vcontext 0.23
Context data structure

Context
=======

``vcontext`` package provides single object ``Context``. Context is
dictionary like datastructure with custom access to items. You can
access your data by dot access. Context does not wrap data in itself,
rather just access them. Context has ``data`` attribute where data is
stored.

Install
-------

vcontext is on `pypi <https://pypi.python.org/pypi/vcontext>`__ so you
can simply:

``pip install vcontext``

``__getitem__`` vs ``__getattribute__``
'''''''''''''''''''''''''''''''''''''''

For ``Context`` I have decided to use ``__getitem__`` approach, since I
wanted to have consistent dot access also to lists/tuples. This would be
impossible using ``__getattr__``.

Item
^^^^

Item is dot-separated path to value. This item is splitted and values
have following rules \* string - access to dictionary item or object
attribute \* integer - access to list item \* first part must be string
(since Context is a dictionary)

Example:
        

.. code:: python

   context = Context({
       'status': 200,
       'message': 'OK',
       'result': [
           {
               'user': {
                   'username': 'phonkee',
                   'name': 'Peter Vrba'
               }
           }
       ]
   })
   assert context['result.0.user.username'] == 'phonkee'
   assert context['status'] == 200

If the data is not found, ``KeyError`` is raised on part of item that
was not found. Context provides ``get`` method where you can specify
default value if value is not found and that will never raise exception.

Build items:
------------

Context would be useless if it only supported get of values. Context has
support also to create/delete values on underlying datas by given
``item``. Lets build a structure from previous example:

.. code:: python

   context = Context()
   context['status'] = 200
   context['message'] = 'OK'
   context['result.0.user.username'] = 'phonkee'
   context['result.0.user.name'] = 'Peter Vrba'

   assert context.data == {
       'status': 200,
       'message': 'OK',
       'result': [
           {
               'user': {
                   'username': 'phonkee',
                   'name': 'Peter Vrba'
               }
           }
       ]
   }

Now we try to delete item

.. code:: python

   del context['result.0']
   assert len(context['result']) == 0

Isn’t that cute little helper?

.keys(item=None):
-----------------

Context also supports ``keys`` method. By calling this method context
traverses recursively object. It has support for dict/list, for custom
object it returns just the object key.

.. code:: python

   context = Context()
   context['hello.world'] = 'yay'
   assert context.keys() == ['hello.world']

api:
----

Context provides following methods:

-  ``.copy()`` - deepcopies data and returns new context
-  ``.dumps(item=None)`` - dump to json, attributes:

   -  item - item to be dumped to json

-  ``.items(**kwargs)`` - list of key value items (tuple key, value),
   \**kwargs passed to ``keys`` method
-  ``.iteritems(**kwargs)`` - generator version of items, \**kwargs
   passed to ``keys`` method
-  ``keys(item=None)`` - returns list of all keys, attributes:

   -  item - item to be dumped to json

Contribute:
-----------

Contributions are welcome, there are still a lot of parts to be
enhanced.

TODO:
-----

-  add support for special list key **append** so we can append to list.
   e.g:

.. code:: python

   context['result.usernames.__append__'] = 'phonkee'

Author
------

Peter Vrba (phonkee)