# JSON.MERGE Merge a given JSON value into matching paths. Consequently, JSON values at matching paths are updated, deleted, or expanded with new children. This command complies with [RFC7396](https://datatracker.ietf.org/doc/html/rfc7396) Json Merge Patch [Examples](#examples) ## Required arguments

key

is the key to merge into.

path

specifies the JSONPath. For non-existing keys the `path` must be `$`. For existing keys, for each matched `path`, the value that matches the `path` is merged with the JSON `value`. For existing keys, when the path exists, except for the last element, a new child is added with the JSON `value`.

value

is the JSON value to merge with at the specified path. Merging is done according to the following rules per JSON value in the `value` argument while considering the corresponding original value if it exists: * merging an existing object key with a `null` value deletes the key * merging an existing object key with non-null value updates the value * merging a non-existing object key adds the key and value * merging an existing array with any merged value, replaces the entire array with the value

## Return value JSON.MERGE returns a simple string reply: `OK` if executed correctly or `error` if fails to set the new values For more information about replies, see [Redis serialization protocol specification](https://redis.io/docs/latest/develop/reference/protocol-spec). ## Examples JSON.MERGE provides four different behaviors to merge changes on a given key: create a non-existent path, update an existing path with a new value, delete an existing path, or replace an array with a new array

Create a non-existent path-value

redis> JSON.SET doc $ '{"a":2}' OK redis> JSON.MERGE doc $.b '8' OK redis> JSON.GET doc $ "[{\"a\":2,\"b\":8}]"

Replace an existing value

redis> JSON.SET doc $ '{"a":2}' OK redis> JSON.MERGE doc $.a '3' OK redis> JSON.GET doc $ "[{\"a\":3}]"

Delete an existing value

redis> JSON.SET doc $ '{"a":2}' OK redis> JSON.MERGE doc $ '{"a":null}' OK redis> JSON.GET doc $ "[{}]"

Replace an Array

redis> JSON.SET doc $ '{"a":[2,4,6,8]}' OK redis> JSON.MERGE doc $.a '[10,12]' OK redis> JSON.GET doc $ "[{\"a\":[10,12]}]"

Merge changes in multi-paths

redis> JSON.SET doc $ '{"f1": {"a":1}, "f2":{"a":2}}' OK redis> JSON.GET doc "{\"f1\":{\"a\":1},\"f2\":{\"a\":2}}" redis> JSON.MERGE doc $ '{"f1": null, "f2":{"a":3, "b":4}, "f3":[2,4,6]}' OK redis> JSON.GET doc "{\"f2\":{\"a\":3,\"b\":4},\"f3\":[2,4,6]}"

## See also [`JSON.GET`](https://redis.io/docs/latestcommands/json.get/) | [`JSON.MGET`](https://redis.io/docs/latestcommands/json.mget/) | [`JSON.SET`](https://redis.io/docs/latestcommands/json.set/) | [`JSON.MSET`](https://redis.io/docs/latestcommands/json.mset/) ## Related topics * [RedisJSON](https://redis.io/docs/latest/develop/data-types/json/) * [Index and search JSON documents](https://redis.io/docs/latest/develop/interact/search-and-query/indexing/)