Class DatabaseStorage can be used with either FileField or ImageField. It can be used to map filenames to database blobs: so you have to use it with a special additional table created manually. The table should contain:
a pk-column for filenames (I think it's better to use the same type that FileField uses: nvarchar(100))
a blob column (image type for example)
*a size column (bigint type).
You can't just create blob column in the same table, where you defined FileField, since there is no way to find required row in the save() method.
Also size field is required to obtain better perfomance (see size() method).
So you can use it with different FileFields and even with different "upload_to" variables used. Thus it implements a kind of root filesystem, where you can define dirs using "upload_to" with FileField and store any files in these dirs. Beware saving file with the same "virtual path" overwrites old file.
It uses either settings.DB_FILES_URL or constructor param 'base_url' (@see init()) to create urls to files. Base url should be mapped to view that provides access to files (see example in the class doc-string). To store files in the same table, where FileField is defined you have to define your own field and provide extra argument (e.g. pk) to save().
Raw sql is used for all operations. In constractor or in DB_FILES of settings.py () you should specify a dictionary with db_table, fname_column, blob_column, size_column and 'base_url'. For example I just put to the settings.py the following line: DB_FILES = {'db_table': 'FILES', 'fname_column': 'FILE_NAME', 'blob_column': 'BLOB', 'size_column': 'SIZE', 'base_url': 'http://localhost/dbfiles/' }" And use it with ImageField as following: player_photo = models.ImageField(upload_to="player_photos", storage = DatabaseStorage() )
DatabaseStorage class uses your settings.py file to perform custom connection to your database. The reason to use custom connection: http://code.djangoproject.com/ticket/5135 Connection string looks like "cnxn = pyodbc.connect('DRIVER={SQL Server};SERVER=localhost;DATABASE=testdb;UID=me;PWD=pass')"
It's based on pyodbc module, so can be used with any database supported by pyodbc. I've tested it with MS Sql Express 2005.
Note: It returns special path, which should be mapped to special view, which returns requested file:
View and usage Example:
def image_view(request, filename):
import os
from django.http import HttpResponse
from django.conf import settings
from django.utils._os import safe_join
from filestorage import DatabaseStorage
from django.core.exceptions import ObjectDoesNotExist
storage = DatabaseStorage()
try:
image_file = storage.open(filename, 'rb')
file_content = image_file.read()
except:
filename = 'no_image.gif'
path = safe_join(os.path.abspath(settings.MEDIA_ROOT), filename)
if not os.path.exists(path):
raise ObjectDoesNotExist
no_image = open(path, 'rb')
file_content = no_image.read()
response = HttpResponse(file_content, mimetype="image/jpeg")
response['Content-Disposition'] = 'inline; filename=%s'%filename
return response
Warning: If filename exist, blob will be overwritten, to change this remove get_available_name(self, name), so Storage.get_available_name(self, name) will be used to generate new filename.
For more information see docstrings in the code.
Please, drop me a line if you've found a mistake or have a suggestion :)
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# 2009 (c) GameKeeper Gambling Ltd, Ivanov E.
from django.core.files.storage import Storage
from django.core.files import File
from django.conf import settings
import StringIO
import urlparse
import pyodbc
class DatabaseStorage(Storage):
"""Class DatabaseStorage provides storing files in the database.
Class DatabaseStorage can be used with either FileField or ImageField.
It can be used to map filenames to database blobs: so you have to use it
with a special additional table created manually. The table should contain a
pk-column for filenames
(better to use the same type that FileField uses: nvarchar(100)), blob field
(image type for example) and size field (bigint).
You can't just create blob column in the same table, where you defined
FileField, since there is no way to find required row in the save() method.
Also size field is required to obtain better perfomance (see size()
method).
So you can use it with different FileFields and even with different
"upload_to" variables used. Thus it implements a kind of root filesystem,
where you can define dirs using "upload_to" with FileField and store any
files in these dirs.
It uses either settings.DB_FILES_URL or constructor param 'base_url'
(@see __init__()) to create urls to files. Base url should be mapped to view
that provides access to files. To store files in the same table, where
FileField is defined you have to define your own field and provide extra
argument (e.g. pk) to save().
Raw sql is used for all operations. In constractor or in DB_FILES of
settings.py () you should specify a dictionary with db_table, fname_column,
blob_column,
size_column and 'base_url'. For example I just put to the settings.py
the following line:
DB_FILES = {'db_table': 'FILES', 'fname_column': 'FILE_NAME',
'blob_column': 'BLOB', 'size_column': 'SIZE', 'base_url': 'http://localhos
/dbfiles/' }"
And use it with ImageField as following:
player_photo = models.ImageField(upload_to="player_photos", storage =
DatabaseStorage() )
DatabaseStorage class uses your settings.py file to perform custom
connection to your database.
The reason to use custom connection:
http://code.djangoproject.com/ticket/5135
Connection string looks like
"cnxn = pyodbc.connect('DRIVER={SQL Server};SERVER=localhost;DATABASE=testdb
UID=me;PWD=pass')"
It's based on pyodbc module, so can be used with any database supported
by pyodbc.
I've tested it with MS Sql Express 2005.
@note It returns special path, which should be mapped to special view,
which returns requested file:
@code
def image_view(request, filename):
import os
from django.http import HttpResponse
from django.conf import settings
from django.utils._os import safe_join
from filestorage import DatabaseStorage
from django.core.exceptions import ObjectDoesNotExist
storage = DatabaseStorage()
try:
image_file = storage.open(filename, 'rb')
file_content = image_file.read()
except:
filename = 'no_image.gif'
path = safe_join(os.path.abspath(settings.MEDIA_ROOT), filename)
if not os.path.exists(path):
raise ObjectDoesNotExist
no_image = open(path, 'rb')
file_content = no_image.read()
response = HttpResponse(file_content, mimetype="image/jpeg")
response['Content-Disposition'] = 'inline; filename=%s'%filename
return response
@endcode
@note If filename exist, blob will be overwritten, to change this remove
get_available_name(self, name), so Storage.get_available_name(self, name)
will be used to
generate new filename.
"""
def __init__(self, option=settings.DB_FILES):
"""Constructor.
Constructs object using dictionary either specified in contucotr or
in settings.DB_FILES.
@param option dictionary with 'db_table', 'fname_column',
'blob_column', 'size_column', 'base_url' keys.
option['db_table']
Table to work with.
option['fname_column']
Column in the 'db_table' containing filenames (filenames can
contain pathes). Values should be the same as where FileField keeps
filenames.
It is used to map filename to blob_column. In sql it's simply
used in where clause.
option['blob_column']
Blob column (for example 'image' type), created manually in the
'db_table', used to store image.
option['size_column']
Column to store file size. Used for optimization of size()
method (another way is to open file and get size)
option['base_url']
Url prefix used with filenames. Should be mapped to the view,
that returns an image as result.
"""
if not option or not (option.has_key('db_table') and option.has_key('fname_column') and option.has_key('blob_column')
and option.has_key('size_column') and option.has_key('base_url') ):
raise ValueError("You didn't specify required options")
self.db_table = option['db_table']
self.fname_column = option['fname_column']
self.blob_column = option['blob_column']
self.size_column = option['size_column']
self.base_url = option['base_url']
#get database settings
self.DATABASE_ODBC_DRIVER = settings.DATABASE_ODBC_DRIVER
self.DATABASE_NAME = settings.DATABASE_NAME
self.DATABASE_USER = settings.DATABASE_USER
self.DATABASE_PASSWORD = settings.DATABASE_PASSWORD
self.DATABASE_HOST = settings.DATABASE_HOST
self.connection = pyodbc.connect('DRIVER=%s;SERVER=%s;DATABASE=%s;UID=%s;PWD=%s'%(self.DATABASE_ODBC_DRIVER,self.DATABASE_HOST,self.DATABASE_NAME,
self.DATABASE_USER, self.DATABASE_PASSWORD) )
self.cursor = self.connection.cursor()
def _open(self, name, mode='rb'):
"""Open a file from database.
@param name filename or relative path to file based on base_url. path should contain only "/", but not "\". Apache sends pathes with "/".
If there is no such file in the db, returs None
"""
assert mode == 'rb', "You've tried to open binary file without specifying binary mode! You specified: %s"%mode
row = self.cursor.execute("SELECT %s from %s where %s = '%s'"%(self.blob_column,self.db_table,self.fname_column,name) ).fetchone()
if row is None:
return None
inMemFile = StringIO.StringIO(row[0])
inMemFile.name = name
inMemFile.mode = mode
retFile = File(inMemFile)
return retFile
def _save(self, name, content):
"""Save 'content' as file named 'name'.
@note '\' in path will be converted to '/'.
"""
name = name.replace('\\', '/')
binary = pyodbc.Binary(content.read())
size = len(binary)
#todo: check result and do something (exception?) if failed.
if self.exists(name):
self.cursor.execute("UPDATE %s SET %s = ?, %s = ? WHERE %s = '%s'"%(self.db_table,self.blob_column,self.size_column,self.fname_column,name),
(binary, size) )
else:
self.cursor.execute("INSERT INTO %s VALUES(?, ?, ?)"%(self.db_table), (name, binary, size) )
self.connection.commit()
return name
def exists(self, name):
row = self.cursor.execute("SELECT %s from %s where %s = '%s'"%(self.fname_column,self.db_table,self.fname_column,name)).fetchone()
return row is not None
def get_available_name(self, name):
return name
def delete(self, name):
if self.exists(name):
self.cursor.execute("DELETE FROM %s WHERE %s = '%s'"%(self.db_table,self.fname_column,name))
self.connection.commit()
def url(self, name):
if self.base_url is None:
raise ValueError("This file is not accessible via a URL.")
return urlparse.urljoin(self.base_url, name).replace('\\', '/')
def size(self, name):
row = self.cursor.execute("SELECT %s from %s where %s = '%s'"%(self.size_column,self.db_table,self.fname_column,name)).fetchone()
if row is None:
return 0
else:
return int(row[0])
|
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Comments
Hello,
Sure, you're welcome. It would be nice, if you leave copyright in the source as it's now.
#
Hello,
Of course :) Added, thanks!
#
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