Quickstart¶
Below is a sample interactive console session designed to show some of the basic features and functionality of the vedis-python library. Also check out the full API docs.
Key/value features¶
You can use Vedis like a dictionary for simple key/value lookups:
>>> from vedis import Vedis
>>> db = Vedis(':mem:') # Create an in-memory database. Alternatively you could supply a filename for an on-disk database.
>>> db['k1'] = 'v1'
>>> db['k1']
'v1'
>>> db.append('k1', 'more data') # Returns length of value after appending new data.
11
>>> db['k1']
'v1more data'
>>> del db['k1']
>>> db['k1'] is None
True
You can set and get multiple items at a time:
>>> db.mset(dict(k1='v1', k2='v2', k3='v3'))
True
>>> db.mget(['k1', 'k2', 'missing key', 'k3'])
['v1', 'v2', None, 'v3']
In addition to storing string keys/values, you can also implement counters:
>>> db.incr('counter')
1
>>> db.incr('counter')
2
>>> db.incr_by('counter', 10)
12
>>> db.decr('counter')
11
Transactions¶
Vedis has support for transactions when you are using an on-disk database. You can use the transaction()
context manager or explicitly call begin()
, commit()
and rollback()
.
>>> db = Vedis('/tmp/test.db')
>>> with db.transaction():
... db['k1'] = 'v1'
... db['k2'] = 'v2'
...
>>> db['k1']
'v1'
>>> with db.transaction():
... db['k1'] = 'modified'
... db.rollback() # Undo changes.
...
>>> db['k1'] # Value is not modified.
'v1'
>>> db.begin()
>>> db['k3'] = 'v3-xx'
>>> db.commit()
True
>>> db['k3']
'v3-xx'
Hashes¶
Vedis supports nested key/value lookups which have the additional benefit of supporting operations to retrieve all keys, values, the number of items in the hash, and so on.
>>> h = db.Hash('some key')
>>> h['k1'] = 'v1'
>>> h.update(k2='v2', k3='v3')
>>> h
<Hash: {'k3': 'v3', 'k2': 'v2', 'k1': 'v1'}>
>>> h.to_dict()
{'k3': 'v3', 'k2': 'v2', 'k1': 'v1'}
>>> h.items()
[('k1', 'v1'), ('k3', 'v3'), ('k2', 'v2')]
>>> list(h.keys())
['k1', 'k3', 'k2']
>>> del h['k2']
>>> len(h)
2
>>> 'k1' in h
True
>>> [key for key in h]
['k1', 'k3']
Sets¶
Vedis supports a set data-type which stores a unique collection of items.
>>> s = db.Set('some set')
>>> s.add('v1', 'v2', 'v3')
3
>>> len(s)
3
>>> 'v1' in s, 'v4' in s
(True, False)
>>> s.top()
'v1'
>>> s.peek()
'v3'
>>> s.remove('v2')
1
>>> s.add('v4', 'v5')
2
>>> s.pop()
'v5'
>>> [item for item in s]
['v1', 'v3', 'v4']
>>> s.to_set()
set(['v1', 'v3', 'v4'])
>>> s2 = db.Set('another set')
>>> s2.add('v1', 'v4', 'v5', 'v6')
4
>>> s2 & s # Intersection.
set(['v1', 'v4'])
>>> s2 - s # Difference.
set(['v5', 'v6'])
Lists¶
Vedis also supports a list data type.
>>> l = db.List('my list')
>>> l.append('v1')
1
>>> l.extend(['v2', 'v3', 'v1'])
4
>>> for item in l:
... print item
...
v1
v2
v3
v4
>>> for item in l[1:3]:
... print item
v2
v3
>>> len(l)
4
>>> l[1]
'v2'
>>> db.llen('my_list')
2
>>> l.pop(), l.pop()
('v1', 'v2')
>>> len(l)
2
Misc¶
Vedis has a somewhat quirky collection of other miscellaneous commands. Below is a sampling:
>>> db.base64('encode me')
'ZW5jb2RlIG1l'
>>> db.base64_decode('ZW5jb2RlIG1l')
'encode me'
>>> db.random_string(10)
'raurquvsnx'
>>> db.rand(1, 6)
4
>>> db.str_split('abcdefghijklmnop', 5)
['abcde', 'fghij', 'klmno', 'p']
>>> db['data'] = 'abcdefghijklmnop'
>>> db.strlen('data')
16
>>> db.strip_tags('<p>This <span>is</span> a <a href="#">test</a>.</p>')
'This is a test.'