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121 lines
3.6 KiB
Text
121 lines
3.6 KiB
Text
.. _ref-files-file:
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The ``File`` object
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===================
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.. currentmodule:: django.core.files
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.. class:: File(file_object)
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``File`` attributes and methods
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-------------------------------
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Django's ``File`` has the following attributes and methods:
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.. attribute:: File.name
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The name of file including the relative path from :setting:`MEDIA_ROOT`.
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.. attribute:: File.path
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The absolute path to the file's location on a local filesystem.
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:ref:`Custom file storage systems <howto-custom-file-storage>` may not store
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files locally; files stored on these systems will have a ``path`` of
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``None``.
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.. attribute:: File.url
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The URL where the file can be retrieved. This is often useful in
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:ref:`templates <topics-templates>`; for example, a bit of a template for
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displaying a ``Car`` (see above) might look like:
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.. code-block:: html+django
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<img src='{{ car.photo.url }}' alt='{{ car.name }}' />
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.. attribute:: File.size
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The size of the file in bytes.
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.. method:: File.open(mode=None)
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Open or reopen the file (which by definition also does ``File.seek(0)``).
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The ``mode`` argument allows the same values as Python's standard
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``open()``.
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When reopening a file, ``mode`` will override whatever mode the file was
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originally opened with; ``None`` means to reopen with the original mode.
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.. method:: File.read(num_bytes=None)
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Read content from the file. The optional ``size`` is the number of bytes to
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read; if not specified, the file will be read to the end.
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.. method:: File.__iter__()
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Iterate over the file yielding one line at a time.
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.. method:: File.chunks(chunk_size=None)
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Iterate over the file yielding "chunks" of a given size. ``chunk_size``
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defaults to 64 KB.
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This is especially useful with very large files since it allows them to be
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streamed off disk and avoids storing the whole file in memory.
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.. method:: File.multiple_chunks(chunk_size=None)
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Returns ``True`` if the file is large enough to require multiple chunks to
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access all of its content give some ``chunk_size``.
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.. method:: File.write(content)
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Writes the specified content string to the file. Depending on the storage
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system behind the scenes, this content might not be fully committed until
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``close()`` is called on the file.
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.. method:: File.close()
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Close the file.
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Additional ``ImageField`` attributes
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------------------------------------
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.. attribute:: File.width
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Width of the image.
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.. attribute:: File.height
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Height of the image.
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Additional methods on files attached to objects
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-----------------------------------------------
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.. highlight:: pycon
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Any :class:`File` that's associated with an object (as with ``Car.photo``,
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above) will also have a couple of extra methods:
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.. method:: File.save(name, content, save=True)
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Saves a new file with the file name and contents provided. This will not
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replace the existing file, but will create a new file and update the object
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to point to it. If ``save`` is ``True``, the model's ``save()`` method will
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be called once the file is saved. That is, these two lines::
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>>> car.photo.save('myphoto.jpg', contents, save=False)
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>>> car.save()
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are the same as this one line::
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>>> car.photo.save('myphoto.jpg', contents, save=True)
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Note that the ``content`` argument must be an instance of
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:class:`File` or of a subclass of :class:`File`.
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.. method:: File.delete(save=True)
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Remove the file from the model instance and delete the underlying file. The
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``save`` argument works as above.
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