如何从 Postgres 中的 JSON 数组中删除 JSON 对象？

Question

I am new to Postgres. I want to delete the JSON object from the JSON array.

I have a table where I am using jsonb column in that I am storing JSON array as like below.

[
  {
    "id": "c75e7a-001e-4d64-9613-62f666d42103",
    "name": "Product1"
  },
  {
    "id": "c75e7a-001e-4d64-9613-62f666d42103",
    "name": null
  },
  {
    "id": "c75e7a-001e-4d64-9613-62f666d42103",
    "name": "Product2"
  },
  {
    "id": "c75e7a-001e-4d64-9613-62f666d42103",
    "name": null
  }
]

I want to remove JSON objects from an array that contains a null value in the name key.

after removing answer should be like this

[
  {
    "id": "c75e7a-001e-4d64-9613-62f666d42103",
    "name": "Product1"
  },
  {
    "id": "c75e7a-001e-4d64-9613-62f666d42103",
    "name": "Product2"
  }
]

anyone, please help me to write the SQL query,

I know how to get all the records from the table which contains the null value.

SELECT * 
  FROM table_name 
 WHERE jsonb_col_name @>CAST('[{"name": null}]' AS JSONB);

But I don't know how to make a delete query please help me with this. How Can I do it using a query?

Answer 1

Unnest the array with jsonb_array_elements , exclude the null values with a FILTER and aggregate them again eg

SELECT 
  jsonb_agg(j) FILTER (WHERE j->>'name' IS NOT NULL)
FROM table_name t, jsonb_array_elements(jsonb_col) j 
GROUP BY t.jsonb_col;

Demo: db<>fiddle

Answer 2

You can filter out by j.value ->> 'name' IS NOT NULL after splitting the array into sub-objects by using JSONB_ARRAY_ELEMENTS and then apply JSONB_AGG in order to convert it back to an array such as

SELECT JSONB_PRETTY(
                    JSONB_AGG(j)
                   )
  FROM t, 
       JSONB_ARRAY_ELEMENTS(json_data) AS j
 WHERE j.value ->> 'name' IS NOT NULL
 GROUP BY json_data

If needed to update the existing data, then you might consider using

WITH tt AS
(
SELECT JSONB_AGG(j) AS new_val,
       json_data            
  FROM t, 
       JSONB_ARRAY_ELEMENTS(json_data) AS j
 WHERE j.value ->> 'name' IS NOT NULL
 GROUP BY json_data
)
UPDATE t
   SET json_data = new_val::JSONB
  FROM tt
 WHERE t.json_data = tt.json_data

Demo

Answer 3

You can use json_array_elements :

select json_agg(i.value) from json_array_elements('[{"id": "c75e7a-001e-4d64-9613-62f666d42103", "name": "Product1"}, {"id": "c75e7a-001e-4d64-9613-62f666d42103", "name": null}, {"id": "c75e7a-001e-4d64-9613-62f666d42103", "name": "Product2"}, {"id": "c75e7a-001e-4d64-9613-62f666d42103", "name": null}]') v 
where (v.value -> 'name')::text != 'null'

Output:

[{"id": "c75e7a-001e-4d64-9613-62f666d42103", "name": "Product1"}, {"id": "c75e7a-001e-4d64-9613-62f666d42103", "name": "Product2"}]