HRANDFIELD

Syntax

  1. HRANDFIELD key

Time complexity: O(N) where N is the number of fields returned

When called with just the key argument, return a random field from the hash value stored at key.

If the provided count argument is positive, return an array of distinct fields. The array’s length is either count or the hash’s number of fields (HLEN), whichever is lower.

If called with a negative count, the behavior changes and the command is allowed to return the same field multiple times. In this case, the number of returned fields is the absolute value of the specified count.

The optional WITHVALUES modifier changes the reply so it includes the respective values of the randomly selected hash fields.

Return

Bulk string reply: without the additional count argument, the command returns a Bulk Reply with the randomly selected field, or nil when key does not exist.

Array reply: when the additional count argument is passed, the command returns an array of fields, or an empty array when key does not exist. If the WITHVALUES modifier is used, the reply is a list fields and their values from the hash.

Examples

  1. dragonfly> HMSET coin heads obverse tails reverse edge null
  2. "OK"
  3. dragonfly> HRANDFIELD coin
  4. "heads"
  5. dragonfly> HRANDFIELD coin
  6. "tails"
  7. dragonfly> HRANDFIELD coin -5 WITHVALUES
  8. 1) "edge"
  9. 2) "null"
  10. 3) "tails"
  11. 4) "reverse"
  12. 5) "heads"
  13. 6) "obverse"
  14. 7) "edge"
  15. 8) "null"
  16. 9) "heads"
  17. 10) "obverse"

Specification of the behavior when count is passed

When the count argument is a positive value this command behaves as follows:

  • No repeated fields are returned.
  • If count is bigger than the number of fields in the hash, the command will only return the whole hash without additional fields.
  • The order of fields in the reply is not truly random, so it is up to the client to shuffle them if needed.

When the count is a negative value, the behavior changes as follows:

  • Repeating fields are possible.
  • Exactly count fields, or an empty array if the hash is empty (non-existing key), are always returned.
  • The order of fields in the reply is truly random.