How to turn a json array into rows in postgres

Question

I have a json array stored in my postgres database. The json looks like this:

[
    {
        "operation": "U",
        "taxCode": "1000",
        "description": "iva description",
        "tax": "12"
    },
    {
        "operation": "U",
        "taxCode": "1001",
        "description": "iva description",
        "tax": "12"
    },
    {
        "operation": "U",
        "taxCode": "1002",
        "description": "iva description",
        "tax": "12"
    }
]

Now I need to SELECT the array so that any element is in a different row of the query result. So the SELECT statement I perform must return the data in this way:

 data
--------------------------------------------------------------------------------------
{ "operation": "U", "taxCode": "1000", "description": "iva description", "tax":"12"}
{ "operation": "U", "taxCode": "1001", "description": "iva description", "tax":"12"}
{ "operation": "U", "taxCode": "1002", "description": "iva description", "tax":"12"}

I tried using the unnest() function

SELECT unnest(json_data::json)
FROM my_table

but it doesn't accept the jsonb type.

Answer 1

I post the answer originally written by pozs in the comment section.

unnest() is for PostgreSQL's array types.

Instead one of the following function can be used:

• json_array_elements(json) (9.3+)
• jsonb_array_elements(jsonb) (9.4+)
• json[b]_array_elements_text(json[b]) (9.4+)

Example:

select * from json_array_elements('[1,true, [2,false]]')

output value

 -------------
 | 1         |
 -------------
 | true      |
 -------------
 | [2,false] |
 -------------

Here where the documentation for v9.4 can be found.