During file uploads, the actual file data is stored in request.FILES
. Each entry in this dictionary is an
UploadedFile
object (or a subclass) – a wrapper around an uploaded file.
You’ll usually use one of these methods to access the uploaded content:
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.
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.
A generator returning chunks of the file. If multiple_chunks()
is
True
, you should use this method in a loop instead of read()
.
In practice, it’s often easiest to use chunks()
all the time. Looping
over chunks()
instead of using read()
ensures that large files
don’t overwhelm your system’s memory.
Here are some useful attributes of UploadedFile
:
The name of the uploaded file (e.g. my_file.txt
).
The size, in bytes, of the uploaded file.
The content-type header uploaded with the file (e.g. text/plain or 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.”
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).
For text/* content-types, the character set (i.e. utf8
)
supplied by the browser. Again, “trust but verify” is the best policy here.
Note
Like regular Python files, you can read the file line-by-line by iterating over the uploaded file:
for line in uploadedfile:
do_something_with(line)
Lines are split using universal newlines. The following are
recognized as ending a line: the Unix end-of-line convention '\n'
, the
Windows convention '\r\n'
, and the old Macintosh convention '\r'
.
Subclasses of UploadedFile
include:
A file uploaded to a temporary location (i.e. stream-to-disk). This class
is used by the
TemporaryFileUploadHandler
. In
addition to the methods from UploadedFile
, it has one additional
method:
Returns the full path to the temporary uploaded file.
A file uploaded into memory (i.e. stream-to-memory). This class is used
by the MemoryFileUploadHandler
.
Together the MemoryFileUploadHandler
and
TemporaryFileUploadHandler
provide Django’s default file upload
behavior of reading small files into memory and large ones onto disk. They
are located in django.core.files.uploadhandler
.
File upload handler to stream uploads into memory (used for small files).
Upload handler that streams data into a temporary file using
TemporaryUploadedFile
.
All file upload handlers should be subclasses of
django.core.files.uploadhandler.FileUploadHandler
. You can define upload
handlers wherever you wish.
Custom file upload handlers must define the following methods:
Receives a “chunk” of data from the file upload.
raw_data
is a bytestring 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.
Custom upload handlers may also define any of the following optional methods or attributes:
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 (231 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*210 bytes, or 64 KB.
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 filename 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 UploadedFile.content_type_extra
.
This method may raise a StopFutureHandlers
exception to prevent
future handlers from handling this file.
Callback signaling that the entire upload (all files) has completed.
Callback signaling that the upload was interrupted, e.g. when the user closed their browser during file upload.
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.
Nov 05, 2024