relationship

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 am building a core data iphone app, and having trouble with retrieving one-many relationship data. Please bear with me while I explain. I have used the data model designer to setup an entity called "Item" that contains many entities called "Comment". I then retrieve multiple entities and display them in a UITableView . I fetch these entities like this (in the viewDidLoad method): NSFetchRequest * request = [[ NSFetchRequest alloc ] init ]; NSEntityDescription * entity = [ NSEntityDescription entityForName :@ "Items"

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 these tables tables: class Thing(Base): __tablename__ = 'thing' id = Column(Integer, primary_key=True) class User(Base): __tablename__ = 'user' id = Column(Integer, primary_key=True) class Voteinfo(Base): __tablename__ = 'voteinfo' thing_id = Column(Integer, ForeignKey('thing.id'), primary_key=True) thing = relationship('Thing', backref='voteinfo') upvotes = Column(Integer) downvotes = Column(Integer) def __init__(self, thing) self.thing = thing class VoteThing(Base): __tablename__ = 'votething' id = Column(Integer, primary_key=True)

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 the following data-model in Entity Framework 6.1.3: using System.Data.Entity; public class Student { public int Id { get; set; } public virtual Contact Contact { get; set; } } public class Contact { public int Id { get; set; } public virtual Student Student { get; set; } } public class MyContext : DbContext { protected override void OnModelCreating(DbModelBuilder builder) { builder.Entity<Contact>() .HasOptional(x => x.Student) .WithOptionalDependent(x => x.Contact) .WillCascadeOnDelete(true); } } public static class Program { private

I have a three-levels Invoice model which I'd like to display on Django's admin area... in a "kind of special " way. Allow me to provide a bit of background: Each Invoice is conformed by several SubInvoice (s), and each SubInvoice is conformed by several InvoiceItem (s), which contain a break down of the Products purchased by a customer. Logically speaking, it'd be something like this (hopefully the ascii art works) +---------- Invoice id=3 -----------+ | Full total: $100.00 | | | | +----- Sub Invoice id=1 -----+ | | | Subtotal $70 | | | | | | | | Item 1 in SubInv.1 | | | | Item 2 in SubInv.1

An example Many-to-Many through relationship in Django: class First(models.Model): seconds = models.ManyToManyField(Second, through='Middle') class Middle(models.Model): first = models.ForeignKey(First) second = models.ForeignKey(Second) class Second(models.Model): Following the documentation on intermediary models , only one model of the pair to be related contains the ManytoManyField , model First in the example above. Is this correct? If so, which model should contain the ManytoManyField field? Are there any differences in using the relationship from either end depending on where the

I have a: has_and_belongs_to_many :friends, :join_table => "friends_peoples". To add a friend I do: @people.followers << @friend which create the relationship and a new person profile. Now I'd like to delete the relationship ONLY and not the person profile. I tried @people.friends.delete(guilty.id) but it deletes the person profile and not the relationship. Any idea? Have you tried this? @people.friends.delete(guilty) 来源： https://stackoverflow.com/questions/3852017/delete-a-has-many-relationship-only

I’ve looked all over the SQLAlchemy tutorial and other similar questions but I seem to be struggling to get this join to work: The scenario : I have a pages table represented by the Page model. Pages can be created by an user and edited by an user, but not necessarily the same one. My Page model looks like this (abridged): 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

Is there a way to adjust the bubble size (or colour) of nodes in Neo4j in relation to a node property value? For example, if each node has a size: "xxx" property, how would I make each node scale to this size? Is there a similar way to adjust relation lines? I know both nodes and relations can be adjusted to different colours or sizes all at once, but I can't figure out how to do this based on their properties. I tried creating a custom GRASS file, but weird things happened. This is what I used: node { diameter: 50px; color: #A5ABB6; border-color: #9AA1AC; border-width: 2px; text-color