In my case am not allowed to modify existing tables but I discovered that when you add a new table with “Include foreign key columns in the model” checked in EF4 and the table doesn’t contain any foreign key relationships then you try to add a association it will trigger this error. Defining Constraints in … Read more
@ManyToMany to self is rather confusing because the way you’d normally model this differs from the “Hibernate” way. Your problem is you’re missing another collection. Think of it this way – if you’re mapping “author”https://stackoverflow.com/”book” as many-to-many, you need “authors” collection on Book and “books” collection on Author. In this case, your “User” entity represents … Read more
Both mappings will create exactly the same database schema with a non-nullable foreign key SomethingId and a referential constraint between the two related tables. The first mapping with MapKey is used when you don’t want to have the foreign key as a property in your model class. The type of association in this case is … Read more
ManyToManyRel is used by the ManyToManyField to implement the relationship object for the Field base class which it extends. If you were to create a new field class that extended the Field class and contained a many-to-many relationship you might find this class convenient but it should not be used in your models (which is … Read more
There’s a really good treatment of relationship loops in chapter 3 of this paper (archive.org). Generally however, the most common issue with loops is consistency of redundant information. Consider the case (from the paper) where a parent has many children; each child attends a school. There is a third relationship between parent & school (‘parent … Read more
Hibernate uses a strategy called inspection, which is basically this: when an object is loaded from the database a snapshot of it is kept in memory. When the session is flushed Hibernate compares the stored snapshot with the current state. If they differ the object is marked as dirty and a suitable SQL command is … Read more
Go to “Database” Menu option Select the “Reverse Engineer” option. A wizard will be open and it will generate the ER Diagram for you.
— Disable the constraints on a table called tableName: ALTER TABLE tableName NOCHECK CONSTRAINT ALL — Re-enable the constraints on a table called tableName: ALTER TABLE tableName WITH CHECK CHECK CONSTRAINT ALL ——————————————————— — Disable constraints for all tables in the database: EXEC sp_msforeachtable ‘ALTER TABLE ? NOCHECK CONSTRAINT ALL’ — Re-enable constraints for all … Read more
Make a separate set of /memberships/ resources. REST is about making evolvable systems if nothing else. At this moment, you may only care that a given player is on a given team, but at some point in the future, you will want to annotate that relationship with more data: how long they’ve been on that … Read more