code-first

I've recently downloaded Entity Framework Code First CTP5 , and have a trouble with this scenario. I have two tables as follows: Members table : ID Name Comments table : ID Comment CommentedMemberID CommentMemberID And, the data should be like the following: Members ID Name 1 Mike 2 John 3 Tom Comments ID Comment CommentedMemberID CommentMemberID 1 Good 1 2 2 Good 1 3 3 Bad 2 1 Then, I coded as shown below: public class Member { public int ID {get; set; } public string Name { get; set;} public virtual ICollection<Comment> Comments { get; set;} } public class Comment { public int ID { get; set;

I would like to use a lazy-loading collection on a model, but I want Add/Remove functionality to be done through separate methods. So something like this: class Model { protected virtual ICollection<Something> _somethings { get; set; } public IEnumerable<Something> Somethings { get { return _somethings; } } public void AddSomething(Something thingToAdd) { /* logic */ _somethings.Add(thingToAdd); } } I can't figure out how to configure the mapping for this. I looked into using a configuration class: EntityConfiguration. But since the property is protected I can't figure out how to set a

I made a in my model and updated database using Add-Migration sdfgfsd Update-Database Now I found the change I just made is not necessary. I would like do revert both code and database. How can I do this? Yes - it's straightforward. Use Update-Database -TargetMigration:zzzz Where zzzz is the name of the migration before the one you want to rollback. EDIT You then need to delete the migration(s) after zzzz. If you want to rollback all migrations, or if you only have one migration, use update-database -target:0 来源： https://stackoverflow.com/questions/30506137/revert-database-in-entity-framework

I have a model like public class User { [Key] public long UserId { get; set; } [Required] public String Nickname { get; set; } public virtual ICollection<Group> Memberships { get; set; } } public class Group { [Key] public long GroupId { get; set; } [Required] public String Name { get; set; } public virtual ICollection<User> Members { get; set; } } public class DataContext : DbContext { public DbSet<User> Users { get; set; } public DbSet<Group> Groups { get; set; } public DataContext() { Configuration.LazyLoadingEnabled = true; } protected override void OnModelCreating(DbModelBuilder

I'm working to solve a very tedious problem. I have a class called Nation and a class called NationAlly public class Nation { public int ID {get; set;} public int name {get;set;} public List<NationAlly> NationAllies {get;set;} } public class NationAlly { public int ID {get; set;} public int level {get;set;} public Nation toNation {get;set;} } I'm using EF 4 and CodeFirst with a DbContext called NationsDB to manage my database on SQL Server 2008. If I create a new object of type Nation and I try to call nationsDB.SaveChanges, I got the following exception: "Multiplicity constraint violated. The

Using code-first Entity Framework and .NET 4, I'm trying to create a one-to-many relationship between parents to children: public class Parent { [Key] public int ParentId { get; set; } [Required] public string ParentName { get; set; } public IEnumerable<Child> Children { get; set; } } public class Child { [Key] public int ChildId { get; set; } [ForeignKey] public int ParentId { get; set; } [Required] public string ChildName { get; set; } } As pointed out here , in order for foreign key relationship to carry into the database, the actual objects must be linked, not just their IDs. The normal