DB-Transfer 0.5.2

An easy way to fetch and store data from and store to key-value databases like Redis.

DB Transfer

An easy way to manipulate data using key-value databases like Redis.
It is designed to support a number of databases, but currently Redis and yaml file are supported.

INSTALL

pip install DB-Transfer

Design

There are an adapter class for every database.
After instantiating Python Transfer using certain adapter_name, we can manipulate the
data from key-value database just like dictionaries: `transfer[key] = value`

Keys

Keys are created using prefix, namespace and item.
Example: data:USERS:arrrlo:full_name
(data is prefix, USERS is namespace and arrrlo:full_name is item)

Redis Adapter:

Connect to Redis using environment variables

Very handy when using in docker containers.

from db_transfer import Transfer, sent_env

os.environ['REDIS_HOST'] = 'localhost'
os.environ['REDIS_PORT'] = '6379'
os.environ['REDIS_DB'] = '0'

@sent_env('redis', 'HOST', 'REDIS_HOST')
@sent_env('redis', 'PORT', 'REDIS_PORT')
@sent_env('redis', 'DB', 'REDIS_DB')
class RedisTransfer(Transfer):

    def __init__(self, prefix=None, namespace=None):
        super().__init__(prefix=str(prefix), namespace=namespace, adapter_name='redis')

Store data

rt = RedisTransfer()
rt['my_key'] = 'some_string' # redis: "SET" "data:my_key" "some_string"

rt = RedisTransfer(namespace='my_namespace')
rt['my_key'] = 'some_string' # redis: "SET" "data:my_namespace:my_key" "some_string"

rt = RedisTransfer(prefix='my_prefix', namespace='my_namespace')
rt['my_key'] = 'some_string' # redis: "SET" "my_prefix:my_namespace:my_key" "some_string"

Connect to Redis using class parameters

class RedisTransfer(Transfer):

    def __init__(self, prefix, namespace, host, port, db):
        super().__init__(prefix=str(prefix), namespace=namespace, adapter_name='redis')

        self.set_env('HOST', host)
        self.set_env('PORT', port)
        self.set_env('DB', db)

Store data

rt = RedisTransfer(prefix='my_prefix', namespace='my_namespace', host='localhost', port=6379, db=0)

rt['my_key'] = 'some_string' # redis: "SET" "my_prefix:my_name_space:my_key" "some_string"

Fetch data

rt = RedisTransfer(prefix='my_prefix', namespace='my_namespace', host='localhost', port=6379, db=0)

my_var = rt['my_key'] # redis: "GET" "my_prefix:my_namespace:my_key"

Delete data

rt = RedisTransfer(prefix='my_prefix', namespace='my_namespace', host='localhost', port=6379, db=0)

del rt['my_key'] # redis: "DEL" "my_prefix:my_namespace:my_key"

Other data types

rt = RedisTransfer(prefix='my_prefix', namespace='my_namespace', host='localhost', port=6379, db=0)

rt['my_key_1'] = [1,2,3,4] # redis: "RPUSH" "my_prefix:my_namespace:my_key_1" "1" "2" "3" "4"
rt['my_key_2'] = {'foo', 'bar'} # redis: "SADD" "my_prefix:my_namespace:my_key_2" "foo" "bar"
rt['my_key_3'] = {'foo': 'bar'} # redis: "HMSET" "my_prefix:my_namespace:my_key_3" "foo" "bar"

my_var_1 = list(rt['my_key_1']) # redis: "LRANGE" "my_prefix:my_namespace:my_key_1" "0" "-1"
my_var_2 = set(rt['my_key_2']) # redis: "SMEMBERS" "my_prefix:my_namespace:my_key_2"
my_var_3 = dict(rt['my_key_2']) # redis: "HGETALL" "my_prefix:my_namespace:my_key_3"

Redis hash data type

rt = RedisTransfer(prefix='my_prefix', namespace='my_namespace', host='localhost', port=6379, db=0)

rt['my_key'] = {'foo': 'bar'} # redis: "HMSET" "my_prefix:my_namespace:my_key" "foo" "bar"

my_var = dict(rt['my_key']) # redis: "HGETALL" "my_prefix:my_namespace:my_key"
my_var = rt['my_key']['foo'] # redis: "HGET" "my_prefix:my_namespace:my_key" "foo"

rt['my_key']['boo'] = 'doo' # redis: "HSET" "my_prefix:my_namespace:my_key" "boo" "bar"

Multiple commands execution with context manager (only for set and delete)

with RedisTransfer(prefix='my_prefix', namespace='my_namespace', host='localhost', port=6379, db=0) as rt:
    rt['my_key_1'] = 'some_string'
    rt['my_key_2'] = [1,2,3,4]
    rt['my_key_3'] = {'foo': 'bar'}

# redis:
#
# "MULTI"
# "SET" "my_prefix:my_namespace:my_key_1" "some_string"
# "RPUSH" "my_prefix:my_namespace:my_key_2" "1" "2" "3" "4"
# "HMSET" "my_prefix:my_namespace:my_key_3" "foo" "bar"
# "EXEC"

Using iterators

rt = RedisTransfer(prefix='my_prefix', namespace='my_namespace', host='localhost', port=6379, db=0)

for key, value in iter(rt):
    # yields key and value of every key starting with my_prefix:my_namespace:


rt['my_key'] = {...} # saving a hash data (dict)

for key, value in iter(rt['my_key']):
    # yields key and value for every HGET in my_prefix:my_namespace:my_key

Keys

Every key in Redis is stored in set in same Redis.
Example:

rt = RedisTransfer(prefix='my_prefix', namespace='my_namespace', host='localhost', port=6379, db=0)

rt['key_1'] = 'value'
rt['key_2:key3'] = 'value'
rt['key_2:key4'] = 'value'
rt['key_2:key_5:key_6'] = 'value'
rt['key_2:key_5:key_7'] = 'value'
rt['key_2:key_5:key_8'] = 'value'

So, the keys are "key_1", "key_2:key3", "key_2:key4", "key_2:key5:key_6", "key_2:key5:key_7", "key_2:key5:key_8".
They are not stored in one set, but different keys are stored i different sets:
'my_prefix:my_namespace': set({'key_1', 'key_2:keys'})
'my_prefix:my_namespace:key_2': set({'key_3', 'key_4', 'key_5:keys'})
'my_prefix:my_namespace:key_2:key_5': set({'key_6', 'key_7', 'key_8'})

This is done this way so you can easily access data by keys fom any level recursively:

rt.keys()
# > ['key_1', 'key_2:key3', 'key_2:key4', 'key_2:key_5:key_6', 'key_2:key_5:key_7', 'key_2:key_5:key_8']

rt['key_2'].keys()
# > ['key_3', 'key_4', 'key_5:key_6', 'key_5:key_7', 'key_5:key_8']

rt['key_2:key_5'].keys()
# > ['key_6', 'key_7', 'key_8']

Real life examples

Transfer all data from one Redis database to another:

rt_1 = RedisTransfer(prefix='my_prefix', namespace='my_namespace', host='localhost', port=6379, db=0)
rt_2 = RedisTransfer(prefix='my_prefix', namespace='my_namespace', host='some_host', port=6379, db=0)

for key in rt_1.keys():
    rt_2[key] = rt_1[key]

or if you want to insert data in one batch (read goes one by one):

with rt_2:
    for key in rt_1.keys():
        rt_2[key] = rt_1[key]

Transfer data from one user to another:

rt_1 = RedisTransfer(prefix='my_prefix', namespace='my_namespace', host='localhost', port=6379, db=0)

for key in rt_1['arrrlo'].keys():
    rt_1['edi:' + key] = rt_1['arrrlo:' + key]

Delete user from database:

rt_1 = RedisTransfer(prefix='my_prefix', namespace='my_namespace', host='localhost', port=6379, db=0)

with rt_1:
    for key in rt_1['arrrlo'].keys():
        del rt_1['arrrlo:' + key]

Yaml File Adapter:

Initially the data from yaml file transferes from file to memory.
From there every read, write or delete runs until the sync() method
is called. Then the data from memory is transfered to yaml file.
sync() method could be called using context manager or manually.

Define path to yaml file using environment variable

Very handy when using in docker containers.

from db_transfer import Transfer, sent_env

os.environ['YAML_FILE_PATH'] = '/path/to/yaml/file.yaml'

@sent_env('yaml', 'FILE_LOCAL', 'YAML_FILE_PATH')
class YamlFileTransfer(Transfer):

    def __init__(self, prefix=None, namespace=None):
        super().__init__(prefix=str(prefix), namespace=namespace, adapter_name='yaml')

Define path to yaml file using class parameter

class YamlFileTransfer(Transfer):

    def __init__(self, prefix, namespace, yaml_file_path):
        super().__init__(prefix=str(prefix), namespace=namespace, adapter_name='yaml')

        self.set_env('FILE_LOCAL', yaml_file_path)

Write and delete data

Data could be written using context manager or sync() method.

yt = YamlFileTransfer(prefix='my_prefix', namespace='my_namespace', yaml_file_path='/path/')

with yt:
    yt['my_key_1'] = 'some_string'

yt['my_key_2'] = 'some_string'
yt.sync()

with yt:
    del yt['my_key_1']

del yt['my_key_2']
yt.sync()

Real life examples

Backup user data from Redis to yaml file:

rt = RedisTransfer(prefix='my_prefix', namespace='my_namespace', host='localhost', port=6379, db=0)
yt = YamlFileTransfer(prefix='my_prefix', namespace='my_namespace', yaml_file_path='/path/')

for key in rt['arrrlo'].keys():
    yt['arrrlo:' + key] = rt['arrrlo:' + key]

# or (depends on how you use prefix and namespace):

rt = RedisTransfer(prefix='users', namespace='arrrlo', host='localhost', port=6379, db=0)
yt = YamlFileTransfer(prefix='users', namespace='arrrlo', yaml_file_path='/path/')

for key in rt.keys():
    yt[key] = rt[key]

# or:

rt = RedisTransfer(prefix='my_prefix:my_namespace', namespace='arrrlo', host='localhost', port=6379, db=0)
yt = YamlFileTransfer(prefix='my_prefix:my_namespace', namespace='arrrlo', yaml_file_path='/path/')

for key in rt.keys():
    yt[key] = rt[key]

# or:

rt = RedisTransfer(prefix='my_prefix', namespace='my_namespace', host='localhost', port=6379, db=0)
yt = YamlFileTransfer(prefix='my_prefix:my_namespace', namespace='arrrlo', yaml_file_path='/path/')

for key in rt.keys():
    yt[key] = rt['arrrlo:' + key]