How to store and retrieve a dictionary with redis

# I have the dictionary my_dict
my_dict = {
    'var1' : 5
    'var2' : 9
}
r = redis.StrictRedis()

How would I store my_dict and retrieve it with redis. For example, the following code does not work.

#Code that doesn't work
r.set('this_dict', my_dict)  # to store my_dict in this_dict
r.get('this_dict')  # to retrieve my_dict

Solution 1:

You can do it by hmset (multiple keys can be set using hmset).

hmset("RedisKey", dictionaryToSet)

import redis
conn = redis.Redis('localhost')

user = {"Name":"Pradeep", "Company":"SCTL", "Address":"Mumbai", "Location":"RCP"}

conn.hmset("pythonDict", user)

conn.hgetall("pythonDict")

{'Company': 'SCTL', 'Address': 'Mumbai', 'Location': 'RCP', 'Name': 'Pradeep'}

Solution 2:

you can pickle your dict and save as string.

import pickle
import redis

r = redis.StrictRedis('localhost')
mydict = {1:2,2:3,3:4}
p_mydict = pickle.dumps(mydict)
r.set('mydict',p_mydict)

read_dict = r.get('mydict')
yourdict = pickle.loads(read_dict)

Solution 3:

As the basic answer has already give by other people, I would like to add some to it.

Following are the commands in REDIS to perform basic operations with HashMap/Dictionary/Mapping type values.

1. HGET => Returns value for single key passed
2. HSET => set/updates value for the single key
3. HMGET => Returns value for single/multiple keys passed
4. HMSET => set/updates values for the multiple key
5. HGETALL => Returns all the (key, value) pairs in the mapping.

Following are their respective methods in redis-py library :-

1. HGET => hget
2. HSET => hset
3. HMGET => hmget
4. HMSET => hmset
5. HGETALL => hgetall

All of the above setter methods creates the mapping, if it doesn't exists. All of the above getter methods doesn't raise error/exceptions, if mapping/key in mapping doesn't exists.

Example:
=======
In [98]: import redis
In [99]: conn = redis.Redis('localhost')

In [100]: user = {"Name":"Pradeep", "Company":"SCTL", "Address":"Mumbai", "Location":"RCP"}

In [101]: con.hmset("pythonDict", {"Location": "Ahmedabad"})
Out[101]: True

In [102]: con.hgetall("pythonDict")
Out[102]:
{b'Address': b'Mumbai',
 b'Company': b'SCTL',
 b'Last Name': b'Rajpurohit',
 b'Location': b'Ahmedabad',
 b'Name': b'Mangu Singh'}

In [103]: con.hmset("pythonDict", {"Location": "Ahmedabad", "Company": ["A/C Pri
     ...: sm", "ECW", "Musikaar"]})
Out[103]: True

In [104]: con.hgetall("pythonDict")
Out[104]:
{b'Address': b'Mumbai',
 b'Company': b"['A/C Prism', 'ECW', 'Musikaar']",
 b'Last Name': b'Rajpurohit',
 b'Location': b'Ahmedabad',
 b'Name': b'Mangu Singh'}

In [105]: con.hget("pythonDict", "Name")
Out[105]: b'Mangu Singh'

In [106]: con.hmget("pythonDict", "Name", "Location")
Out[106]: [b'Mangu Singh', b'Ahmedabad']

I hope, it makes things more clear.

Solution 4:

Another way: you can use RedisWorks library.

pip install redisworks

>>> from redisworks import Root
>>> root = Root()
>>> root.something = {1:"a", "b": {2: 2}}  # saves it as Hash type in Redis
...
>>> print(root.something)  # loads it from Redis
{'b': {2: 2}, 1: 'a'}
>>> root.something['b'][2]
2

It converts python types to Redis types and vice-versa.

>>> root.sides = [10, [1, 2]]  # saves it as list in Redis.
>>> print(root.sides)  # loads it from Redis
[10, [1, 2]]
>>> type(root.sides[1])
<class 'list'>

Disclaimer: I wrote the library. Here is the code: https://github.com/seperman/redisworks

Solution 5:

If you want to store a python dict in redis, it is better to store it as json string.

import redis

r = redis.StrictRedis(host='localhost', port=6379, db=0)
mydict = { 'var1' : 5, 'var2' : 9, 'var3': [1, 5, 9] }
rval = json.dumps(mydict)
r.set('key1', rval)

While retrieving de-serialize it using json.loads

data = r.get('key1')
result = json.loads(data)
arr = result['var3']

What about types (eg.bytes) that are not serialized by json functions ?

You can write encoder/decoder functions for types that cannot be serialized by json functions. eg. writing base64/ascii encoder/decoder function for byte array.