###################
VirtualDownloadView
###################

.. py:module:: django_downloadview.views.virtual

:class:`VirtualDownloadView` **serves files that do not live on disk**.
Use it when you want to stream a file which content is dynamically generated
or which lives in memory.

It is all about overriding :meth:`VirtualDownloadView.get_file` method so that
it returns a suitable file wrapper...

.. note::

   Current implementation does not support reverse-proxy optimizations,
   because content is actually generated within Django, not stored in some
   third-party place.


************
Base options
************

:class:`VirtualDownloadView` inherits from
:class:`~django_downloadview.views.base.DownloadMixin`, which has various
options such as :attr:`~django_downloadview.views.base.DownloadMixin.basename`
or :attr:`~django_downloadview.views.base.DownloadMixin.attachment`.


***************************************
Serve text (string or unicode) or bytes
***************************************

Let's consider you build text dynamically, as a bytes or string or unicode
object. Serve it with Django's builtin
:class:`~django.core.files.base.ContentFile` wrapper:

.. literalinclude:: /../demo/demoproject/virtual/views.py
   :language: python
   :lines: 3-5, 8-13


**************
Serve StringIO
**************

:class:`~StringIO.StringIO` object lives in memory. Let's wrap it in some
download view via :class:`~django_downloadview.files.VirtualFile`:

.. literalinclude:: /../demo/demoproject/virtual/views.py
   :language: python
   :lines: 1-2, 5-6, 14-20


************************
Stream generated content
************************

Let's consider you have a generator function (``yield``) or an iterator object
(``__iter__()``):


.. literalinclude:: /../demo/demoproject/virtual/views.py
   :language: python
   :lines: 23-26


Stream generated content using :class:`VirtualDownloadView`,
:class:`~django_downloadview.files.VirtualFile` and
:class:`~django_downloadview.io.BytesIteratorIO`:

.. literalinclude:: /../demo/demoproject/virtual/views.py
   :language: python
   :lines: 5-9, 29-33


*************
API reference
*************

.. autoclass:: VirtualDownloadView
   :members:
   :undoc-members:
   :show-inheritance:
   :member-order: bysource