JSON.ARRLEN - Amazon MemoryDB for Redis
Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

JSON.ARRLEN

Get length of the array values at the path.

Syntax

JSON.ARRLEN <key> [path]
  • key (required) – Redis key of JSON document type

  • path (optional) – a JSON path. Defaults to the root if not provided

Return

If the path is enhanced syntax:

  • Array of integers, representing the array length at each path.

  • If a value is not an array, its corresponding return value is null.

  • Null if the document key does not exist.

If the path is restricted syntax:

  • Array of bulk strings. Each element is a key name in the object.

  • Integer, array length.

  • If multiple objects are selected, the command returns the first array's length.

  • WRONGTYPE error if the value at the path is not an array.

  • WRONGTYPE error if the path does not exist.

  • Null if the document key does not exist.

Examples

Enhanced path syntax:

127.0.0.1:6379> JSON.SET k1 . '[[], [\"a\"], [\"a\", \"b\"], [\"a\", \"b\", \"c\"]]' (error) SYNTAXERR Failed to parse JSON string due to syntax error 127.0.0.1:6379> JSON.SET k1 . '[[], ["a"], ["a", "b"], ["a", "b", "c"]]' OK 127.0.0.1:6379> JSON.ARRLEN k1 $[*] 1) (integer) 0 2) (integer) 1 3) (integer) 2 4) (integer) 3 127.0.0.1:6379> JSON.SET k2 . '[[], "a", ["a", "b"], ["a", "b", "c"], 4]' OK 127.0.0.1:6379> JSON.ARRLEN k2 $[*] 1) (integer) 0 2) (nil) 3) (integer) 2 4) (integer) 3 5) (nil)

Restricted path syntax:

127.0.0.1:6379> JSON.SET k1 . '[[], ["a"], ["a", "b"], ["a", "b", "c"]]' OK 127.0.0.1:6379> JSON.ARRLEN k1 [*] (integer) 0 127.0.0.1:6379> JSON.ARRLEN k1 $[3] 1) (integer) 3 127.0.0.1:6379> JSON.SET k2 . '[[], "a", ["a", "b"], ["a", "b", "c"], 4]' OK 127.0.0.1:6379> JSON.ARRLEN k2 [*] (integer) 0 127.0.0.1:6379> JSON.ARRLEN k2 $[1] 1) (nil) 127.0.0.1:6379> JSON.ARRLEN k2 $[2] 1) (integer) 2