Fixed #9535 -- Added a reference guide for file upload classes.

1 files changed, 67 insertions, 282 deletions

diff --git a/docs/topics/http/file-uploads.txt b/docs/topics/http/file-uploads.txt
index 3d4b1a9bdd..7e00af957c 100644
--- a/docs/topics/http/file-uploads.txt
+++ b/docs/topics/http/file-uploads.txt
@@ -64,57 +64,88 @@ something like::
 Notice that we have to pass :attr:`request.FILES <django.http.HttpRequest.FILES>`
 into the form's constructor; this is how file data gets bound into a form.
 
-Handling uploaded files
------------------------
+Here's a common way you might handle an uploaded file::
 
-.. class:: UploadedFile
+    def handle_uploaded_file(f):
+        with open('some/file/name.txt', 'wb+') as destination:
+            for chunk in f.chunks():
+                destination.write(chunk)
 
-    The final piece of the puzzle is handling the actual file data from
-    :attr:`request.FILES <django.http.HttpRequest.FILES>`. Each entry in this
-    dictionary is an ``UploadedFile`` object -- a simple wrapper around an uploaded
-    file. You'll usually use one of these methods to access the uploaded content:
+Looping over ``UploadedFile.chunks()`` instead of using ``read()`` ensures that
+large files don't overwhelm your system's memory.
 
-    .. method:: read()
+There are a few other methods and attributes available on ``UploadedFile``
+objects; see :class:`UploadedFile` for a complete reference.
 
-        Read the entire uploaded data from the file. Be careful with this
-        method: if the uploaded file is huge it can overwhelm your system if you
-        try to read it into memory. You'll probably want to use ``chunks()``
-        instead; see below.
+Handling uploaded files with a model
+------------------------------------
 
-    .. method:: multiple_chunks()
+If you're saving a file on a :class:`~django.db.models.Model` with a
+:class:`~django.db.models.FileField`, using a :class:`~django.forms.ModelForm`
+makes this process much easier. The file object will be saved to the location
+specified by the :attr:`~django.db.models.FileField.upload_to` argument of the
+corresponding :class:`~django.db.models.FileField` when calling
+``form.save()``::
 
-        Returns ``True`` if the uploaded file is big enough to require
-        reading in multiple chunks. By default this will be any file
-        larger than 2.5 megabytes, but that's configurable; see below.
+    from django.http import HttpResponseRedirect
+    from django.shortcuts import render
+    from .forms import ModelFormWithFileField
 
-    .. method:: chunks()
+    def upload_file(request):
+        if request.method == 'POST':
+            form = ModelFormWithFileField(request.POST, request.FILES)
+            if form.is_valid():
+                # file is saved
+                form.save()
+                return HttpResponseRedirect('/success/url/')
+        else:
+            form = ModelFormWithFileField()
+        return render(request, 'upload.html', {'form': form})
 
-        A generator returning chunks of the file. If ``multiple_chunks()`` is
-        ``True``, you should use this method in a loop instead of ``read()``.
+If you are constructing an object manually, you can simply assign the file
+object from :attr:`request.FILES <django.http.HttpRequest.FILES>` to the file
+field in the model::
 
-        In practice, it's often easiest simply to use ``chunks()`` all the time;
-        see the example below.
+    from django.http import HttpResponseRedirect
+    from django.shortcuts import render
+    from .forms import UploadFileForm
+    from .models import ModelWithFileField
 
-    .. attribute:: name
+    def upload_file(request):
+        if request.method == 'POST':
+            form = UploadFileForm(request.POST, request.FILES)
+            if form.is_valid():
+                instance = ModelWithFileField(file_field=request.FILES['file'])
+                instance.save()
+                return HttpResponseRedirect('/success/url/')
+        else:
+            form = UploadFileForm()
+        return render(request, 'upload.html', {'form': form})
 
-        The name of the uploaded file (e.g. ``my_file.txt``).
+Upload Handlers
+===============
 
-    .. attribute:: size
+.. currentmodule:: django.core.files.uploadhandler
 
-        The size, in bytes, of the uploaded file.
+When a user uploads a file, Django passes off the file data to an *upload
+handler* -- a small class that handles file data as it gets uploaded. Upload
+handlers are initially defined in the :setting:`FILE_UPLOAD_HANDLERS` setting,
+which defaults to::
 
-There are a few other methods and attributes available on ``UploadedFile``
-objects; see `UploadedFile objects`_ for a complete reference.
+    ("django.core.files.uploadhandler.MemoryFileUploadHandler",
+     "django.core.files.uploadhandler.TemporaryFileUploadHandler",)
 
-Putting it all together, here's a common way you might handle an uploaded file::
+Together :class:`MemoryFileUploadHandler` and
+:class:`TemporaryFileUploadHandler` provide Django's default file upload
+behavior of reading small files into memory and large ones onto disk.
 
-    def handle_uploaded_file(f):
-        with open('some/file/name.txt', 'wb+') as destination:
-            for chunk in f.chunks():
-                destination.write(chunk)
+You can write custom handlers that customize how Django handles files. You
+could, for example, use custom handlers to enforce user-level quotas, compress
+data on the fly, render progress bars, and even send data to another storage
+location directly without storing it locally. See :ref:`custom_upload_handlers`
+for details on how you can customize or completely replace upload behavior.
 
-Looping over ``UploadedFile.chunks()`` instead of using ``read()`` ensures that
-large files don't overwhelm your system's memory.
+.. _modifying_upload_handlers_on_the_fly:
 
 Where uploaded data is stored
 -----------------------------
@@ -132,8 +163,7 @@ like ``/tmp/tmpzfp6I6.upload``. If an upload is large enough, you can watch this
 file grow in size as Django streams the data onto disk.
 
 These specifics -- 2.5 megabytes; ``/tmp``; etc. -- are simply "reasonable
-defaults". Read on for details on how you can customize or completely replace
-upload behavior.
+defaults" which can be customized as described in the next section.
 
 Changing upload handler behavior
 --------------------------------
@@ -184,134 +214,7 @@ There are a few settings which control Django's file upload behavior:
 :setting:`FILE_UPLOAD_HANDLERS`
     The actual handlers for uploaded files. Changing this setting allows
     complete customization -- even replacement -- of Django's upload
-    process. See `upload handlers`_, below, for details.
-
-    Defaults to::
-
-        ("django.core.files.uploadhandler.MemoryFileUploadHandler",
-         "django.core.files.uploadhandler.TemporaryFileUploadHandler",)
-
-    Which means "try to upload to memory first, then fall back to temporary
-    files."
-
-Handling uploaded files with a model
-------------------------------------
-
-If you're saving a file on a :class:`~django.db.models.Model` with a
-:class:`~django.db.models.FileField`, using a :class:`~django.forms.ModelForm`
-makes this process much easier. The file object will be saved to the location
-specified by the :attr:`~django.db.models.FileField.upload_to` argument of the
-corresponding :class:`~django.db.models.FileField` when calling
-``form.save()``::
-
-    from django.http import HttpResponseRedirect
-    from django.shortcuts import render
-    from .forms import ModelFormWithFileField
-
-    def upload_file(request):
-        if request.method == 'POST':
-            form = ModelFormWithFileField(request.POST, request.FILES)
-            if form.is_valid():
-                # file is saved
-                form.save()
-                return HttpResponseRedirect('/success/url/')
-        else:
-            form = ModelFormWithFileField()
-        return render(request, 'upload.html', {'form': form})
-
-If you are constructing an object manually, you can simply assign the file
-object from :attr:`request.FILES <django.http.HttpRequest.FILES>` to the file
-field in the model::
-
-    from django.http import HttpResponseRedirect
-    from django.shortcuts import render
-    from .forms import UploadFileForm
-    from .models import ModelWithFileField
-
-    def upload_file(request):
-        if request.method == 'POST':
-            form = UploadFileForm(request.POST, request.FILES)
-            if form.is_valid():
-                instance = ModelWithFileField(file_field=request.FILES['file'])
-                instance.save()
-                return HttpResponseRedirect('/success/url/')
-        else:
-            form = UploadFileForm()
-        return render(request, 'upload.html', {'form': form})
-
-
-``UploadedFile`` objects
-========================
-
-In addition to those inherited from :class:`~django.core.files.File`, all
-``UploadedFile`` objects define the following methods/attributes:
-
-.. attribute:: UploadedFile.content_type
-
-    The content-type header uploaded with the file (e.g. :mimetype:`text/plain`
-    or :mimetype:`application/pdf`). Like any data supplied by the user, you
-    shouldn't trust that the uploaded file is actually this type. You'll still
-    need to validate that the file contains the content that the content-type
-    header claims -- "trust but verify."
-
-.. attribute:: UploadedFile.content_type_extra
-
-    .. versionadded:: 1.7
-
-    A dictionary containing extra parameters passed to the ``content-type``
-    header. This is typically provided by services, such as Google App Engine,
-    that intercept and handle file uploads on your behalf. As a result your
-    handler may not receive the uploaded file content, but instead a URL or
-    other pointer to the file. (see `RFC 2388`_ section 5.3).
-
-    .. _RFC 2388: http://www.ietf.org/rfc/rfc2388.txt
-
-.. attribute:: UploadedFile.charset
-
-    For :mimetype:`text/*` content-types, the character set (i.e. ``utf8``)
-    supplied by the browser. Again, "trust but verify" is the best policy here.
-
-.. attribute:: UploadedFile.temporary_file_path()
-
-    Only files uploaded onto disk will have this method; it returns the full
-    path to the temporary uploaded file.
-
-.. note::
-
-    Like regular Python files, you can read the file line-by-line simply by
-    iterating over the uploaded file:
-
-    .. code-block:: python
-
-        for line in uploadedfile:
-            do_something_with(line)
-
-    However, *unlike* standard Python files, :class:`UploadedFile` only
-    understands ``\n`` (also known as "Unix-style") line endings. If you know
-    that you need to handle uploaded files with different line endings, you'll
-    need to do so in your view.
-
-Upload Handlers
-===============
-
-When a user uploads a file, Django passes off the file data to an *upload
-handler* -- a small class that handles file data as it gets uploaded. Upload
-handlers are initially defined in the :setting:`FILE_UPLOAD_HANDLERS` setting,
-which defaults to::
-
-    ("django.core.files.uploadhandler.MemoryFileUploadHandler",
-     "django.core.files.uploadhandler.TemporaryFileUploadHandler",)
-
-Together the ``MemoryFileUploadHandler`` and ``TemporaryFileUploadHandler``
-provide Django's default file upload behavior of reading small files into memory
-and large ones onto disk.
-
-You can write custom handlers that customize how Django handles files. You
-could, for example, use custom handlers to enforce user-level quotas, compress
-data on the fly, render progress bars, and even send data to another storage
-location directly without storing it locally.
-
-.. _modifying_upload_handlers_on_the_fly:
+    process.
 
 Modifying upload handlers on the fly
 ------------------------------------
@@ -371,121 +274,3 @@ list::
         @csrf_protect
         def _upload_file_view(request):
             ... # Process request
-
-
-Writing custom upload handlers
-------------------------------
-
-.. currentmodule:: django.core.files.uploadhandler
-
-.. class:: FileUploadHandler
-
-All file upload handlers should be subclasses of
-``django.core.files.uploadhandler.FileUploadHandler``. You can define upload
-handlers wherever you wish.
-
-Required methods
-~~~~~~~~~~~~~~~~
-
-Custom file upload handlers **must** define the following methods:
-
-.. method:: FileUploadHandler.receive_data_chunk(raw_data, start)
-
-    Receives a "chunk" of data from the file upload.
-
-    ``raw_data`` is a byte string containing the uploaded data.
-
-    ``start`` is the position in the file where this ``raw_data`` chunk
-    begins.
-
-    The data you return will get fed into the subsequent upload handlers'
-    ``receive_data_chunk`` methods. In this way, one handler can be a
-    "filter" for other handlers.
-
-    Return ``None`` from ``receive_data_chunk`` to short-circuit remaining
-    upload handlers from getting this chunk. This is useful if you're
-    storing the uploaded data yourself and don't want future handlers to
-    store a copy of the data.
-
-    If you raise a ``StopUpload`` or a ``SkipFile`` exception, the upload
-    will abort or the file will be completely skipped.
-
-.. method:: FileUploadHandler.file_complete(file_size)
-
-    Called when a file has finished uploading.
-
-    The handler should return an ``UploadedFile`` object that will be stored
-    in ``request.FILES``. Handlers may also return ``None`` to indicate that
-    the ``UploadedFile`` object should come from subsequent upload handlers.
-
-Optional methods
-~~~~~~~~~~~~~~~~
-
-Custom upload handlers may also define any of the following optional methods or
-attributes:
-
-.. attribute:: FileUploadHandler.chunk_size
-
-    Size, in bytes, of the "chunks" Django should store into memory and feed
-    into the handler. That is, this attribute controls the size of chunks
-    fed into ``FileUploadHandler.receive_data_chunk``.
-
-    For maximum performance the chunk sizes should be divisible by ``4`` and
-    should not exceed 2 GB (2\ :sup:`31` bytes) in size. When there are
-    multiple chunk sizes provided by multiple handlers, Django will use the
-    smallest chunk size defined by any handler.
-
-    The default is 64*2\ :sup:`10` bytes, or 64 KB.
-
-.. method:: FileUploadHandler.new_file(field_name, file_name, content_type, content_length, charset, content_type_extra)
-
-    Callback signaling that a new file upload is starting. This is called
-    before any data has been fed to any upload handlers.
-
-    ``field_name`` is a string name of the file ``<input>`` field.
-
-    ``file_name`` is the unicode filename that was provided by the browser.
-
-    ``content_type`` is the MIME type provided by the browser -- E.g.
-    ``'image/jpeg'``.
-
-    ``content_length`` is the length of the image given by the browser.
-    Sometimes this won't be provided and will be ``None``.
-
-    ``charset`` is the character set (i.e. ``utf8``) given by the browser.
-    Like ``content_length``, this sometimes won't be provided.
-
-    ``content_type_extra`` is extra information about the file from the
-    ``content-type`` header. See :attr:`UploadedFile.content_type_extra
-    <django.core.files.uploadedfile.UploadedFile.content_type_extra>`.
-
-    This method may raise a ``StopFutureHandlers`` exception to prevent
-    future handlers from handling this file.
-
-    .. versionadded:: 1.7
-
-        The ``content_type_extra`` parameter was added.
-
-.. method:: FileUploadHandler.upload_complete()
-
-    Callback signaling that the entire upload (all files) has completed.
-
-.. method:: FileUploadHandler.handle_raw_input(input_data, META, content_length, boundary, encoding)
-
-    Allows the handler to completely override the parsing of the raw
-    HTTP input.
-
-    ``input_data`` is a file-like object that supports ``read()``-ing.
-
-    ``META`` is the same object as ``request.META``.
-
-    ``content_length`` is the length of the data in ``input_data``. Don't
-    read more than ``content_length`` bytes from ``input_data``.
-
-    ``boundary`` is the MIME boundary for this request.
-
-    ``encoding`` is the encoding of the request.
-
-    Return ``None`` if you want upload handling to continue, or a tuple of
-    ``(POST, FILES)`` if you want to return the new data structures suitable
-    for the request directly.