Python Language Tutorial => Creating a new Shelf

Example

The simplest way to use shelve is via the DbfilenameShelf class. It uses anydbm to store the data. You can use the class directly, or simply call shelve.open():

import shelve

s = shelve.open('test_shelf.db')
try:
    s['key1'] = { 'int': 10, 'float':9.5, 'string':'Sample data' }
finally:
    s.close()

To access the data again, open the shelf and use it like a dictionary:

    import shelve
    
    s = shelve.open('test_shelf.db')
    try:
        existing = s['key1']
    finally:
        s.close()

print existing

If you run both sample scripts, you should see:

$ python shelve_create.py
$ python shelve_existing.py

{'int': 10, 'float': 9.5, 'string': 'Sample data'}

The dbm module does not support multiple applications writing to the same database at the same time. If you know your client will not be modifying the shelf, you can tell shelve to open the database read-only.

import shelve

s = shelve.open('test_shelf.db', flag='r')
try:
    existing = s['key1']
finally:
    s.close()

print existing

If your program tries to modify the database while it is opened read-only, an access error exception is generated. The exception type depends on the database module selected by anydbm when the database was created.

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Python Language shelve Creating a new Shelf

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