relationship

I have two tables, say A and B. Both have a primary key id. They have a many-to-many relationship, SEC. SEC = Table('sec', Base.metadata, Column('a_id', Integer, ForeignKey('A.id'), primary_key=True, nullable=False), Column('b_id', Integer, ForeignKey('B.id'), primary_key=True, nullable=False) ) class A(): ... id = Column(Integer, primary_key=True) ... rels = relationship(B, secondary=SEC) class B(): ... id = Column(Integer, primary_key=True) ... Let's consider this piece of code. a = A() b1 = B() b2 = B() a.rels = [b1, b2] ... #some place later b3 = B() a.rels = [b1, b3] # errors sometimes

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I have a many to one relationship between the entities Project and Course because each course can have many projects so many projects could be related to the same course. These are my entities: class Project{ /** * @ORM\Id * @ORM\Column(type="integer") * @ORM\GeneratedValue(strategy="AUTO") */ protected $id; //... other fields ... //----------------------- DATABASE RELATIONSHIP ----------------// //PROJECT-COURSE - M:1 relationship /** * @ORM\ManyToOne(targetEntity="Course", inversedBy="project") * @ORM\JoinColumn(name="course_id",

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I am trying to use the django-countries application with Django for the first time but I am getting this error which has me confused. TypeError at /survey/ Person() takes exactly 1 argument (0 given) I installed django-countries 2.1.2 via pip in a virtual environment for the project. INSTALLED_APPS INSTALLED_APPS = ( 'django.contrib.admin', 'django.contrib.auth', 'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.messages', 'django.contrib.staticfiles', 'polls', 'survey', 'django_countries', ) I am using Django 1.6.4.

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I am trying to model a social network with Neo4J. This requires a user can have multiple relationships with another user. When I try to persist these relationships, only one is stored. For example, this is the test unit I do: @Test public void testFindConnections() { Id id1 = new Id(); id1.setId("first-node"); Id id2 = new Id(); id2.setId("second-node"); idService.save(id2); id1.connectedTo(id2, "first-rel"); id1.connectedTo(id2, "second-rel"); idService.save(id1); for (Id im : idService.findAll()) { System.out.println("-" + im.getId()); if

I have problem with separating tables with relationships in different files. I want the tables below to be in three separate files and to import TableA in third party page, but I can not manage the load order. In most of the time I'm receiving the following error. sqlalchemy.exc. InvalidRequestError: When initializing mapper Mapper|TableA|tablea, expression 'TableB' failed to locate a name ("name 'TableB' is not defined"). If this is a class name, consider adding this relationship() to the class after both dependent classes have been defined. class TableA(Base): __tablename__ = "tablea" id =

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I have two SQLAlchemy models set up as follows: ############## # Post Model # ############## class Post(db.Model): id = db.Column(db.Integer, primary_key = True) title = db.Column(db.String(250)) content = db.Column(db.String(5000)) timestamp = db.Column(db.Integer) author_id = db.Column(db.Integer, db.ForeignKey('user.id')) likes = db.relationship('Like', backref = 'post', lazy = 'dynamic') ############### # Likes Model # ############### class Like(db.Model): id = db.Column(db.Integer, primary_key = True) voter_id = db.Column(db.Integer, db

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: I have a model representing user and I want to create a relationship between users representing that they are friends. My functional model with association table and methods to list all the friends look like this friendship = db . Table ( 'friend' , db . Column ( 'id' , db . Integer , primary_key = True ), db . Column ( 'fk_user_from' , db . Integer , db . ForeignKey ( 'user.id' ), nullable = False ), db . Column ( 'fk_user_to' , db . Integer , db . ForeignKey ( 'user.id' ), nullable = False ) ) class User ( db . Model ): ... ...