Django2.0手册:File storage API



Getting the current storage class¶

Django provides two convenient ways to access the current storage class:

class DefaultStorage[source]

DefaultStorage provides
lazy access to the current default storage system as defined by
DEFAULT_FILE_STORAGE. DefaultStorage uses
get_storage_class() internally.

get_storage_class(import_path=None)[source]

Returns a class or module which implements the storage API.

When called without the import_path parameter get_storage_class
will return the current default storage system as defined by
DEFAULT_FILE_STORAGE. If import_path is provided,
get_storage_class will attempt to import the class or module from the
given path and will return it if successful. An exception will be
raised if the import is unsuccessful.

The FileSystemStorage class¶

class FileSystemStorage(location=None, base_url=None, file_permissions_mode=None, directory_permissions_mode=None)[source]

The FileSystemStorage class implements
basic file storage on a local filesystem. It inherits from
Storage and provides implementations
for all the public methods thereof.

location

Absolute path to the directory that will hold the files.
Defaults to the value of your MEDIA_ROOT setting.

base_url

URL that serves the files stored at this location.
Defaults to the value of your MEDIA_URL setting.

file_permissions_mode

The file system permissions that the file will receive when it is
saved. Defaults to FILE_UPLOAD_PERMISSIONS.

directory_permissions_mode

The file system permissions that the directory will receive when it is
saved. Defaults to FILE_UPLOAD_DIRECTORY_PERMISSIONS.

Note

The FileSystemStorage.delete() method will not raise
an exception if the given file name does not exist.

get_created_time(name)[source]

Returns a datetime of the system’s ctime, i.e.
os.path.getctime(). On some systems (like Unix), this is the
time of the last metadata change, and on others (like Windows), it’s
the creation time of the file.

The Storage class¶

class Storage[source]

The Storage class provides a
standardized API for storing files, along with a set of default
behaviors that all other storage systems can inherit or override
as necessary.

Note

When methods return naive datetime objects, the effective timezone
used will be the current value of os.environ['TZ']; note that this
is usually set from Django’s TIME_ZONE.

delete(name)[source]

Deletes the file referenced by name. If deletion is not supported
on the target storage system this will raise NotImplementedError
instead

exists(name)[source]

Returns True if a file referenced by the given name already exists
in the storage system, or False if the name is available for a new
file.

get_accessed_time(name)[source]

Returns a datetime of the last accessed time of the
file. For storage systems unable to return the last accessed time this
will raise NotImplementedError.

If USE_TZ is True, returns an aware datetime,
otherwise returns a naive datetime in the local timezone.

get_available_name(name, max_length=None)[source]

Returns a filename based on the name parameter that’s free and
available for new content to be written to on the target storage
system.

The length of the filename will not exceed max_length, if provided.
If a free unique filename cannot be found, a
SuspiciousFileOperation exception will be raised.

If a file with name already exists, an underscore plus a random
7 character alphanumeric string is appended to the filename before
the extension.

get_created_time(name)[source]

Returns a datetime of the creation time of the file.
For storage systems unable to return the creation time this will raise
NotImplementedError.

If USE_TZ is True, returns an aware datetime,
otherwise returns a naive datetime in the local timezone.

get_modified_time(name)[source]

Returns a datetime of the last modified time of the
file. For storage systems unable to return the last modified time this
will raise NotImplementedError.

If USE_TZ is True, returns an aware datetime,
otherwise returns a naive datetime in the local timezone.

get_valid_name(name)[source]

Returns a filename based on the name parameter that’s suitable
for use on the target storage system.

generate_filename(filename)[source]

Validates the filename by calling get_valid_name() and
returns a filename to be passed to the save() method.

The filename argument may include a path as returned by
FileField.upload_to.
In that case, the path won’t be passed to get_valid_name() but
will be prepended back to the resulting name.

The default implementation uses os.path operations. Override
this method if that’s not appropriate for your storage.

listdir(path)[source]

Lists the contents of the specified path, returning a 2-tuple of lists;
the first item being directories, the second item being files. For
storage systems that aren’t able to provide such a listing, this will
raise a NotImplementedError instead.

open(name, mode=’rb’)[source]

Opens the file given by name. Note that although the returned file
is guaranteed to be a File object, it might actually be some
subclass. In the case of remote file storage this means that
reading/writing could be quite slow, so be warned.

path(name)[source]

The local filesystem path where the file can be opened using Python’s
standard open(). For storage systems that aren’t accessible from
the local filesystem, this will raise NotImplementedError instead.

save(name, content, max_length=None)[source]

Saves a new file using the storage system, preferably with the name
specified. If there already exists a file with this name name, the
storage system may modify the filename as necessary to get a unique
name. The actual name of the stored file will be returned.

The max_length argument is passed along to
get_available_name().

The content argument must be an instance of
django.core.files.File or a file-like object that can be
wrapped in File.

size(name)[source]

Returns the total size, in bytes, of the file referenced by name.
For storage systems that aren’t able to return the file size this will
raise NotImplementedError instead.

url(name)[source]

Returns the URL where the contents of the file referenced by name
can be accessed. For storage systems that don’t support access by URL
this will raise NotImplementedError instead.