mirror of
https://github.com/django/django.git
synced 2024-12-23 17:46:27 +00:00
156 lines
5.1 KiB
Plaintext
156 lines
5.1 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, name=None)
|
|
|
|
The :class:`File` class is a thin wrapper around a Python
|
|
:py:term:`file object` with some Django-specific additions.
|
|
Internally, Django uses this class when it needs to represent a file.
|
|
|
|
:class:`File` objects have the following attributes and methods:
|
|
|
|
.. attribute:: name
|
|
|
|
The name of the file including the relative path from
|
|
:setting:`MEDIA_ROOT`.
|
|
|
|
.. attribute:: size
|
|
|
|
The size of the file in bytes.
|
|
|
|
.. attribute:: file
|
|
|
|
The underlying :py:term:`file object` that this class wraps.
|
|
|
|
.. admonition:: Be careful with this attribute in subclasses.
|
|
|
|
Some subclasses of :class:`File`, including
|
|
:class:`~django.core.files.base.ContentFile` and
|
|
:class:`~django.db.models.fields.files.FieldFile`, may replace this
|
|
attribute with an object other than a Python :py:term:`file object`.
|
|
In these cases, this attribute may itself be a :class:`File`
|
|
subclass (and not necessarily the same subclass). Whenever
|
|
possible, use the attributes and methods of the subclass itself
|
|
rather than the those of the subclass's ``file`` attribute.
|
|
|
|
.. attribute:: mode
|
|
|
|
The read/write mode for the file.
|
|
|
|
.. method:: open(mode=None)
|
|
|
|
Open or reopen the file (which also does ``File.seek(0)``).
|
|
The ``mode`` argument allows the same values
|
|
as Python's built-in :func:`python:open()`.
|
|
|
|
When reopening a file, ``mode`` will override whatever mode the file
|
|
was originally opened with; ``None`` means to reopen with the original
|
|
mode.
|
|
|
|
It can be used as a context manager, e.g. ``with file.open() as f:``.
|
|
|
|
.. 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:: close()
|
|
|
|
Close the file.
|
|
|
|
In addition to the listed methods, :class:`~django.core.files.File` exposes
|
|
the following attributes and methods of its ``file`` object:
|
|
``encoding``, ``fileno``, ``flush``, ``isatty``, ``newlines``, ``read``,
|
|
``readinto``, ``readline``, ``readlines``, ``seek``, ``tell``,
|
|
``truncate``, ``write``, ``writelines``, ``readable()``, ``writable()``,
|
|
and ``seekable()``.
|
|
|
|
.. currentmodule:: django.core.files.base
|
|
|
|
The ``ContentFile`` class
|
|
=========================
|
|
|
|
.. class:: ContentFile(content, name=None)
|
|
|
|
The ``ContentFile`` class inherits from :class:`~django.core.files.File`,
|
|
but unlike :class:`~django.core.files.File` it operates on string content
|
|
(bytes also supported), rather than an actual file. For example::
|
|
|
|
from django.core.files.base import ContentFile
|
|
|
|
f1 = ContentFile("esta frase está en español")
|
|
f2 = ContentFile(b"these are bytes")
|
|
|
|
.. currentmodule:: django.core.files.images
|
|
|
|
The ``ImageFile`` class
|
|
=======================
|
|
|
|
.. class:: ImageFile(file_object, name=None)
|
|
|
|
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 is 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 equivalent to::
|
|
|
|
>>> 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:`~django.core.files.base.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.
|