How to remove nulls JSON object in PostgreSQL®?

- 2 minutes read - 386 words

PostgreSQL® offers two types of data types to handle JSON data, JSON and JSONB, you can use the json_strip_nulls (jsonb_strip_nulls for JSONB) function to remove the null values.

NOTE: To review the differences between JSON and JSONB check out the related article.

NOTE: more info is available in the PostgreSQL JSON functions documentation page

 

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The dataset

The dataset is the following:

{
    "id": 778,
    "shop": "Luigis Pizza",
    "name": "Edward Olson",
    "phoneNumbers":
        ["(935)503-3765x4154","(935)12345"],
    "address": "Unit 9398 Box 2056\nDPO AP 24022",
    "image": null,
    "pizzas": [
        {
            "pizzaName": "Salami",
            "additionalToppings": ["🥓", "🌶️"]
        },
        {
            "pizzaName": "Margherita",
            "additionalToppings": ["🍌", "🌶️", "🍍"]
        }
    ]
}
Check out the description of the fields The following examples use a pizza order dataset with an order having:
  • id: 778
  • shop: “Luigis Pizza”
  • name: “Edward Olson”
  • phoneNumbers:["(935)503-3765x4154","(935)12345"]
  • address: “Unit 9398 Box 2056\nDPO AP 24022”
  • image: null
  • and two pizzas contained in the pizzas item:
[
    {
        "pizzaName": "Salami",
        "additionalToppings": ["🥓", "🌶️"]
    },
    {
        "pizzaName": "Margherita",
        "additionalToppings": ["🍌", "🌶️", "🍍"]
    }
]
If you want to reproduce the examples, check how to recreate the dataset

It can be recreated with the following script:

create table test(id serial, json_data jsonb);

insert into test(json_data) values (
'{
    "id": 778,
    "shop": "Luigis Pizza",
    "name": "Edward Olson",
    "phoneNumbers":
        ["(935)503-3765x4154","(935)12345"],
    "address": "Unit 9398 Box 2056\nDPO AP 24022",
    "image": null,
    "pizzas": [
        {
            "pizzaName": "Salami",
            "additionalToppings": ["🥓", "🌶️"]
        },
        {
            "pizzaName": "Margherita",
            "additionalToppings": ["🍌", "🌶️", "🍍"]
        }
    ]
}');

Remove the null values with the json_strip_nulls function

Null values in a JSON object can be removed using the json_strip_nulls (jsonb_strip_nulls in the example since the column is JSONB) function.

select 
    jsonb_strip_nulls(json_data) no_nulls
from test;

Result, the images field has been removed since it has a null value

                                                                                                                                                    no_nulls
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 {"id": 778, "name": "Edward Olson", "shop": "Luigis Pizza", "pizzas": [{"pizzaName": "Salami", "additionalToppings": ["🥓", "🌶️"]}, {"pizzaName": "Margherita", "additionalToppings": ["🍌", "🌶️", "🍍"]}], "address": "Unit 9398 Box 2056\nDPO AP 24022", "phoneNumbers": ["(935)503-3765x4154", "(935)12345"]}
(1 row)

Review all the JSON PostgreSQL use-cases listed in the main page