How to Use HKEYS Command in Redis: Syntax and Examples

In Redis, use the HKEYS command to retrieve all the field names (keys) stored in a hash. The command syntax is HKEYS key, where key is the name of the hash. It returns a list of all fields inside that hash.

Syntax

The HKEYS command syntax is simple:

• HKEYS key: Returns all field names in the hash stored at key.

If the hash does not exist, it returns an empty list.

redis

HKEYS myhash

Output

1) "field1"
2) "field2"
3) "field3"

Example

This example shows how to create a hash and then use HKEYS to get all its fields.

redis

127.0.0.1:6379> HSET myhash field1 "Hello"
(integer) 1
127.0.0.1:6379> HSET myhash field2 "World"
(integer) 1
127.0.0.1:6379> HSET myhash field3 "!"
(integer) 1
127.0.0.1:6379> HKEYS myhash

Output

1) "field1"
2) "field2"
3) "field3"

Common Pitfalls

Common mistakes when using HKEYS include:

• Using HKEYS on a key that is not a hash, which returns an error.
• Expecting HKEYS to return values instead of field names.
• Not handling the case when the hash key does not exist, which returns an empty list.

redis

127.0.0.1:6379> SET mystring "value"
OK
127.0.0.1:6379> HKEYS mystring
(error) WRONGTYPE Operation against a key holding the wrong kind of value

-- Correct usage:
127.0.0.1:6379> HKEYS myhash
1) "field1"
2) "field2"
3) "field3"

Quick Reference

HKEYS Command Summary:

Command	Description	Returns
HKEYS key	Get all field names in the hash stored at key	Array of field names
HGET key field	Get value of a specific field	Value string or nil
HSET key field value	Set field in hash to value	1 if new field, 0 if updated
DEL key	Delete the key	1 if deleted, 0 if not found

Key Takeaways

Use HKEYS to get all field names from a Redis hash key.

HKEYS returns an empty list if the hash does not exist.

Do not use HKEYS on keys that are not hashes to avoid errors.

HKEYS returns only field names, not their values.

Combine HKEYS with HGET to retrieve values for each field.