Sets the value of a field in a hash only when the field doesn’t exist.
HSETNX key field value
Sets field in the hash stored at key to value, only if field does not yet exist. If key does not exist, a new key holding a hash is created. If field already exists, this operation has no effect.
One of the following:
Integer reply: 0 if the field already exists in the hash and no operation was performed.
Integer reply: 1 if the field is a new field in the hash and the value was set.
O(1)
@fast @hash @write
127.0.0.1:6379> HSETNX myhash field "Hello"
(integer) 1
127.0.0.1:6379> HSETNX myhash field "World"
(integer) 0
127.0.0.1:6379> HGET myhash field
"Hello"HDEL, HEXISTS, HGET, HGETALL, HINCRBY, HINCRBYFLOAT, HKEYS, HLEN, HMGET, HRANDFIELD, HSCAN, HSET, HSTRLEN, HVALS.