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propdb 0.3.0

Property Bag Style Database

Description

The propdb package is a simple database package. It is basically a persisting Python dictionary.

Property item name’s are dictionary keys and the dictionary values are property items. The keys are enforced to be of basestring type whereas the values can be anything, almost. The property bag is saved to the file system by serializing the dictionary as JSON or by cPickle; therefore, the property item values must be able to be seriailized by one of those two modules.

Property bag name and location form the path where the bag is saved. If no location is set then the current working directory is used. If no name is set then a temp name is automatically generated. Property bags are created by instantiating a propbag. Property items are created by calling add from the bag instance.

If autosave is true then the bag will automatically save when property items are added, updated, or dropped. If multiple items need to be added, updated, or dropped then suspend autosave before operations by calling suspend_autosave(). Resume autosaving once operations are completed by calling resume_autosave(). If autosave is false then the bag can manually be saved by calling the save() method. Checking the is_dirty property on the bag indicates if the bag needs to be saved.

Property items in a property bag can be iterated directly on the instance of the bag (e.g. for item in bag).

Property bags can be serialized as JSON or by cPickle by setting the “backend” argument when instantiating a bag.

Property bags can be encrypted by setting the secret_key argument. The secret_key can be 32 characters in length and AES encryption algorithm is used. Note: The M2Crypto must be installed for this feature to work.

Property bags can be sync’d if multiple instances of the same bag is referenced by other property bags by calling the sync() method. If autosync is set to true when instantiating a property bag then sync’ing will automatically be done when saving.

Installation

pip install propdb

Basic Usage

from propdb.propbag import propbag as bag
from propdb.propbag import propitem as item

bag1 = bag('bag1')
bag1.add('item1')
bag1.add(('item2', 'Value as a string', 'item3', 3333))

item1 = bag1['item1']
item1.value = [1, 2, 3, 4]
bag1.set(item1)

bag1.set(('item2', 'A new string value'))
bag1.set({'item3':12345})

Imports

from propdb.propbag import propbag
from propdb.propbag import propitem

Create a new property bag

# all arguments are optional
propbag(name, directory, autosave, backend, secret_key)

# creates a bag with a random name
bag1 = propbag()

# creates a bag named 'mybag' in the current working directory
bag2 = propbag('mybag')

# creates a bag named 'mybag' in the temp folder
bag3 = propbag('mybag', 'c:\\temp')

# creates a bag named 'mybag' where autosave is off and the
# backend is pickle
bag4 = propbag('mybag', autosave = False, backend = backendformat.pickle)
bag4.save()

# creates an encrypted bag
bag5 = propbag(secret_key = 'supersecretpassword')
print(bag5.location)

Adding property items

Use the propbag.add(items) method to add property item(s) to the bag.

Returns a list of all the added property items.

Adding property items is very flexible. It is acceptable to add one or many with one call. It can be just a name, a collection, or a property item instance. Adding by list can be name/value pairs or a collection of property items. Adding by dictionary uses the key for the name and the value for the property item’s value.

from propdb.propbag import propbag

# create new bag
bag = propbag('mybag')

# adds a property item with the value set to None
bag.add('item1')

# by list of name/value pairs
bag.add(('item1', 1, 'item2', 2, ...))

# by dictionary
bag.add({'item1':1, 'item2':2, ...})

# by list or propitems
bag.add((propitem, propitem, ...))

# by propitem
bag.add(propitem)

Adding property items with the + and += operators can be done in the same exact way as the add method (e.g. propbag + propitem, etc). The only difference is that there is no return value when adding by operator.

For example:

bag + 'item1'
bag += ('item1', 1, 'item2', 2, ...)

Updating property items

Use propbag.set to update property item(s) in the bag.

Returns a list of all the updated property items.

Updating property items is very flexible. It is acceptable to update one or many with one call. It can be a collection or an instance of a property item. Updating by list must be by name/value pairs or a collection of property items. Updating by dictionary assumes the key to be the name and the dictionary value the value of the property item.

from propdb.propbag import propbag

# create new bag
bag = propbag('mybag')

# by list of name/value pairs
bag.set(('item1', 1, 'item2', 2, ...))

# by dictionary
bag.set({'item1':1, 'item2':2, ...})

# by list or propitems
bag.set((propitem, propitem, ...))

# by propitem
bag.set(propitem)

Updating property items with the [] operator can be done by indexing the property bag with the name of the property item and passing in a new value or a property item.

For example:

bag['item1'] = value
bag[propitem.name] = propitem

Deleting property items

Use propbag.drop to delete property item(s) from the bag.

Returns the number of property items dropped.

Dropping property items is very flexible. It is acceptable to drop one or many with one call. It can be a single string, property item, or list.

Delete one property item by passing the name of the item to delete. Passing a list can either be a list of names or property items, mixed is acceptable as well (e.g. (‘item1’, propitem)).

from propdb.propbag import propbag

# create new bag
bag = propbag('mybag')

# drops one property by name
bag.drop('item1')

# drops one property item by name
bag.drop(propitem)

# by list of names
bag.drop(('item1', 'item2', 'item3', ...))

# by list of propitems
bag.drop((propitem, propitem, ...))

Dropping property items with the - and -= operators can be done in the same exact way as the drop method (e.g. propbag - propitem, etc). The only difference is that there is no return value when dropping by operator.

For example:

bag - 'item1' # drops one property item by name
bag -= ('item1', 'item2', 'item3', ...) # via list of names

Sync’ing property items

Use propbag.sync to sync changes in a bag if altered by a different instance of the same bag.

Setting autosync to true when instantiating a property bag will activate this feature automatically.

from propdb.propbag import propbag

# create two bags that point to the same bag
bag1 = propbag('mybag')
bag2 = propbag('mybag')

# create property item in bag1
bag1.add({'item1':1})

# sync bag2...bag2 now has item1
bag2.sync()

Changes

0.3.0 - Sync and autosync features added to property bags.

0.2.0 - Supports two types of serialization: backendformat.json (default) and backendformat.pickle. Supports saving the bag encrypted with M2Crypto.

0.1.4 - Added unittests and fixed a bug when adding by dictionary

<= 0.1.3 - Working out the details of publishing to PyPI

 
File Type Py Version Uploaded on Size
propdb-0.3.0.zip (md5) Source 2014-04-28 21KB
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