Adding key-value pairs to BerkeleyDB using hash access method

Question

I am trying to create a BerkeleyDB using the hash access method, like so:

>>> from bsddb3 import db
>>> dben = DB()
>>> dben.open("filename", None, db.DB_HASH, db.DB_CREATE)

However, when I try to insert an entry, nothing works:

>>> dben.put(3,2)

results in

Traceback (most recent call last): File "", line 1, in dben.put(3,2) TypeError: Integer keys only allowed for Recno and Queue DB's

Attempting

>>> dben[2] = 1

it gives the same error.

How do I add an entry to my hash BerkeleyDB?

Using cntrl-space for autocomplete I can see no relevant methods. The same goes for the docs: PyBSDDB v5.3.0 documentation

score 1 · Accepted Answer · edited Dec 17 '15 at 20:18

1

The only (ugly) workaround on Python 3+ is to encode string to bytes first:

dben.put(bytes(str(3), "ascii"), bytes(str(2), "ascii"))

or, more conveniently:

dben.put(str(3).encode("ascii"), str(2).encode("ascii"))

>>> dben.exists(bytes(2, "ascii"))
False
>>> dben.exists(bytes(3, "ascii"))
True

edited Dec 17 '15 at 20:18

cyberj0g

answered Nov 20 '12 at 11:13

The Unfun Cat

Be careful, bytes(n) where n is integer creates byte array of length n, it doesn't convert n to bytes! Edited your answer. – cyberj0g Dec 17 '15 at 20:19

score 1 · Answer 2 · answered Feb 28 '16 at 10:32

1

bsddb stores as key and value only bytes. So you have to convert your value to bytes first. The prefered method is to use the struct python module.

answered Feb 28 '16 at 10:32

amirouche

2 Answers2