154 lines
4.8 KiB
Plaintext
154 lines
4.8 KiB
Plaintext
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
|
|
|
|
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:: 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()``.
|
|
|
|
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.
|
|
|
|
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 __future__ import unicode_literals
|
|
from django.core.files.base import ContentFile
|
|
|
|
f1 = ContentFile(b"my string content")
|
|
f2 = ContentFile("my unicode content encoded as UTF-8".encode('UTF-8'))
|
|
|
|
.. currentmodule:: django.core.files.images
|
|
|
|
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 in pixels.
|
|
|
|
.. attribute:: height
|
|
|
|
Height of the image in pixels.
|
|
|
|
.. currentmodule:: django.core.files
|
|
|
|
Additional methods on files attached to objects
|
|
-----------------------------------------------
|
|
|
|
Any :class:`File` that's associated with an object (as with ``Car.photo``,
|
|
below) 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', content, save=False)
|
|
>>> car.save()
|
|
|
|
are the same as this one line::
|
|
|
|
>>> car.photo.save('myphoto.jpg', content, save=True)
|
|
|
|
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])
|
|
|
|
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.
|