Postgres - query json with nested arrray and objects inside array

Question

I have data stored in a Postgres 12 table as jsonb, the structure of the jsonb has an array inside an array.

How do i get the values from the nested array? I can get the values from the first level array but not the second level array.

This is a simplified example of the json

{
    "id": 1,
    "external_order_id": {
        "id": "2"
    },
    "customer": {
        "external_customer_id": {
            "id": "3"
        }
    },
    "line_items": [
        {
            "sku": "SKU-1",
            "properties": [
                {
                    "name": "colour",
                    "value": "red"
                },
                {
                    "name": "size",
                    "value": "large"
                }
            ],
            "external_product_id": {
                "id": "4"
            },
            "external_variant_id": {
                "id": "5"
            }
        },
        {
            "sku": "SKU-2",
            "properties": [
                {
                    "name": "colour",
                    "value": "black"
                },
                {
                    "name": "size",
                    "value": "small"
                }
            ],
            "external_product_id": {
                "id": "8"
            },
            "external_variant_id": {
                "id": "9"
            }
        }
    ]
}

using jsonb_to_record and jsonb_to_recordset with LATERAL and CROSS JOIN LATERAL, i am able to get the values from the nodes and the first level array

WITH data(content) AS ( VALUES
  ('{
    "id": 1,
         "external_order_id": {
        "id": "2"
    },
    "customer": {
        
        "external_customer_id": {
            "id": "3"
        }
    },
    "line_items": [
        {
            "sku": "SKU-1",
            "properties": [
                {
                    "name": "colour",
                    "value": "red"
                },
                {
                    "name": "size",
                    "value": "large"
                }
            ],
            "external_product_id": {
                "id": "4"
            },
            "external_variant_id": {
                "id": "5"
            }
        },
                {
            "sku": "SKU-2",
            "properties": [
                {
                    "name": "colour",
                    "value": "black"
                },
                {
                    "name": "size",
                    "value": "small"
                }
            ],
            "external_product_id": {
                "id": "8"
            },
            "external_variant_id": {
                "id": "9"
            }
        }
    ]
   
}'::jsonb)
)
select ord.*
,ext.id as external_order_id
,cus.id as external_customer_id
,line_items.*

FROM data,
jsonb_to_record(content) as ord(id int),
LATERAL jsonb_to_record(content->'external_order_id') as ext(id text),
LATERAL jsonb_to_record(content#>'{customer, external_customer_id}') as cus(id text)
CROSS JOIN LATERAL jsonb_to_recordset(content->'line_items') line_items(sku text)

This is the result so far

| id | external_order_id | external_customer_id | sku   |
|----|-------------------|----------------------|-------|
| 1  | 2                 | 3                    | SKU-1 |
| 1  | 2                 | 3                    | SKU-2 |

what i want to achieve is. ideally this would be achieved without knowing the values of the property names

| id | external_order_id | external_customer_id | sku   | external_product_id | external_variant_id | property_name | property_value |
|----|-------------------|----------------------|-------|---------------------|---------------------|---------------|----------------|
| 1  | 2                 | 3                    | SKU-1 | 4                   | 5                   | colour        | red            |
| 1  | 2                 | 3                    | SKU-1 | 4                   | 5                   | size          | large          |
| 1  | 2                 | 3                    | SKU-2 | 8                   | 9                   | colour        | black          |
| 1  | 2                 | 3                    | SKU-2 | 8                   | 9                   | size          | small          |

dbfiddle

Cetin Basoz · Accepted Answer · 2021-12-10 21:06:28Z

WITH data(content) AS ( VALUES
  ('{
    "id": 1,
         "external_order_id": {
        "id": "2"
    },
    "customer": {

        "external_customer_id": {
            "id": "3"
        }
    },
    "line_items": [
        {
            "sku": "SKU-1",
            "properties": [
                {
                    "name": "colour",
                    "value": "red"
                },
                {
                    "name": "size",
                    "value": "large"
                }
            ],
            "external_product_id": {
                "id": "4"
            },
            "external_variant_id": {
                "id": "5"
            }
        },
                {
            "sku": "SKU-2",
            "properties": [
                {
                    "name": "colour",
                    "value": "black"
                },
                {
                    "name": "size",
                    "value": "small"
                }
            ],
            "external_product_id": {
                "id": "8"
            },
            "external_variant_id": {
                "id": "9"
            }
        }
    ]

}'::jsonb)
)
select ord.*
,ext.id as external_order_id
,cus.id as external_customer_id
,line_items.sku
,line_items.external_product_id->>'id' as external_product_id
,line_items.external_variant_id->>'id' as external_variant_id
,props.*
FROM data,
jsonb_to_record(content) as ord(id int),
LATERAL jsonb_to_record(content->'external_order_id') as ext(id text),
LATERAL jsonb_to_record(content#>'{customer, external_customer_id}') as cus(id text)
CROSS JOIN LATERAL jsonb_to_recordset(content->'line_items') line_items(sku text, properties jsonb, external_product_id jsonb, external_variant_id jsonb)
cross join LATERAL jsonb_to_recordset(line_items.properties) props(name text, value text)

Perfect, thank you. i had found a post that suggested you could pass results down to the next lateral join, but i couldn't quite figure out the syntax. It looks so obvious once you see the answer

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