HRANDFIELD

Usage:

HRANDFIELD key [ count [ WITHVALUES ] ]

Complexity:

O(N) where N is the number of fields returned

Since:

6.2.0

ACL Categories:

@hash, @read, @slow

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.

Reply

Any of the following:

• Null: if the key doesn't exist
• String: a single, randomly selected field when the count option is not used
• Array containing count fields when the count option is used, or an empty array if the key does not exists.
• Array of fields and their values when count and WITHVALUES were both used.

Examples

127.0.0.1:6379> HSET coin heads obverse tails reverse edge null
(integer) 3
127.0.0.1:6379> HRANDFIELD coin
"heads"
127.0.0.1:6379> HRANDFIELD coin
"heads"
127.0.0.1:6379> HRANDFIELD coin -5 WITHVALUES
 1) "heads"
 2) "obverse"
 3) "tails"
 4) "reverse"
 5) "edge"
 6) "null"
 7) "heads"
 8) "obverse"
 9) "edge"
10) "null"

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.