I'm using python 2.7.3 and and Berkeley DB to store data. I didn't find much information about that module, only in python docks. I saw there some function described, but I didn't see instruction on how to delete a record from database. Help please, if you know how to delete a record and is that possible using bsddb ?
1 Answer
According to the documentation:
Once instantiated, hash, btree and record objects support the same methods as dictionaries.
So, you can use del db_object['key'] to delete specific record like a dictionary.
>>> import bsddb
>>> db = bsddb.hashopen('a.db', 'c')
>>> db['a'] = '1'
>>> db.keys()
['a']
>>> del db['a'] # <-----
>>> db.keys()
[]
db_object.pop('key') also works.
>>> db['b'] = '2'
>>> db.keys()
['b']
>>> db.pop('b')
'2'
del, .pop() with non-existing key will raise KeyError or similar exception. If you want ignore non-existing key, use .pop('key', None):
>>> db.pop('b') # This raises an exception
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python2.7/_abcoll.py", line 497, in pop
value = self[key]
File "/usr/lib/python2.7/bsddb/__init__.py", line 270, in __getitem__
return _DeadlockWrap(lambda: self.db[key]) # self.db[key]
File "/usr/lib/python2.7/bsddb/dbutils.py", line 68, in DeadlockWrap
return function(*_args, **_kwargs)
File "/usr/lib/python2.7/bsddb/__init__.py", line 270, in <lambda>
return _DeadlockWrap(lambda: self.db[key]) # self.db[key]
KeyError: 'b'
>>> db.pop('b', None) # This does not.
>>>
