Redis

Example Code

python
import redis

 --- 1. Establish a connection to Redis ---
 Assumes Redis is running on localhost:6379
 Decode_responses=True automatically decodes byte strings to Python strings
r = redis.Redis(host='localhost', port=6379, db=0, decode_responses=True)

print("--- Redis Connection & Basic Operations ---")
try:
     Ping the server to check connection
    if r.ping():
        print("Successfully connected to Redis!")
    else:
        print("Could not connect to Redis.")
        exit()

     --- 2. String Operations ---
    print("\n--- String Operations ---")
     Set a key-value pair
    r.set('mykey', 'Hello Redis!')
    print(f"Set 'mykey' to 'Hello Redis!'")

     Get a key's value
    value = r.get('mykey')
    print(f"Value of 'mykey': {value}")

     Increment a numeric string
    r.set('counter', 0)
    r.incr('counter')  Increments by 1
    r.incr('counter', 5)  Increments by 5
    print(f"Value of 'counter' after increments: {r.get('counter')}")

     --- 3. Hash Operations ---
    print("\n--- Hash Operations ---")
     Set multiple fields in a hash
    r.hset('user:100', mapping={
        'name': 'Alice',
        'email': 'alice@example.com',
        'age': '30'
    })
    print(f"Set hash 'user:100' with name, email, age.")

     Get a specific field from a hash
    user_name = r.hget('user:100', 'name')
    print(f"Name of user 100: {user_name}")

     Get all fields and values from a hash
    user_data = r.hgetall('user:100')
    print(f"All data for user 100: {user_data}")

     --- 4. List Operations ---
    print("\n--- List Operations ---")
     Push elements to the right end of a list (RPUSH)
    r.rpush('mylist', 'item1', 'item2', 'item3')
    print(f"Pushed 'item1', 'item2', 'item3' to 'mylist'.")

     Get all elements from a list (LRANGE)
    list_elements = r.lrange('mylist', 0, -1)
    print(f"Elements in 'mylist': {list_elements}")

     Pop an element from the left end of a list (LPOP)
    popped_item = r.lpop('mylist')
    print(f"Popped from 'mylist': {popped_item}")
    print(f"Remaining elements in 'mylist': {r.lrange('mylist', 0, -1)}")

     --- 5. Set Operations ---
    print("\n--- Set Operations ---")
     Add members to a set (SADD)
    r.sadd('myset', 'apple', 'banana', 'orange')
    r.sadd('myset', 'apple')  Adding existing member has no effect
    print(f"Added 'apple', 'banana', 'orange' to 'myset'.")

     Get all members from a set (SMEMBERS)
    set_members = r.smembers('myset')
    print(f"Members in 'myset': {set_members}")

     Check if a member exists in a set (SISMEMBER)
    is_banana_member = r.sismember('myset', 'banana')
    print(f"Is 'banana' a member of 'myset'? {is_banana_member}")

     --- 6. Publish/Subscribe (Simple Publish Example) ---
    print("\n--- Publish/Subscribe (Simple Publish Example) ---")
     Publish a message to a channel
    channel_name = 'my_updates_channel'
    message = 'New data available!'
     The publish method returns the number of clients that received the message.
    subscribers_count = r.publish(channel_name, message)
    print(f"Published message '{message}' to channel '{channel_name}'. Received by {subscribers_count} client(s).")

except redis.exceptions.ConnectionError as e:
    print(f"Error connecting to Redis: {e}. Please ensure Redis server is running.")
except Exception as e:
    print(f"An unexpected error occurred: {e}")
finally:
     --- Clean up keys (optional, but good practice for examples) ---
     Delete all keys created during the example
    r.delete('mykey', 'counter', 'user:100', 'mylist', 'myset')
    print("\nCleaned up example keys.")