django/docs/ref/files/file.txt

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The ``File`` object
===================
.. 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:
.. class:: File(file_object)
.. 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 }}' />
.. attribute:: size
The size of the file in bytes.
.. 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()``.
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.
.. method:: __iter__()
Iterate over the file yielding one line at a time.
.. method:: chunks([chunk_size=None])
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.
.. 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``.
.. 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.
.. method:: close()
Close the file.
.. currentmodule:: django.core.files.images
Additional ``ImageFile`` attributes
------------------------------------
.. class:: ImageFile(file_object)
.. attribute:: width
Width of the image.
.. attribute:: height
Height of the image.
.. currentmodule:: django.core.files
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:
.. method:: File.save(name, content, [save=True])
Saves a new file with the file name and contents provided. This will not
replace the existing file, but will create a new file and update the object
to point to it. If ``save`` is ``True``, the model's ``save()`` method will
be called once the file is saved. That is, these two lines::
>>> car.photo.save('myphoto.jpg', contents, save=False)
>>> car.save()
are the same as this one line::
>>> 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`.
.. 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'))