A bunch of cleanups to file documentation. Along the way some references to the old file methods were removed - thanks, varikin.
Fixes #8642. git-svn-id: http://code.djangoproject.com/svn/django/trunk@8862 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Jacob Kaplan-Moss
parent
c1de41f4d2
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bc768e2b47
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@ -45,21 +45,24 @@ Django database layer.
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How do I use image and file fields?
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-----------------------------------
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Using a ``FileField`` or an ``ImageField`` in a model takes a few steps:
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Using a :class:`~django.db.models.FileField` or an
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:class:`~django.db.models.ImageField` in a model takes a few steps:
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#. In your settings file, define ``MEDIA_ROOT`` as the full path to
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a directory where you'd like Django to store uploaded files. (For
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performance, these files are not stored in the database.) Define
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``MEDIA_URL`` as the base public URL of that directory. Make sure that
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this directory is writable by the Web server's user account.
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#. In your settings file, you'll need to define :setting:`MEDIA_ROOT` as the
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full path to a directory where you'd like Django to store uploaded files.
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(For performance, these files are not stored in the database.) Define
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:setting:`MEDIA_URL` as the base public URL of that directory. Make sure
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that this directory is writable by the Web server's user account.
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#. Add the ``FileField`` or ``ImageField`` to your model, making sure
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to define the ``upload_to`` option to tell Django to which subdirectory
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of ``MEDIA_ROOT`` it should upload files.
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#. Add the :class:`~django.db.models.FileField` or
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:class:`~django.db.models.ImageField` to your model, making sure to
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define the :attr:`~django.db.models.FileField.upload_to` option to tell
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Django to which subdirectory of :setting:`MEDIA_ROOT` it should upload
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files.
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#. All that will be stored in your database is a path to the file
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(relative to ``MEDIA_ROOT``). You'll most likely want to use the
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convenience ``get_<fieldname>_url`` function provided by Django. For
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example, if your ``ImageField`` is called ``mug_shot``, you can get the
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absolute URL to your image in a template with
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``{{ object.get_mug_shot_url }}``.
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(relative to :setting:`MEDIA_ROOT`). You'll most likely want to use the
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convenience :attr:`~django.core.files.File.url` attribute provided by
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Django. For example, if your :class:`~django.db.models.ImageField` is
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called ``mug_shot``, you can get the absolute URL to your image in a
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template with ``{{ object.mug_shot.url }}``.
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@ -12,109 +12,110 @@ The ``File`` object
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Django's ``File`` has the following attributes and methods:
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``File.path``
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~~~~~~~~~~~~~
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.. attribute:: File.name
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The absolute path to the file's location on a local filesystem.
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The name of file including the relative path from :setting:`MEDIA_ROOT`.
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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 ``None``.
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.. attribute:: File.path
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``File.url``
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~~~~~~~~~~~~
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The absolute path to the file's location on a local filesystem.
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The URL where the file can be retrieved. This is often useful in :ref:`templates
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<topics-templates>`; for example, a bit of a template for displaying a ``Car``
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(see above) might look like::
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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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<img src='{{ car.photo.url }}' alt='{{ car.name }}' />
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.. attribute:: File.url
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``File.size``
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~~~~~~~~~~~~~
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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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The size of the file in bytes.
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.. code-block:: html+django
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``File.open(mode=None)``
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~~~~~~~~~~~~~~~~~~~~~~~~
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<img src='{{ car.photo.url }}' alt='{{ car.name }}' />
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Open or reopen the file (which by definition also does ``File.seek(0)``). The
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``mode`` argument allows the same values as Python's standard ``open()``.
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.. attribute:: File.size
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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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The size of the file in bytes.
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``File.read(num_bytes=None)``
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. method:: File.open(mode=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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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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``File.__iter__()``
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~~~~~~~~~~~~~~~~~~~
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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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Iterate over the file yielding one line at a time.
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.. method:: File.read(num_bytes=None)
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``File.chunks(chunk_size=None)``
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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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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Iterate over the file yielding "chunks" of a given size. ``chunk_size`` defaults
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to 64 KB.
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.. method:: File.__iter__()
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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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Iterate over the file yielding one line at a time.
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``File.multiple_chunks(chunk_size=None)``
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. method:: File.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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Iterate over the file yielding "chunks" of a given size. ``chunk_size``
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defaults to 64 KB.
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``File.write(content)``
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~~~~~~~~~~~~~~~~~~~~~~~
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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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Writes the specified content string to the file. Depending on the storage system
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behind the scenes, this content might not be fully committed until ``close()``
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is called on the file.
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.. method:: File.multiple_chunks(chunk_size=None)
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``File.close()``
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~~~~~~~~~~~~~~~~
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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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Close the file.
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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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``File.width`` and ``File.height``
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. attribute:: File.width
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These attributes provide the dimensions of the image.
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Width of the image.
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.. attribute:: File.height
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Heigght of the image.
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Additional methods on files attached to objects
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-----------------------------------------------
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Any ``File`` that's associated with an object (as with ``Car.photo``, above)
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will also have a couple of extra methods:
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.. highlight:: pycon
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``File.save(name, content, save=True)``
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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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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Saves a new file with the file name and contents provided. This will not replace
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the existing file, but will create a new file and update the object to point to
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it. If ``save`` is ``True``, the model's ``save()`` method will be called once
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the file is saved. That is, these two lines::
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.. method:: File.save(name, content, save=True)
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>>> car.photo.save('myphoto.jpg', contents, save=False)
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>>> car.save()
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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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are the same as this one line::
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>>> car.photo.save('myphoto.jpg', contents, save=False)
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>>> car.save()
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>>> car.photo.save('myphoto.jpg', contents, save=True)
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are the same as this one line::
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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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>>> car.photo.save('myphoto.jpg', contents, save=True)
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``File.delete(save=True)``
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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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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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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.. 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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@ -415,20 +415,20 @@ A file-upload field. Has one **required** argument:
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.. attribute:: FileField.upload_to
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A local filesystem path that will be appended to your :setting:`MEDIA_ROOT`
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setting to determine the output of the ``get_<fieldname>_url()`` helper
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function.
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setting to determine the value of the :attr:`~django.core.files.File.url`
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attribute.
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This path may contain `strftime formatting`_, which will be replaced by the
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date/time of the file upload (so that uploaded files don't fill up the given
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directory).
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.. versionadded:: 1.0
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.. versionchanged:: 1.0
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This may also be a callable, such as a function, which will be called to
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obtain the upload path, including the filename. This callable must be
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able to accept two arguments, and return a Unix-style path (with forward
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slashes) to be passed along to the storage system. The two arguments that will
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be passed are:
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obtain the upload path, including the filename. This callable must be able
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to accept two arguments, and return a Unix-style path (with forward slashes)
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to be passed along to the storage system. The two arguments that will be
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passed are:
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====================== ===============================================
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Argument Description
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@ -470,15 +470,15 @@ takes a few steps:
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that this directory is writable by the Web server's user account.
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2. Add the :class:`FileField` or :class:`ImageField` to your model, making
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sure to define the :attr:`~FileField.upload_to` option to tell Django to
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which subdirectory of :setting:`MEDIA_ROOT` it should upload files.
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sure to define the :attr:`~FileField.upload_to` option to tell Django
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to which subdirectory of :setting:`MEDIA_ROOT` it should upload files.
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3. All that will be stored in your database is a path to the file
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(relative to :setting:`MEDIA_ROOT`). You'll most likely want to use the
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convenience ``get_<fieldname>_url`` function provided by Django. For
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example, if your :class:`ImageField` is called ``mug_shot``, you can get
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the absolute URL to your image in a template with ``{{
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object.get_mug_shot_url }}``.
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convenience :attr:`~django.core.files.File.url` function provided by
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Django. For example, if your :class:`ImageField` is called ``mug_shot``,
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you can get the absolute URL to your image in a template with
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``{{ object.mug_shot.url }}``.
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For example, say your :setting:`MEDIA_ROOT` is set to ``'/home/media'``, and
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:attr:`~FileField.upload_to` is set to ``'photos/%Y/%m/%d'``. The ``'%Y/%m/%d'``
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@ -488,8 +488,9 @@ day. If you upload a file on Jan. 15, 2007, it will be saved in the directory
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``/home/media/photos/2007/01/15``.
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If you want to retrieve the upload file's on-disk filename, or a URL that refers
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to that file, or the file's size, you can use the ``File.name``, ``File.url``
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and ``File.size`` attributes; see :ref:`topics-files`.
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to that file, or the file's size, you can use the
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:attr:`~django.core.files.File.name`, :attr:`~django.core.files.File.url`
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and :attr:`~django.core.files.File.size` attributes; see :ref:`topics-files`.
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Note that whenever you deal with uploaded files, you should pay close attention
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to where you're uploading them and what type of files they are, to avoid
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@ -581,7 +582,7 @@ image. Has two extra optional arguments:
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Name of a model field which will be auto-populated with the height of the
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image each time the model instance is saved.
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.. attribute:: ImageField.width_field`
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.. attribute:: ImageField.width_field
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Name of a model field which will be auto-populated with the width of the
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image each time the model instance is saved.
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