如何在SQLAlchemy的

Question

定義兩個關係到同一個表

我找遍了整個SQLAlchemy的教程和其他類似的問題，但我似乎努力讓該連接工作：

場景：我有模型代表的pages表。頁面可以由用戶創建並由用戶編輯，但不一定是相同的。我Page模型看起來像這樣（有刪節）：

class Page(Base): 
    __tablename__ = 'pages' 

    id = Column(Integer, primary_key = True) 
    slug = Column(Text) 
    title = Column(Text) 
    direct_link = Column(Text) 
    body = Column(Text) 
    category_id = Column(Integer, ForeignKey('categories.id')) 
    published_on = Column(DateTime) 
    publishing_user_id = Column(Integer, ForeignKey('users.id')) 
    last_edit_on = Column(DateTime) 
    last_edit_user_id = Column(Integer, ForeignKey('users.id')) 

    # Define relationships 
    publish_user = relationship('User', backref = backref('pages', order_by = id), primaryjoin = "Page.publishing_user_id == User.id") 
    edit_user = relationship('User', primaryjoin = "Page.last_edit_user_id == User.id") 
    category = relationship('Category', backref = backref('pages', order_by = id)) 

我的用戶存儲在由User模型所表示的用戶表。正如我所說的，我一直在尋找這個SQLAlchemy文檔，我試圖讓它看起來儘可能類似於他們的例子，但不是沒有用。任何幫助將不勝感激。

Answer 1

嘗試foreign_keys選項：

publish_user = relationship(User, foreign_keys=publishing_user_id, 
            primaryjoin=publishing_user_id == User.id, 
            backref=backref('pages', order_by=id)) 
edit_user = relationship(User, foreign_keys=last_edit_user_id, 
           primaryjoin=last_edit_user_id == User.id) 

Answer 2

我覺得你差不多了它的權利;只能在定義primaryjoin時代替Model名稱使用Table名稱。因此，而不是

# Define relationships 
publish_user = relationship('User', backref = backref('pages', order_by = id), 
    primaryjoin = "Page.publishing_user_id == User.id") 
edit_user = relationship('User', 
    primaryjoin = "Page.last_edit_user_id == User.id") 

使用：

# Define relationships 
publish_user = relationship('User', backref = backref('pages', order_by = id), 
    primaryjoin = "pages.publishing_user_id == users.id") 
edit_user = relationship('User', 
    primaryjoin = "pages.last_edit_user_id == users.id") 

Answer 3

隨着0.8版本，可以SQLAlchemy的解決聯接僅使用foreign_keys關鍵字參數的曖昧relationship。

publish_user = relationship(User, foreign_keys=[publishing_user_id], 
            backref=backref('pages', order_by=id)) 
edit_user = relationship(User, foreign_keys=[last_edit_user_id]) 

在http://docs.sqlalchemy.org/en/rel_0_9/orm/join_conditions.html#handling-multiple-join-paths