one-to-one

问题 I am having a really hard time exploiting HasOne mapping with Fluent NHibernate. Basically, the class A can have a matching (only one or none) record in the class B. Please help with the AMap and BMap classes that define the relationships. Thank you. public class A { public virtual int Id {get;set;} public virtual string P1 {get;set;} public virtual string P2 {get;set;} public virtual string P3 {get;set;} } public class B { public virtual int Id {get;set;} public virtual string P4 {get;set;}

问题 I have these simple classes Class A(models.Model): ... Class Meta(models.Model): a = models.OnetoOneField(A, primary_key=True) width = models.IntegerField(default=100) but when I do a = A() meta = Meta() a.save() meta.a = a meta.save() print a.meta.width i get 'A' object has no attribute 'meta' Why is this? Am I using OneToOne wrong? if so how can i get the correct print statement? Thanks 回答1: Define a related_name to call the reverse accessor. a = models.OneToOneField(A, related_name='foobar

问题 I have these simple classes Class A(models.Model): ... Class Meta(models.Model): a = models.OnetoOneField(A, primary_key=True) width = models.IntegerField(default=100) but when I do a = A() meta = Meta() a.save() meta.a = a meta.save() print a.meta.width i get 'A' object has no attribute 'meta' Why is this? Am I using OneToOne wrong? if so how can i get the correct print statement? Thanks 回答1: Define a related_name to call the reverse accessor. a = models.OneToOneField(A, related_name='foobar

问题 I have these simple classes Class A(models.Model): ... Class Meta(models.Model): a = models.OnetoOneField(A, primary_key=True) width = models.IntegerField(default=100) but when I do a = A() meta = Meta() a.save() meta.a = a meta.save() print a.meta.width i get 'A' object has no attribute 'meta' Why is this? Am I using OneToOne wrong? if so how can i get the correct print statement? Thanks 回答1: Define a related_name to call the reverse accessor. a = models.OneToOneField(A, related_name='foobar

问题 So, this is my first time learning computer language. And I chose python and django. Now, I got many of the basic concepts of python and also django. I can create new page with the views and all other stuff. But I am still confused with the relations, i.e. one to one, many to one, and many to many. Will someone please please please explain it to me. How can I use it? I really need to know. Thanks. 回答1: Especially with django, which makes complicated db design a piece of cake, I think it's

问题 I want to create One-To-One relationship in EF where Foreign Keys can be null (So, It can be called 0..1-to-0..1) public class ProductInstance { public int Id { get; set; } public int SaleId { get; set; } public Sale Sale { get; set; } } public class Sale { public int Id { get; set; } public ProductInstance ProductInstance { get; set; } } FluentAPI configuration: modelBuilder.Entity<Sale>() .HasOptional(x => x.ProductInstance) .WithOptionalPrincipal(x => x.Sale); But it's generate two columns

问题 I've found a similar question but the reported solution didn't work for me. Here is the link: FOSUserBundle One-To-One mapped Entity not saved Probably I'm missing something. Current situation: I'm using the FOSUserBundle to register new users. The users' data are split between two tables with corresponding Entities and ONE TO ONE relation (one table contains the authentication credentials and the other one the users' profile data like name/surname etc). I've overwritten the basic

问题 Context: I used queryDSL in API controller which binds query to the database get. Currently, I have two tables with OneToOne relationship, and we can call them Table A and Table B. If there are 3 rows in A and 2 rows in B, when I get list A with some conditions, and the queryDSL will generate query SQL like A CROSS JOIN B WHERE A.id=B.a_id , but it will miss one item in A. Thus, I am going to implement custom repository to support change join type when generating the SQL statement. The

问题 I am trying to add a connection to a RestKit mapping but without success. My JSON is as follows: { parent: { token: "token" title: "title", description: "description", child_id: 1 } } My CoreData scheme defines that the Parent ManagedObject has a Child relation under the child key (and the opposite). The Parent mapping happens after I already have a corresponding Child object in CoreData, so that's not a problem. I followed some links and discussions around the web in order to solve this, but

问题 I'm using EF4.3.1 code first, I have the code as below, namespace ConsoleApplication5 { class Program { static void Main(string[] args) { using (var context = new myContext()) { TestA ta = new TestA(); ta.Name = "Hero"; TestB tb = new TestB(); tb.Name = "Allen"; TestC tc = new TestC(); tc.Name = "Iverson"; ta.tb = tb; ta.tc = tc; context.testASet.Add(ta); } } } class TestA { public int ID { get; set; } public string Name { get; set; } public TestB tb { get; set; } public TestC tc { get; set;