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DiceDB

TYPE

The TYPE command in DiceDB is used to determine the data type of the value stored at a specified key. This command is useful when you need to verify the type of data associated with a key before performing operations on it. It aids in debugging and helps ensure that the correct commands are used for different data types.

Syntax

Terminal window
TYPE key

Parameters

ParameterDescriptionTypeRequired
keyThe key to check for its value typeStringYes

Return values

ConditionReturn Value
Key existsThe type of the value stored at the key (string, list, set, zset, hash, stream)
Key does not exist”none”

Behaviour

  • The TYPE command examines the value stored at the specified key and returns its data type.
  • If the key does not exist, the command returns “none”.
  • The command does not modify the value or the key in any way; it’s a read-only operation.
  • The time complexity of this command is O(1), making it efficient for frequent use.

Errors

  1. Wrong number of arguments:
    • Error Message: (error) ERR wrong number of arguments for 'type' command
    • Occurs when the TYPE command is called without specifying a key or more than 1 arguement.

Example Usage

Basic Usage

Terminal window
127.0.0.1:7379> SET mykey "Hello"
OK
127.0.0.1:7379> TYPE mykey
string

Checking Different Data Types

Terminal window
127.0.0.1:7379> LPUSH mylist "element"
(integer) 1
127.0.0.1:7379> TYPE mylist
list


127.0.0.1:7379> SADD myset "element"
(integer) 1
127.0.0.1:7379> TYPE myset
set


127.0.0.1:7379> ZADD myzset 1 "element"
(integer) 1
127.0.0.1:7379> TYPE myzset
zset


127.0.0.1:7379> HSET myhash field value
(integer) 1
127.0.0.1:7379> TYPE myhash
hash


127.0.0.1:7379> GEOADD mygeo 13.361389 38.115556 "Palermo"
(integer) 1
127.0.0.1:7379> TYPE mygeo
zset


127.0.0.1:7379> SET key1 foobar
OK
127.0.0.1:7379> SET key2 abcdef
OK
127.0.0.1:7379> BITOP AND dest key1 key2
(integer) 6
127.0.0.1:7379> TYPE dest
string

Non-existent Key

Terminal window
127.0.0.1:7379> TYPE nonexistentkey
none

Best Practices

  • Use the TYPE command before performing operations on a key to ensure you are using the appropriate commands for the data type.
  • Remember that TYPE returns “none” for non-existent keys, which can be useful for checking key existence without modifying data.

Notes

  • The TYPE command is particularly useful in debugging scenarios where you need to verify the structure of your data.
  • While TYPE is efficient (O(1) complexity), avoid overusing it in high-performance scenarios where you already know the data types of your keys.
  • The TYPE command can be used in combination with other commands to create more robust and type-safe operations in your applications.