CODEWITHSUNDEEP
mysqlmariadb
Kdigital
Kdigital

Reputation: 3947

How to Update a Specific Object in a JSON Array in Mysql 5.7

How can I update an object in an array based on a unique value in the object? Let's say this is my json object stored in a table called objects and in a column called content

table: objects

    id:  7383    
    content: { data:[{id: 111, active: 1 }, {id: 222, active: 1 }, {id: 333, active: 0 }] }

I can update objects if I know the position of the element in the array with 

SET content = JSON_REPLACE(content,'$.data[1].active', 0)
Where id = 7383

However, if I don't know the position of the array, but I do know the value of id (for example 222) in the object, how can I update active to 0 for the object that has id: 222 ?

Upvotes: 5

Views: 8918

Answers (2)

user07
user07

Reputation: 415

It can be achieved by combining the functions JSON_SEARCH, which returns a dirty json path to the item you need, and then, extract the value of the jsonpath with an array index, concatenate it with subpath we want to update and use JSON_SET to set a new value to the final json path (tested with MySQL 5.7.32):

-- INPUT ------------------------------------------------
-- unique value for an object in the array
SET @unique_value = "12345";

-- object field we want to update
SET @field_to_update = '.myField';

-- new value
SET @new_value = 1;

-- PROCESSING ------------------------------------------
-- Get json path to the item with specified @unique_value
-- RESULT: $.data[6].id
SET @temp_path = ( TRIM(BOTH '"' FROM ( SELECT JSON_SEARCH(json, 'one', @unique_value, NULL, "$.data")
FROM `my-table`
WHERE `column1` = "abcd" ) ));

-- We are looking for the bracket that delimits index within the array of documents: [11]
SET @closing_bracket_index = (SELECT LOCATE(']', @temp_path));

-- Get json path with index of an object for @unique_value
-- in MySQL, string indexing starts from position 1, not a zero
-- RESULT: $.data[6]
SET @item_path = ( SELECT SUBSTRING(@temp_path, 1, @closing_bracket_index) );

-- $.data[6].myFIeld
SET @item_path_to_update = ( SELECT CONCAT(@item_path, @field_to_update) );

-- UPDATE JSON STATEMENT
UPDATE `my-table`
SET json = JSON_SET(json-column, @item_path_to_update, @new_value)
WHERE `column1` = "abcd";

Upvotes: 0

wchiquito
wchiquito

Reputation: 16551

Currently, it's complicated to look up numerical values with MySQL JSON functions. In a JSON like the following, it would be simple:

{"id": "222", "active": 1}

There are many ways to get what you need, I present one that can give you ideas (modify everything that is necessary):

UPDATE `objects`
SET `objects`.`content` = 
  JSON_REPLACE(`objects`.`content`, CONCAT('$.data',
  (SELECT
    JSON_UNQUOTE(
      REPLACE(
        JSON_SEARCH(
          REPLACE(
            REPLACE(
              REPLACE(
                `der`.`content` ->> '$.data[*].id',
                ', ',
                '","'),
              ']',
              '"]'),
          '[',
          '["'),
        'one',
        '222'),
      '$',
      '')
    )
  FROM (SELECT `objects`.`content`
        FROM `objects`
        WHERE `objects`.`id` = 7383) `der`
  ), '.active'), 0)
WHERE `objects`.`id` = 7383;

Beware of possible performance problems.

See dbfiddle.

In the most recent version of MySQL (>= 8.0.4), the sentence would be much simpler:

UPDATE `objects`
  INNER JOIN JSON_TABLE(
    `objects`.`content`,
    '$.data[*]' COLUMNS(
      `rowid` FOR ORDINALITY,
      `id` INT PATH '$.id'
    )
  ) `der` ON `der`.`id` = 222
SET `objects`.`content` =
  JSON_REPLACE(
    `objects`.`content`,
    CONCAT('$.data[', `der`.`rowid` - 1, '].active'),
    0)
WHERE
  `objects`.`id` = 7383;

See db-fiddle.

Upvotes: 1

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