EntityFramework代码第一个键

Question

I have following tables: User, UserGroups, and UserInGroups. You can see them on picture below. When i call User i want to be able to get Groups that user is in (UserInGroups). I am reading materials about EntityFramework but i am unable to make connections in code to to that, what am i missing? Do i need to connect them onModelCreating?

Currently i am not getting any data from UserInGroup or UserGroups.

DB looks like this

My classes look like this:

public class User : BaseEntity
{
    public int RoleId { get; set; }

    public Role Role { get; set; }

    public UserGroup UserGroup { get; set; }

    public UserInGroup UserInGroup { get; set; }

}

public class UserGroup : BaseEntity
{
    public UserGroup()
    {
        Users = new List<User>();
        UserInGroups = new List<UserInGroup>();
    }

    [StringLength(255)]
    public string Name { get; set; }

    public string KeyName { get; set; }

    public List<User> Users { get; set; }

    public List<UserInGroup> UserInGroups { get; set; }

}

public class UserInGroup : BaseEntity
{
    public UserInGroup()
    {
        Users = new List<User>();
        UserGroups = new List<UserGroup>();
    }

    public int UserId { get; set; }

    public User User { get; set; }

    public int UserGroupId { get; set; }

    public UserGroup UserGroup { get; set; }

    public List<User> Users { get; set; }

    public List<UserGroup> UserGroups { get; set; }

}

DbContext:

public DbSet<GlobalSettings> GlobalSettings { get; set; }
    public DbSet<Role> Roles { get; set; }
    public DbSet<User> Users { get; set; }
    public DbSet<UserGroup> UserGroups { get; set; }
    public DbSet<UserInGroup> UsersInGroups { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<GlobalSettings>().Property(x => x.Key).HasColumnAnnotation("Index", new IndexAnnotation(new[] { new IndexAttribute("Index_VariablenName") { IsClustered = false, IsUnique = true } }));
    }

Answer 1

public abstract partial class BaseEntity
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }
}

public class User : BaseEntity
{
    public string Username { get; set; }
    public string Title { get; set; }
    public FirstName { get; set; }
    public string LasName { get; set; }
    public Genders Gender { get; set; }
    public string Email { get; set; }
    public int RoleId { get; set; }
    public string TechUser { get; set; }
    public DateTime TechChangeDate { get; set; }
    public int TechVersion { get; set; }
    public bool IsDeleted { get; set; }

    public virtual Role Role { get; set; }
    public virtual ICollection<UserInGroup> UserInGroups { get; set; }
}

public class UserInGroup : BaseEntity
{
    public int UserId { get; set; }
    public int UserGroupId { get; set; }
    public string TechUser { get; set; }
    public DateTime TechChangeDate { get; set; }
    public int TechVersion { get; set; }
    public bool IsDeleted { get; set; }

    public virtual User User { get; set; }
    public virtual UserGroup UserGroup { get; set; }
}

public class UserGroup : BaseEntity
{
    public string Name { get; set; }
    public string KeyName { get; set; }
    public string TechUser { get; set; }
    public DateTime TechChangeDate { get; set; }
    public int TechVersion { get; set; }
    public bool IsDeleted { get; set; }
}

public class Role : BaseEntity
{
    public string Name { get; set; }
}

public enum Genders 
{
    Male = 1,
    Female = 2
}

Answer 2

You can use two methods to fill navigation properties. First is lazy-loading and second is explicit specifying of required properties.

For lazy-loading you should declare your navigation properties as virtual :

public class User : BaseEntity
{
    public int RoleId { get; set; }

    public virtual Role Role { get; set; }

    public virtual UserGroup UserGroup { get; set; }

    public virtual UserInGroup UserInGroup { get; set; }
}

public class UserGroup : BaseEntity
{
    public UserGroup()
    {
        Users = new HashSet<User>(); // HashSet is more effective than List
        UserInGroups = new HashSet<UserInGroup>();
    }

    [StringLength(255)]
    public string Name { get; set; }

    public string KeyName { get; set; }

    public virtual ICollection<User> Users { get; set; } // ICollection is less restrective

    public virtual ICollection<UserInGroup> UserInGroups { get; set; }
}

Now, you can load fe single user:

var justUser = dbContext.Users.Single(u => u.Id == 100);

When you need its properties they will by transparently loaded:

foreach (var userInGroup in user.UsersInGroups) // here is second loading
{
    . . .
}

The second way is the calling of the Include method to explicit specifying required properties:

var userWithGroups = dbContext.Users
                              .Include(u => u.UserInGroups) // include single navigation property
                              .Include(ugs => ugs.Groups.Select(ug => ug.Group)) // include collection navigation property
                              .Single(u => u.Id == 100); // get the user with specified id and filled specified properties