"field3": "val3"
},
"otherDetail": {
"date": "2016-07-23",
"time": "19:43:00"
},
"innerMostArray": [
{
"A1": "A1"
},
{
"B1": "B1"
}
]
}
],
"someField": "values"
},
{
"price": {
"amount": 108.95,
"currencyCode": "GBP"
},
"innerArray": [
{
"details": {
"field1": "val1",
"field2": "val2",
"field3": "val3"
},
"otherDetail": {
"date": "2016-07-23",
"time": "19:43:00"
},
"innerMostArray": [
{
"A1": "A1"
},
{
"B1": "B1"
}
]
}
],
"someField": "values"
}
]}'::JSONB)
)
SELECT
jsonb_build_object(
'outerArray',
array_agg(
jsonb_build_object(
'innerArray',
json_build_array(
json_build_object(
'innerMostArray',
innerArray->'innerMostArray')
)
)
)
) as result
FROM test t,
jsonb_array_elements(t.data->'outerArray') as outerElement,
jsonb_array_elements(outerElement->'innerArray') as innerArray;
Result:
result
----------------------------------------------------------------------------------------------------------------------------------------------------------
{"outerArray": [{"innerArray": [{"innerMostArray": [{"A1": "A1"}, {"B1": "B1"}]}]}, {"innerArray": [{"innerMostArray": [{"A1": "A1"}, {"B1": "B1"}]}]}]}
(1 row)