Django O/R Mapper
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The document features a presentation by Ian Lewis on Django's Object/Relational Mapper (ORM), discussing its functionalities and providing examples of how to use it with database operations. It includes model definitions for RSS feeds and feed items, along with queries and data retrieval methods. The presentation is delivered in a mix of English and Japanese, and concludes with a thank you message.
![Why an O/R Mapper? >>> import MySQLdb >>> db=MySQLdb. connect (passwd= "moonpie" ,db= "mydb" ) >>> >>> c=db. cursor () >>> max_price=5 >>> c. execute ( """SELECT name, spam, eggs, sausage FROM breakfast ... WHERE price < %s """ , (max_price,)) >>> c. fetchall () ( ( "Spam and Sausage Lover's Plate" , 5L, 1L, 8L ), ( "Not So Much Spam Plate" , 3L, 2L, 0L ), ( "Don't Wany ANY SPAM! Plate" , 0L, 4L, 3L ) ) >>> c.executemany( ... """INSERT INTO breakfast (name, spam, eggs, sausage, price) ... VALUES ( %s , %s , %s , %s , %s )""" , ... [ ... ( "Spam and Sausage Lover's Plate" , 5, 1, 8, 7.95 ), ... ( "Not So Much Spam Plate" , 3, 2, 0, 3.95 ), ... ( "Don't Wany ANY SPAM! Plate" , 0, 4, 3, 5.95 ) ... ] )](https://image.slidesharecdn.com/djangoormapper-1232689241898669-1/85/Django-O-R-Mapper-6-320.jpg)
![Database Sync [email_address] ~/src/dlife/dlife $ python manage.py syncdb Creating table auth_permission Creating table auth_group Creating table auth_user Creating table auth_message Creating table django_content_type Creating table django_session Creating table django_site Creating table django_admin_log Creating table django_comments Creating table django_comment_flags Creating table lifestream Creating table feeds Creating table tags Creating table items ...](https://image.slidesharecdn.com/djangoormapper-1232689241898669-1/85/Django-O-R-Mapper-12-320.jpg)
![Queries import feedparser feeds = Feed.objects. filter (feed_basic_feed=False, feed_fetchable=True) for feed in feeds: d = feedparser. parse (feed.feed_url) for entry in d[ 'entries' ]: ... # filters can be chained items_count = Item.objects. filter ( Q (item_date = date_published) | \ Q (item_permalink = permalink) ). filter ( item_feed = feed ). count () ... jQuery ライクなセレクター構文チェーン](https://image.slidesharecdn.com/djangoormapper-1232689241898669-1/85/Django-O-R-Mapper-14-320.jpg)
Django O/R Mapper
- 2. I'll be giving this presentation in English. このプレゼンを英語でさせて頂きます。
- 4. 自己紹介 名前： イアン・ルイス ( Ian Lewis ) 年齢： 27 歳 国籍：米国 Twitter: IanMLewis （ 80 ％日本語） HP: http://www.ianlewis.org/ 所属 : BeProud 好きな物： 勉強。挑戦。 Python 。
- 5. Ask me questions anytime. いつでも、質問をしても良い
- 6. Why an O/R Mapper? >>> import MySQLdb >>> db=MySQLdb. connect (passwd= "moonpie" ,db= "mydb" ) >>> >>> c=db. cursor () >>> max_price=5 >>> c. execute ( """SELECT name, spam, eggs, sausage FROM breakfast ... WHERE price < %s """ , (max_price,)) >>> c. fetchall () ( ( "Spam and Sausage Lover's Plate" , 5L, 1L, 8L ), ( "Not So Much Spam Plate" , 3L, 2L, 0L ), ( "Don't Wany ANY SPAM! Plate" , 0L, 4L, 3L ) ) >>> c.executemany( ... """INSERT INTO breakfast (name, spam, eggs, sausage, price) ... VALUES ( %s , %s , %s , %s , %s )""" , ... [ ... ( "Spam and Sausage Lover's Plate" , 5, 1, 8, 7.95 ), ... ( "Not So Much Spam Plate" , 3, 2, 0, 3.95 ), ... ( "Don't Wany ANY SPAM! Plate" , 0, 4, 3, 5.95 ) ... ] )
- 8. Models Objects Database
- 9. Ok, Let's make a model さて、モデルを作りましょう
- 10. Models class Feed (models.Model): '''A RSS/Atom feed.''' feed_lifestream = models. ForeignKey (Lifestream) feed_name = models. CharField ( "Feed Name" , max_length=255) feed_url = models. URLField ( "Feed Url" , verify_exists=True, max_length=1000) feed_domain = models. CharField ( "Feed Domain" , max_length=255) feed_fetchable = models. BooleanField ( "Is Feed Fetchable?" , default=True) # Used for feeds that allow users to directly add to the lifestream. feed_basic_feed = models. BooleanField ( "Is Basic Feed?" , default=False) objects = FeedManager () def __unicode__ (self): return self.feed_name class Meta : db_table= "feeds"
- 11. Relationships class Item (models.Model): '''A feed item''' # One to many relationship item_feed = models. ForeignKey ( "Item Feed" , Feed) item_date = models. DateTimeField ( "Publish Date" ) item_title = models. CharField ( "Title" , max_length=255) item_content = models. TextField ( "Item Content" , null=True, blank=True) item_permalink = models. UrlField ( "Permalink" , max_length=1000) # Many to Many relationship item_tags = models. ManyToManyField (Tag, null=True, blank=True, db_table="item_tags") ...
- 12. Database Sync [email_address] ~/src/dlife/dlife $ python manage.py syncdb Creating table auth_permission Creating table auth_group Creating table auth_user Creating table auth_message Creating table django_content_type Creating table django_session Creating table django_site Creating table django_admin_log Creating table django_comments Creating table django_comment_flags Creating table lifestream Creating table feeds Creating table tags Creating table items ...
- 13. How do you get at the data? どうやってデータを取れるんですか？
- 14. Queries import feedparser feeds = Feed.objects. filter (feed_basic_feed=False, feed_fetchable=True) for feed in feeds: d = feedparser. parse (feed.feed_url) for entry in d[ 'entries' ]: ... # filters can be chained items_count = Item.objects. filter ( Q (item_date = date_published) | \ Q (item_permalink = permalink) ). filter ( item_feed = feed ). count () ... jQuery ライクなセレクター構文チェーン
- 15. Queries 2 >>> item = Item.objects. get (id=1) >>> item.item_feed.feed_lifestream.ls_title "Ian's Lifestream" 裏技で全部のオクジェクトを出してくれます。便利 便利
- 16. Saving ... i = Item (item_feed = feed, item_date = date_published, item_title = entry. get ( 'title' ), item_content = content, item_content_type = content_type, item_clean_content = clean_content, item_author = entry. get ( 'author' ), item_permalink = permalink ) i. save () # を呼び出しておしまい INSERT/UPDATE を調整してくれるから簡単にできる。
- 18. Thank you for your listening. ご清聴ありがとうございます。