How to Use HLEN Command in Redis to Get Hash Field Count

Use the HLEN command in Redis to get the number of fields stored in a hash. It returns an integer representing how many key-value pairs the hash contains.

Syntax

The HLEN command syntax is simple. You provide the key name of the hash, and Redis returns the count of fields inside that hash.

• HLEN key: Returns the number of fields in the hash stored at key.

redis

HLEN myhash

Example

This example shows how to create a hash, add fields, and then use HLEN to get the number of fields in that hash.

redis

HSET myhash field1 "Hello"
HSET myhash field2 "World"
HLEN myhash

Output

2

Common Pitfalls

One common mistake is using HLEN on a key that does not exist or is not a hash. In such cases, Redis returns 0 or an error respectively.

Also, remember that HLEN counts fields, not the total size or length of values.

redis

HLEN nonexistingkey
# Returns 0 because the key does not exist

SET notahash "value"
HLEN notahash
# Returns an error because the key is not a hash

Output

0
(error) WRONGTYPE Operation against a key holding the wrong kind of value

Quick Reference

Command	Description
HLEN key	Returns the number of fields in the hash stored at key
HSET key field value	Sets the value of a field in the hash
HGET key field	Gets the value of a field in the hash
DEL key	Deletes the key and its hash

Key Takeaways

HLEN returns the count of fields in a Redis hash key.

If the key does not exist, HLEN returns 0.

Using HLEN on a non-hash key causes an error.

HLEN counts fields, not the size of values.

Use HSET to add fields before using HLEN.