Fixed #13162 and #11597 -- Improved the file handling documentation: Removed documentation of methods on django.core.files.File that did not exist, added documentation for undocumented methods and attributes that did exist, did a general cleanup of the text and organization, and added more metadata targets. Thanks to amenasse and tyrion.mx for the reports.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@14833 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Gabriel Hurley 2010-12-05 07:35:10 +00:00
parent 0ab50aad36
commit 2dd594dff4
3 changed files with 81 additions and 67 deletions

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@ -1,56 +1,54 @@
The ``File`` object
===================
The :mod:`django.core.files` module and its submodules contain built-in classes
for basic file handling in Django.
.. currentmodule:: django.core.files
``File`` attributes and methods
-------------------------------
The :mod:`django.core.files` module contains a built-in class for basic file
handling in Django. The :class:`File` class has the following attributes and
methods:
The ``File`` Class
------------------
.. class:: File(file_object)
The :class:`File` is a thin wrapper around Python's built-in file object
with some Django-specific additions. Internally, Django uses this class
any time it needs to represent a file.
:class:`File` objects have the following attributes and methods:
.. attribute:: name
The name of file including the relative path from :setting:`MEDIA_ROOT`.
.. attribute:: path
The absolute path to the file's location on a local filesystem.
:doc:`Custom file storage systems </howto/custom-file-storage>` may not store
files locally; files stored on these systems will have a ``path`` of
``None``.
.. attribute:: url
The URL where the file can be retrieved. This is often useful in
:doc:`templates </topics/templates>`; for example, a bit of a template for
displaying a ``Car`` (see above) might look like:
.. code-block:: html+django
<img src='{{ car.photo.url }}' alt='{{ car.name }}' />
The name of file including the relative path from
:setting:`MEDIA_ROOT`.
.. attribute:: size
The size of the file in bytes.
.. attribute:: file
The underlying Python ``file`` object passed to
:class:`~django.core.files.File`.
.. attribute:: mode
The read/write mode for the file.
.. method:: open([mode=None])
Open or reopen the file (which by definition also does ``File.seek(0)``).
The ``mode`` argument allows the same values as Python's standard
``open()``.
Open or reopen the file (which by definition also does
``File.seek(0)``). The ``mode`` argument allows the same values
as Python's standard ``open()``.
When reopening a file, ``mode`` will override whatever mode the file was
originally opened with; ``None`` means to reopen with the original mode.
When reopening a file, ``mode`` will override whatever mode the file
was originally opened with; ``None`` means to reopen with the original
mode.
.. method:: read([num_bytes=None])
Read content from the file. The optional ``size`` is the number of bytes to
read; if not specified, the file will be read to the end.
Read content from the file. The optional ``size`` is the number of
bytes to read; if not specified, the file will be read to the end.
.. method:: __iter__()
@ -61,38 +59,65 @@ methods:
Iterate over the file yielding "chunks" of a given size. ``chunk_size``
defaults to 64 KB.
This is especially useful with very large files since it allows them to be
streamed off disk and avoids storing the whole file in memory.
This is especially useful with very large files since it allows them to
be streamed off disk and avoids storing the whole file in memory.
.. method:: multiple_chunks([chunk_size=None])
Returns ``True`` if the file is large enough to require multiple chunks to
access all of its content give some ``chunk_size``.
Returns ``True`` if the file is large enough to require multiple chunks
to access all of its content give some ``chunk_size``.
.. method:: write([content])
Writes the specified content string to the file. Depending on the storage
system behind the scenes, this content might not be fully committed until
``close()`` is called on the file.
Writes the specified content string to the file. Depending on the
storage system behind the scenes, this content might not be fully
committed until ``close()`` is called on the file.
.. method:: close()
Close the file.
In addition to the listed methods, :class:`~django.core.files.File` exposes
the following attributes and methods of the underlying ``file`` object:
``encoding``, ``fileno``, ``flush``, ``isatty``, ``newlines``,
``read``, ``readinto``, ``readlines``, ``seek``, ``softspace``, ``tell``,
``truncate``, ``writelines``, ``xreadlines``.
.. currentmodule:: django.core.files.base
The ``ContentFile`` Class
-------------------------
.. class:: ContentFile(File)
The ``ContentFile`` class inherits from :class:`~django.core.files.File`,
but unlike :class:`~django.core.files.File` it operates on string content,
rather than an actual file. For example::
from django.core.files.base import ContentFile
f1 = ContentFile("my string content")
f2 = ContentFile(u"my unicode content encoded as UTF-8".encode('UTF-8'))
.. currentmodule:: django.core.files.images
Additional ``ImageFile`` attributes
------------------------------------
The ``ImageFile`` Class
-----------------------
.. class:: ImageFile(file_object)
Django provides a built-in class specifically for images.
:class:`django.core.files.images.ImageFile` inherits all the attributes
and methods of :class:`~django.core.files.File`, and additionally
provides the following:
.. attribute:: width
Width of the image.
Width of the image in pixels.
.. attribute:: height
Height of the image.
Height of the image in pixels.
.. currentmodule:: django.core.files
@ -100,7 +125,7 @@ Additional methods on files attached to objects
-----------------------------------------------
Any :class:`File` that's associated with an object (as with ``Car.photo``,
above) will also have a couple of extra methods:
below) will also have a couple of extra methods:
.. method:: File.save(name, content, [save=True])
@ -116,23 +141,12 @@ above) will also have a couple of extra methods:
>>> car.photo.save('myphoto.jpg', contents, save=True)
Note that the ``content`` argument must be an instance of
:class:`File` or of a subclass of :class:`File` such as :class:`ContentFile`.
Note that the ``content`` argument must be an instance of either
:class:`File` or of a subclass of :class:`File`, such as
:class:`ContentFile`.
.. method:: File.delete([save=True])
Remove the file from the model instance and delete the underlying file. The
``save`` argument works as above.
``ContentFile`` objects
-----------------------
.. class:: ContentFile(File)
A ``ContentFile`` is a File-like object that takes string content, rather
than an actual file::
from django.core.files.base import ContentFile
f1 = ContentFile("my string content")
f2 = ContentFile(u"my unicode content encoded as UTF-8".encode('UTF-8'))
Removes the file from the model instance and deletes the underlying file.
If ``save`` is ``True``, the model's ``save()`` method will be called once
the file is deleted.

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@ -6,7 +6,7 @@ File handling
:synopsis: File handling and storage
.. toctree::
:maxdepth: 1
:maxdepth: 2
file
storage

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@ -50,9 +50,9 @@ it has all the methods and attributes described below.
The ``File`` object
===================
Internally, Django uses a ``django.core.files.File`` any time it needs to
represent a file. This object is a thin wrapper around Python's `built-in file
object`_ with some Django-specific additions.
Internally, Django uses a :class:`django.core.files.File` instance any time it
needs to represent a file. This object is a thin wrapper around Python's
`built-in file object`_ with some Django-specific additions.
.. _built-in file object: http://docs.python.org/library/stdtypes.html#bltin-file-objects
@ -68,8 +68,8 @@ using a Python built-in ``file`` object::
>>> f = open('/tmp/hello.world', 'w')
>>> myfile = File(f)
Now you can use any of the ``File`` attributes and methods documented in
:doc:`/ref/files/file`.
Now you can use any of the documented attributes and methods
of the :class:`~django.core.files.File` class.
File storage
============