sqlalchemy-media

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Documentation

See the documentation_ for full description.

Why ?

Nowadays, most of the database applications are used to allow users to upload and attach files of various types to ORM models.

Handling those jobs is not simple if you have to care about Security, High-Availability, Scalability, CDN and more things you may have already been concerned. Accepting a file from public space, analysing, validating, processing(Normalizing) and making it available to public space again is the main goal of this project.

Sql-Alchemy is the best platform for implementing this stuff. It has the SqlAlchemyMutable_ types facility to manipulate the objects with any type in-place. why not ?

.. note:: The main idea comes from dahlia's SQLAlchemyImageAttach_.

Overview

• Storing and locating any file, tracking it by sqlalchemy models.
• Storage layer is completely separated from data model, with a simple api: (put, delete, open, locate)
• Using any SqlAlchemy data type which interfaces Python dictionary. This is achieved by using the SqlAlchemyTypeDecorators_ and SqlAlchemyMutable_.
• Offering delete_orphan flag to automatically delete files which orphaned via attribute set or delete from collections, or objects leaved in memory alone! by setting it's last pointer to None.
• Attaching files from Url, LocalFileSystem and Streams.
• Extracting the file's mimetype from the backend stream if possible, using magic module.
• Limiting file size(min, max), to prevent DOS attacks.
• Adding timestamp in url to help caching.
• Auto generating thumbnails, using width, height and or ratio.
• Analyzing files & images using magic and wand.
• Validating mimetype, width, height and image ratio.
• Automatically resize & reformat images before store.
• Thanks @YukSeungChan <https://github.com/YukSeungChan>_, for implementing the S3Store and OS2Store.
• SSH/SFTP Store

Quick Start

Here is a simple example to see how to use this library:

.. code-block:: python

import functools import json from os.path import exists, join

from sqlalchemy import create_engine, TypeDecorator, Unicode, Column, Integer from sqlalchemy.orm import sessionmaker from sqlalchemy.ext.declarative import declarative_base

from sqlalchemy_media import StoreManager, FileSystemStore, Image, ImageAnalyzer, ImageValidator, ImageProcessor

TEMP_PATH = '/tmp/sqlalchemy-media' Base = declarative_base() engine = create_engine('sqlite:///:memory:', echo=False) session_factory = sessionmaker(bind=engine)

StoreManager.register( 'fs', functools.partial(FileSystemStore, TEMP_PATH, 'http://static.example.org/'), default=True )

class Json(TypeDecorator): impl = Unicode

  def process_bind_param(self, value, engine):
      return json.dumps(value)

  def process_result_value(self, value, engine):
      if value is None:
          return None

      return json.loads(value)

class ProfileImage(Image): pre_processors = [ ImageAnalyzer(), ImageValidator( minimum=(80, 80), maximum=(800, 600), min_aspect_ratio=1.2, content_types=['image/jpeg', 'image/png'] ), ImageProcessor( fmt='jpeg', width=120, crop=dict( left='10%', top='10%', width='80%', height='80%', ) ) ]

class Person(Base): tablename = 'person'

  id = Column(Integer, primary_key=True)
  name = Column(Unicode(100))
  image = Column(ProfileImage.as_mutable(Json))

  def __repr__(self):
      return "<%s id=%s>" % (self.name, self.id)

Base.metadata.create_all(engine, checkfirst=True)

if name == 'main': session = session_factory()

  with StoreManager(session):
      person1 = Person()
      person1.image = ProfileImage.create_from('https://www.python.org/static/img/[email protected]')
      session.add(person1)
      session.commit()

      print('Content type:', person1.image.content_type)
      print('Extension:', person1.image.extension)
      print('Length:', person1.image.length)
      print('Original filename:', person1.image.original_filename)

      thumbnail = person1.image.get_thumbnail(width=32, auto_generate=True)
      print(thumbnail.height)
      assert exists(join(TEMP_PATH, thumbnail.path))

      thumbnail = person1.image.get_thumbnail(ratio=.3, auto_generate=True)
      print(thumbnail.width, thumbnail.height)
      assert exists(join(TEMP_PATH, thumbnail.path))

      person1.image.attach('https://www.python.org/static/img/python-logo.png')
      session.commit()

      print('Content type:', person1.image.content_type)
      print('Extension:', person1.image.extension)
      print('Length:', person1.image.length)
      print('Original filename:', person1.image.original_filename)

  with StoreManager(session, delete_orphan=True):
      deleted_filename = join(TEMP_PATH, person1.image.path)
      person1.image = None
      session.commit()

      assert not exists(deleted_filename)

      person1.image = ProfileImage.create_from('https://www.python.org/static/img/python-logo.png')
      session.commit()

      print('Content type:', person1.image.content_type)
      print('Extension:', person1.image.extension)
      print('Length:', person1.image.length)
      print('Original filename:', person1.image.original_filename)

Will produce::

Content type: image/jpeg
Extension: .jpg
Length: 2020
Original filename: https://www.python.org/static/img/[email protected]
8
28 7
Content type: image/jpeg
Extension: .jpg
Length: 2080
Original filename: https://www.python.org/static/img/python-logo.png
Content type: image/jpeg
Extension: .jpg
Length: 2080
Original filename: https://www.python.org/static/img/python-logo.png

Examples

Checkout the examples directory in the root of the repo.

Branching

A new branching model is applied to this repository, which consists of a master branch and release branches.

Contribution

• Remember the zen of Python(import this) before doing anything.
• Maximum line width is: 79.

.. _SqlAlchemyMutable: http://docs.sqlalchemy.org/en/latest/orm/extensions/mutable.html .. _SqlAlchemyTypeDecorators: http://docs.sqlalchemy.org/en/latest/core/custom_types.html#typedecorator-recipes .. _SQLAlchemyImageAttach: https://github.com/dahlia/sqlalchemy-imageattach .. _documentation: http://sqlalchemy-media.dobisel.com