Description
-----------
The propbd package is a simple database module. 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; therefore, the property
item values must be able to be seriailized by the json module.

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. 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).

Installation
------------
::

	pip install propdb

Basic Usage
-----------
::

    from propdb import propbag as bag
    from propdb import propbag as item
    
    bag1 = bag('bag1', autosave = True)
    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 import propbag
    from propdb import propitem

Create a new property bag
-------------------------
::

    propbag('name', 'location', autosave = True)

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.
::

    # adds a property item with the value set to None
    propbag.add('item1')
    
    # by list of name/value pairs
    propbag.add(('item1', 1, 'item2', 2, ...))
    
    # by dictionary
    propbag.add({'item1':1, 'item2':2, ...})
    
    # by list or propitems
    propbag.add((propitem, propitem, ...))
            
    # by propitem
    propbag.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:
::

    propbag + 'item1'
    propbag += ('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.
::

    # by list of name/value pairs
    propbag.set(('item1', 1, 'item2', 2, ...))
    
    # by dictionary
    propbag.set({'item1':1, 'item2':2, ...})
    
    # by list or propitems
    propbag.set((propitem, propitem, ...))
            
    # by propitem
    propbag.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:
::

    propbag['item1'] = value
    propbag[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)).
::

    # drops one property by name
    propbag.drop('item1')
    
    # drops one property item by name
    propbag.drop(propitem)
    
    # by list of names
    propbag.drop(('item1', 'item2', 'item3', ...))
    
    # by list of propitems
    propbag.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:
::

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