django1/docs/ref/files/file.txt

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.. _ref-files-file:
The ``File`` object
===================
.. currentmodule:: django.core.files
.. class:: File(file_object)
``File`` attributes and methods
-------------------------------
Django's ``File`` has the following attributes and methods:
``File.path``
~~~~~~~~~~~~~
The absolute path to the file's location on a local filesystem.
:ref:`Custom file storage systems <howto-custom-file-storage>` may not store
files locally; files stored on these systems will have a ``path`` of ``None``.
``File.url``
~~~~~~~~~~~~
The URL where the file can be retrieved. This is often useful in :ref:`templates
<topics-templates>`; for example, a bit of a template for displaying a ``Car``
(see above) might look like::
<img src='{{ car.photo.url }}' alt='{{ car.name }}' />
``File.size``
~~~~~~~~~~~~~
The size of the file in bytes.
``File.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.
``File.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.
``File.__iter__()``
~~~~~~~~~~~~~~~~~~~
Iterate over the file yielding one line at a time.
``File.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.
``File.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``.
``File.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.
``File.close()``
~~~~~~~~~~~~~~~~
Close the file.
Additional ``ImageField`` attributes
------------------------------------
``File.width`` and ``File.height``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
These attributes provide the dimensions of the image.
Additional methods on files attached to objects
-----------------------------------------------
Any ``File`` that's associated with an object (as with ``Car.photo``, above)
will also have a couple of extra methods:
``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)
``File.delete(save=True)``
~~~~~~~~~~~~~~~~~~~~~~~~~~
Remove the file from the model instance and delete the underlying file. The
``save`` argument works as above.