JSON.ARRINSERT

Introduction and Use Case(s)

JSON.ARRINSERT is a command in Redis used for inserting elements into a JSON array at a specified index. It is particularly useful when you need to dynamically modify JSON data stored in Redis, allowing for the painless insertion of new elements without rewriting the entire array.

Syntax

JSON.ARRINSERT <key> <path> <index> <json>

Parameter Explanations

• <key>: The key under which the JSON document is stored.
• <path>: The path in the JSON document where the array resides.
• <index>: The index at which to insert the new element. If the index is negative, it counts from the end of the array.
• <json>: The JSON element to insert into the array.

Return Values

The command returns the length of the array after the insertion.

(integer) 4

If the path does not exist or is not an array, the command will return (integer) -1.

Code Examples

dragonfly> JSON.SET myjson . '{"name": "Alice", "hobbies": ["reading", "swimming"]}'
OK
dragonfly> JSON.ARRINSERT myjson $.hobbies 1 '"coding"'
(integer) 3
dragonfly> JSON.GET myjson
{"name":"Alice","hobbies":["reading","coding","swimming"]}

Here, the "coding" hobby is inserted at index 1 in the hobbies array.

Best Practices

• Always ensure that the path provided points to an array within the JSON document.
• Validate the JSON structure before performing operations to avoid unexpected results.

Common Mistakes

• Specifying a non-array path: The command will fail if the path does not point to an array.
• Incorrect JSON format: Ensure the JSON string provided as the element is correctly formatted.

FAQs

What happens if I use a negative index?

A negative index counts from the end of the array, with -1 being the last element.

Can I insert multiple elements at once?

No, JSON.ARRINSERT inserts only one element at a time. To insert multiple elements, you need to call the command multiple times.