JSON_ARRAY_APPEND
Syntax
JSON_ARRAY_APPEND(json_doc, path, value[, path, value] ...)
Description
Appends values to the end of the specified arrays within a JSON document, returning the result, or NULL if any of the arguments are NULL.
Evaluation is performed from left to right, with the resulting document from the previous pair becoming the new value against which the next pair is evaluated.
If the json_doc is not a valid JSON document, or if any of the paths are not valid, or contain a * or ** wildcard, an error is returned.
Examples
SET @json = '[1, 2, [3, 4]]';
SELECT JSON_ARRAY_APPEND(@json, '$[0]', 5)
+-------------------------------------+
| JSON_ARRAY_APPEND(@json, '$[0]', 5) |
+-------------------------------------+
| [[1, 5], 2, [3, 4]] |
+-------------------------------------+
SELECT JSON_ARRAY_APPEND(@json, '$[1]', 6);
+-------------------------------------+
| JSON_ARRAY_APPEND(@json, '$[1]', 6) |
+-------------------------------------+
| [1, [2, 6], [3, 4]] |
+-------------------------------------+
SELECT JSON_ARRAY_APPEND(@json, '$[1]', 6, '$[2]', 7);
+------------------------------------------------+
| JSON_ARRAY_APPEND(@json, '$[1]', 6, '$[2]', 7) |
+------------------------------------------------+
| [1, [2, 6], [3, 4, 7]] |
+------------------------------------------------+
SELECT JSON_ARRAY_APPEND(@json, '$', 5);
+----------------------------------+
| JSON_ARRAY_APPEND(@json, '$', 5) |
+----------------------------------+
| [1, 2, [3, 4], 5] |
+----------------------------------+
SET @json = '{"A": 1, "B": [2], "C": [3, 4]}';
SELECT JSON_ARRAY_APPEND(@json, '$.B', 5);
+------------------------------------+
| JSON_ARRAY_APPEND(@json, '$.B', 5) |
+------------------------------------+
| {"A": 1, "B": [2, 5], "C": [3, 4]} |
+------------------------------------+
Comments
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Hi, Please note that if ANY of the arguments are NULL, JSON_ARRAY_APPEND will return NULL (very dangerous in an UPDATE).
If, for example, the json_doc argument (most likely a column that should contain a JSON object and the column that will likely receive the new JSON object after the append happens) is null, then one can before the append initialize (With set or update) the json_doc with "[]" (an empty and valid JSON object), solving all problems.
SET @json =null; SELECT JSON_ARRAY_APPEND(@json, '$[0]', 5)
the above will not work, but the below will:
SET @json = '[]'; SELECT JSON_ARRAY_APPEND(@json, '$[0]', 5)