A list preserves the order of elements and supports access by index. This makes it suitable for tasks such as creating task queues, logging events, or storing real-time data like recent user activities.

The Main Commands for Working With Lists in Redis

The key commands for working with lists in Redis include several categories, each addressing a specific task: adding, retrieving, reading, modifying, deleting elements, and managing the list's size.

Adding Elements to a List

Redis provides two commands for adding elements to a list: LPUSH and RPUSH, which add elements to the beginning and the end of the list, respectively.

LPUSH tasks "Task1" "Task2"  # adds to the beginning
RPUSH tasks "Task3" "Task4"  # adds to the end

After executing these commands, the tasks list will look like this: ["Task2", "Task1", "Task3", "Task4"].

Removing Elements from a List

To remove elements from a list, Redis provides two commands: LPOP and RPOP, which remove and return elements from the beginning and the end of the list, respectively.

LPOP tasks  # removes and returns "Task2"
RPOP tasks  # removes and returns "Task4"

After executing these commands, the tasks list will look like this: ["Task1", "Task3"].

Reading Elements from a List

To read elements from a list, Redis offers the commands LRANGE, LINDEX, and LLEN. LRANGE and LINDEX allow you to retrieve elements by index, while LLEN returns the total number of elements in the list.

LRANGE tasks 0 -1  # returns all elements in the list
LINDEX tasks 0    # returns the first element
LLEN tasks        # returns the length of the list

• LRANGE will return all elements: ["Task1", "Task3"];
• LINDEX will return "Task1";
• LLEN will return 2.

Modifying a List

To modify an element in a list, use the LSET command, which allows you to update an element at a specific index.

LSET tasks 1 "UpdatedTask"  # updates the second element to "UpdatedTask"

After executing this command, the tasks list will be: ["Task1", "UpdatedTask"].

Trimming a List

The LTRIM command is used to trim a list, keeping only the elements within a specified range. All other elements will be removed.

LTRIM tasks 0 1  # keeps only the first two elements

If the tasks list was: ["Task1", "Task2", "Task3"], after executing the command, the list will contain: ["Task1", "Task2"].