The `Request` class (`cubicweb.web`)

------------------------------------

Overview

````````

A request instance is created when an HTTP request is sent to the web server.

It contains informations such as form parameters, user authenticated, etc.

**Globally, a request represents a user query, either through HTTP or not

(we also talk about RQL queries on the server side for example).**

An instance of `Request` has the following attributes:

* `user`, instance of `cubicweb.common.utils.User` corresponding to the authenticated

  user

* `form`, dictionary containing the values of a web form

* `encoding`, character encoding to use in the response

But also:

* `Session data handling`

  * `session_data()`, returns a dictionary containing all the session data

  * `get_session_data(key, default=None)`, returns a value associated to the given

    key or the value `default` if the key is not defined

  * `set_session_data(key, value)`, assign a value to a key

  * `del_session_data(key)`,  suppress the value associated to a key

*  `Cookies handling`

  * `get_cookie()`, returns a dictionary containing the value of the header

    HTTP 'Cookie'

  * `set_cookie(cookie, key, maxage=300)`, adds a header HTTP `Set-Cookie`,

    with a minimal 5 minutes length of duration by default (`maxage` = None

    returns a *session* cookie which will expire when the user closes the browser

    window)

  * `remove_cookie(cookie, key)`, forces a value to expire

* `URL handling`

  * `url()`, returns the full URL of the HTTP request

  * `base_url()`, returns the root URL of the web application

  * `relative_path()`, returns the relative path of the request

* `And more...`

  * `set_content_type(content_type, filename=None)`, adds the header HTTP

    'Content-Type'

  * `get_header(header)`, returns the value associated to an arbitrary header

    of the HTTP request

  * `set_header(header, value)`, adds an arbitrary header in the response

  * `cursor()` returns a RQL cursor on the session

  * `execute(*args, **kwargs)`, shortcut to ``.cursor().execute()``

  * `property_value(key)`, properties management (`CWProperty`)

  * dictionary `data` to store data to share informations between components

    *while a request is executed*

Please note that this class is abstract and that a concrete implementation

will be provided by the *frontend* web used (in particular *twisted* as of

today). For the views or others that are executed on the server side,

most of the interface of `Request` is defined in the session associated

to the client.

API

```

The elements we gave in overview for above are built in three layers,

from ``cubicweb.req.RequestSessionBase``, ``cubicweb.dbapi.DBAPIRequest`` and

``cubicweb.web.CubicWebRequestBase``.

.. autoclass:: cubicweb.req.RequestSessionBase

   :members:

.. autoclass:: cubicweb.dbapi.DBAPIRequest

   :members:

.. autoclass:: cubicweb.web.request.CubicWebRequestBase

   :members: