Connecting to redis using Python

Introduction#

Connecting to Redis in Python requires the use of a client library. Many different client libraries exist for Python, but redis-py is one of the most popular clients in use.

Once you install your client library, you can then access Redis in your application by importing the appropriate module, establishing a connection, then executing a command.

Remarks#

To connect on redis with python you need to install a client. You can install with pip using:

pip install redis

this will install redis-py

Optionally, you may want to install hiredis-py which delegates parsing of protocol messages to the C hiredis client. This can provide significant performance improvement in many situations. You can install hiredis with pip by executing:

pip install hiredis

Add element to list

import redis

r = redis.StrictRedis(host='localhost', port=6379, db=0)

r.lpush('myqueue','myelement')

Adding fields to a Hash

There are two main functions in Redis (HSET and HMSET) for adding fields to a hash key. Both functions are available in redis-py.

Using HSET:

import redis

r = redis.StrictRedis(host='myserver', port=6379, db=0)
r.hset('my_key', 'field0', 'value0')

Using HMSET:

import redis

r = redis.StrictRedis(host='myserver', port=6379, db=0)
r.hmset('my_key', {'field0': 'value0', 'field1':'value1', 'field2':'value2'}

Setting up a Connection to Redis

The redis-py client provides two classes StrictRedis and Redis to establish a basic connection to a Redis database. The Redis class is provided for backwards compatibility and new projects should use the StrictRedis class.

One of the recommended ways to establish a connection, is to define the connection parameters in a dictionary and pass the dictionary to the StrictRedis constructor using the ** syntax.

conn_params = {
    "host": "myredis.somedomain.com",
    "port": 6379,
    "password": "sekret",
    "db": 0
}

r = redis.StrictRedis(**config)

Creating a transaction

You can establish a transaction by calling the pipeline method on the StrictRedis. Redis commands executed against the transaction are performed in a single block.

# defaults to transaction=True 
tx = r.pipeline()
tx.hincrbyfloat(debit_account_key, 'balance', -amount)
tx.hincrbyfloat(credit_account_key, 'balance', amount)
tx.execute()

Executing Commands Directly

Redis-py provides the execute_command method to directly invoke Redis operations. This functionality can be used to access any modules that may not have a supported interface in the redis-py client. For example, you can use the execute_command to list all of the modules loaded into a Redis server:

r.execute_command('MODULE', 'LIST')