##################
Make your own view
##################

.. currentmodule:: django_downloadview.views.base


*************
DownloadMixin
*************

The :py:class:`django_downloadview.views.DownloadMixin` class is not a view. It
is a base class which you can inherit of to create custom download views.

``DownloadMixin`` is a base of `BaseDownloadView`_, which itself is a base of
all other django_downloadview's builtin views.

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


****************
BaseDownloadView
****************

The :py:class:`django_downloadview.views.BaseDownloadView` class is a base
class to create download views. It inherits `DownloadMixin`_ and
:py:class:`django.views.generic.base.View`.

The only thing it does is to implement
:py:meth:`get <django_downloadview.views.BaseDownloadView.get>`: it triggers
:py:meth:`DownloadMixin's render_to_response
<django_downloadview.views.DownloadMixin.render_to_response>`.

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


***********************************************
Serving a file inline rather than as attachment
***********************************************

Use :attr:`~DownloadMixin.attachment` to make a view serve a file inline rather
than as attachment, i.e. to display the file as if it was an internal part of a
page rather than triggering "Save file as..." prompt.

See details in :attr:`attachment API documentation
<~DownloadMixin.attachment>`.

.. literalinclude:: /../demo/demoproject/object/views.py
   :language: python
   :lines: 1-5, 20-23


************************************
Handling http not modified responses
************************************

Sometimes, you know the latest date and time the content was generated at, and
you know a new request would generate exactly the same content. In such a case,
you should implement :py:meth:`~VirtualDownloadView.was_modified_since` in your
view.

.. note::

   Default :py:meth:`~VirtualDownloadView.was_modified_since` implementation
   trusts file wrapper's ``was_modified_since`` if any. Else (if calling
   ``was_modified_since()`` raises ``NotImplementedError`` or
   ``AttributeError``) it returns ``True``, i.e. it assumes the file was
   modified.

As an example, the download views above always generate "Hello world!"... so,
if the client already downloaded it, we can safely return some HTTP "304 Not
Modified" response:

.. code:: python

   from django.core.files.base import ContentFile
   from django_downloadview import VirtualDownloadView

   class TextDownloadView(VirtualDownloadView):
       def get_file(self):
           """Return :class:`django.core.files.base.ContentFile` object."""
           return ContentFile(u"Hello world!", name='hello-world.txt')

       def was_modified_since(self, file_instance, since):
           return False  # Never modified, always u"Hello world!".