HSTRLEN

The HSTRLEN command in DiceDB is used to obtain the string length of value associated with field in the hash stored at a specified key.

Syntax

HSTRLEN key field

Parameters

Parameter	Description	Type	Required
key	The key of the hash, which consists of the field whose string length you want to obtain	String	Yes
field	The field present in the hash whose length you want to obtain	String	Yes

Return Value

Condition	Return Value
If specified key and field exists	string length
If key doesn’t exist	0
If field doesn’t exist	0

Behaviour

• DiceDB checks if the specified key exists.
• If the key exists, is associated with a hash and specified field exists in the hash, DiceDB returns the string length of value associated with specified field in the hash.
• If the key does not exist, DiceDB returns 0.
• If the key exists and specified field does not exist in the key, DiceDB returns 0.

Errors

1. Wrong type of key:

   • Error Message: (error) WRONGTYPE Operation against a key holding the wrong kind of value
   • Occurs when attempting to use the command on a key that contains a non-hash value.

2. Wrong number of arguments:

   • Error Message: (error) -ERR wrong number of arguments for 'hstrlen' command
   • Occurs if key or field isn’t specified in the command.

Example Usage

Basic Usage

Creating hash myhash with two fields field1 and field2. Getting string length of value in field1.

127.0.0.1:7379> HSET myhash field1 "helloworld" field2 "value2"
(integer) 1

127.0.0.1:7379> HSTRLEN myhash field1
(integer) 10

Invalid Usage on non-existent key

Getting string length from a non-existent key nonExistentHash.

127.0.0.1:7379> HSTRLEN nonExistentHash field1
(integer) 0

Invalid Usage on non-hash key

Getting string length from a key mystring associated with a non-hash type.

127.0.0.1:7379> SET mystring "This is a string"
OK

127.0.0.1:7379> HSTRLEN mystring field1
(error) WRONGTYPE Operation against a key holding the wrong kind of value

Notes

• The HSTRLEN command has a constant-time operation, meaning its execution time is O(1), regardless of the number of fields in the hash.