one-to-many

Let's first describe my situation. I am using Symfony2 and I have a problem with a relationship between my entities. I have two entities that are linked together. The two entities are AssociationQuestion and AssociationPossibleAnswer . I am currently creating a questionary software where one would have to link one possible answer on the left to another one possible answer on the right, such as in the following example: Currently, I'm planning on having two attributes that are arrays in class AssociationQuestion that would hold many AssociationPossibleAnswer objects. The first array would

Not sure what I'm doing wrong here. School has a to-many to Student, and Student has its inverse. A little test code as follows: @class Student; @interface School : NSManagedObject @property (nonatomic, retain) NSString * name; @property (nonatomic, retain) NSOrderedSet *students; @end @interface School (CoreDataGeneratedAccessors) - (void)insertObject:(Student *)value inStudentsAtIndex:(NSUInteger)idx; - (void)removeObjectFromStudentsAtIndex:(NSUInteger)idx; - (void)insertStudents:(NSArray *)value atIndexes:(NSIndexSet *)indexes; - (void)removeStudentsAtIndexes:(NSIndexSet *)indexes; - (void

I have several many to many relationships in my schema. For example, a package has many taskgroups, taskgroups in turn have many tasks. All tables are linked together via many to many tables, holding for instance the primary key of package and the primary key of taskgroup. (I know this is not strictly needed, since XML is one to many, but I couldn't think of a better structure). Is it possible to get the query result as XML, reflecting the one-to-many structure? So, the result should be like this: <package id=1> <taskgroup id=1> <task id=1> <task id=2> </taskgroup> <taskgroup id=2> <task id=3>

OneToMany + MapKeyJoinColumn doesn't work for me, please suggest what I'm doing wrong. I'm using JPA 2.0 + Hibernate 3.6.1 And want to map following tables: To Classes: @Entity public class Question { // id and other fields @OneToMany(mappedBy="question", cascade = CascadeType.ALL) @MapKeyJoinColumn(name="language_id") private Map<Language, Statement> statements = new HashMap<Language, Statement>(); } @Entity public class Statement { @Id private Long id; @ManyToOne @JoinColumn(name = "language_id", nullable = true) private Language language; @ManyToOne @JoinColumn(name = "question_id",

I have entities User and GrantedRole that have a bidirectional one-to-many relation. When I try to add a GrantedRole to the Set in User, there is no exception thrown, but when I debug the variables for the User and GrantedRole object have a description that reads com.sun.jdi.InvocationException occurred invoking method. The different fields for the variables can be read while debugging, but when I select the roles field in User or the user field in GrantedRole I get the same description as above. When I go into the Set of GrantedRole in user, I eventually find the following description: Detail

I'm working on my small project which take pictures and save them, very simple, using Core Data. I have two entities; one is 'Person' and the other is 'Image'. the relationship from Person to Image is to-many and from Image to Person I got inverse relationship as well. All I need at the moment is to add multiple number of images (taken from iphone camera or chosen from library) to one Person entity . I'd like to know whether there is any kind of sample code that deals with to-many relationship with UIImage using Core Data. many thanks. ===================== Actually I wish I could specify the