I have defined a set of Code First entities as such:
public class User
{
public int UserId { get; set; }
public string username { get; set; }
}
public abstract class UserType
{
public virtual User User { get; set; }
public int UserId { get; set; }
}
public class RoleUser : UserType
{
public string role { get; set; }
}
public class SiteUser : UserType
{
public string site { get; set; }
}
public class Testctx:DbContext
{
static Testctx()
{
Database.SetInitializer(new DropCreateDatabaseAlways<Testctx>());
}
public DbSet<User> Users { get; set; }
public DbSet<SiteUser> SiteUsers { get; set; }
public DbSet<RoleUser> RoleUsers { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<User>().HasKey(u=>u.UserId).ToTable("User");
modelBuilder.Entity<RoleUser>().HasKey(u => u.UserId).ToTable("RoleUser");
modelBuilder.Entity<SiteUser>().HasKey(u => u.UserId).ToTable("SiteUser");
}
}
If I wanted User, RoleUser, SiteUser, to each have a ID column named "ID" How can I achieve this while keeping the foreign primary key relationship to user in Usertype.
For instance if i declare public class Entity{ public int ID {get;set;}} and have all inherit from Entity, I'm left with a UserId and an ID field in RoleUser and SiteUser.
Related
Below are two tables that has a many to many relation and and also another table that has a relation with the two first. A mapping table is created by Visual Studio with the name OrderEmployee, but when I run the application and enter some information to the Timeunit create form, the mapping table OrderEmployee is empty!
Should there not be some IDs added to that table since it has a relation with the Timeunit table or how is this mapping table thing working, when will there be data added to the mapping table? Or is something wrong with my Entity Classes?
public class Order
{
public int ID { get; set; }
public string Name { get; set; }
public int? ManufacturerID { get; set; }
public virtual Manufacturer Manufacturer { get; set; }
public virtual ICollection<Employee> Employees { get; set; }
}
public class Employee
{
public int ID { get; set; }
public string Name { get; set; }
public int EmployeeNumber { get; set; }
public virtual ICollection<Timeunit> Timeunits { get; set; }
public virtual ICollection<Order> Order { get; set; }
}
public class Timeunit
{
public int ID { get; set; }
public int Week { get; set; }
public int HoursPerWeek { get; set; }
public int EmployeeID { get; set; }
public int? OrderID { get; set; }
public virtual Employee Employee { get; set; }
public virtual Order Order { get; set; }
}
EDIT:
Create Method for Timeunit:
public ActionResult Create([Bind(Include = "ID,Week,HoursPerWeek,EmployeeID,OrderID")] Timeunit timeunit)
{
if (ModelState.IsValid)
{
db.Timeunits.Add(timeunit);
db.SaveChanges();
return RedirectToAction("Index");
}
ViewBag.ProjectID = new SelectList(db.Orders, "ID", "Name", timeunit.OrderID);
ViewBag.ResourceID = new SelectList(db.Employees, "ID", "Name", timeunit.EmployeeID);
return View(timeunit);
}
I have a table in database which points to itself, i.e. parent_id >> category id. This is the ER diagram
I have modelled this table like following, but it gives *Error : 'Category': member names cannot be the same as their enclosing type :
public class Category
{
[Key]
public int category_id { get; set; }
public string category_name { get; set; }
public int category_parent { get; set; }
public string category_desc { get; set; }
public virtual Category Category { get; set; }
}
How should I model such tables ?
You have to make category_parent nullable and configure navigational property Category to the scalar property category_parent. Try to use proper naming convensions.
public class Category
{
[Key]
[Column("category_id")]
public int Id { get; set; }
[Column("category_name")]
public string Name { get; set; }
[Column("category_parent")]
public int? ParentId { get; set; }
[Column("category_desc")]
public string Description { get; set; }
[ForeignKey("ParentId")]
public virtual Category ParentCategory { get; set; }
}
I think you just need to change the Category property name to something else, so it is not the same as the class name...
public virtual Category SubCategory { get; set; }
public class Category
{
[Key]
public int category_id { get; set; }
public string category_name { get; set; }
public int category_parent { get; set; }
public string category_desc { get; set; }
public int parent_category_id { get; set; } <-- ADD & setup as foreign key
public virtual Category ParentCategory { get; set; } <-- Change name
public virtual ICollection<Category> Categories { get; set; }
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Category>.HasMany(cat => cat.Categories)
.WithRequired()
.HasForeignKey(cat => cat.parent_category_id);
}
I've looked through several of the questions here and am not quite connecting all the (mental) dots on this. I would appreciate some help.
My Models (code first):
public class cgArmorial
{
[Key]
[Display(Name = "Armorial ID")]
public Guid ArmorialID { get; set; }
[Display(Name = "User ID")]
public Guid UserId { get; set; }
public string Name { get; set; }
public string DeviceUrl { get; set; }
public string Blazon { get; set; }
public virtual ICollection<cgArmorialAward> ArmorialAwards { get; set; }
}
public class cgArmorialAward
{
public cgArmorial Armorial { get; set; }
public cgAward Award { get; set; }
public DateTime AwardedOn { get; set; }
}
public class cgAward
{
[Key]
[Display(Name = "Award ID")]
public Guid AwardID { get; set; }
public string Name { get; set; }
public string Group { get; set; }
public string Description { get; set; }
public string ImageUrl { get; set; }
public string Blazon { get; set; }
public virtual ICollection<cgArmorialAward> ArmorialAwards { get; set; }
}
Then in my Context class I have (last 2 entries):
public class Context : DbContext
{
public DbSet<cgUser> Users { get; set; }
public DbSet<cgEvent> Events { get; set; }
public DbSet<cgEventType> EventTypes { get; set; }
public DbSet<cgArmorial> Armorials { get; set; }
public DbSet<cgAward> Awards { get; set; }
public DbSet<cgArmorialAward> ArmorialAwards { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<cgUser>()
.HasMany<cgEvent>(e => e.EventAutocrats)
.WithMany(u => u.EventAutocrats)
.Map(m =>
{
m.ToTable("EventAutocrats");
m.MapLeftKey("UserId");
m.MapRightKey("EventId");
});
modelBuilder.Entity<cgUser>()
.HasMany<cgEvent>(e => e.EventStaff)
.WithMany(u => u.EventStaff)
.Map(m =>
{
m.ToTable("EventStaff");
m.MapLeftKey("UserId");
m.MapRightKey("EventId");
});
modelBuilder.Entity<cgArmorialAward>()
.HasRequired(a => a.Armorial)
.WithMany(b => b.ArmorialAwards);
modelBuilder.Entity<cgArmorialAward>()
.HasRequired(a => a.Award)
.WithMany(); // b => b.ArmorialAwards
}
}
I am getting this error when I try to run:
System.Data.Edm.EdmEntityType: : EntityType 'cgArmorialAward' has no
key defined. Define the key for this EntityType.
System.Data.Edm.EdmEntitySet: EntityType: EntitySet �ArmorialAwards�
is based on type �cgArmorialAward� that has no keys defined.
Well, as the exception says: You don't have a key defined on your entity cgArmorialAward. Every entity must have a key. Change it to the following:
public class cgArmorialAward
{
[Key, Column(Order = 0)]
[ForeignKey("Armorial")]
public Guid ArmorialID { get; set; }
[Key, Column(Order = 1)]
[ForeignKey("Award")]
public Guid AwardID { get; set; }
public cgArmorial Armorial { get; set; }
public cgAward Award { get; set; }
public DateTime AwardedOn { get; set; }
}
The fields in the composite key are foreign keys to the other two tables at the same time, hence the ForeignKey attribute. (I'm not sure if conventions would detect this automatically because you have non-standard names ("cgXXX" for the classes and "XXXId" for the foreign key properties). On the other hand the property names Armorial and Award match the foreign key property names. I'm not sure if EF conventions would consider this. So, perhaps the ForeignKey attribute is not necessary but at least it's not wrong.)
I have two entities that have a relationship for which I create a join table
public class Student
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<Image> Images { get; set; }
}
public class Image
{
public int Id { get; set; }
public string Filename { get; set; }
public virtual ICollection<Student> Students { get; set; }
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Student>()
.HasMany(i => i.Images)
.WithMany(s => s.Students)
.Map(m => m.ToTable("StudentImages"));
}
I would like to add an additional column to allow chronological ordering of the StudentImages.
Where should I add insert the relevant code?
Do you want to use that new column in your application? In such case you cannot do that with your model. Many-to-many relation works only if junction table doesn't contain anything else than foreign keys to main tables. Once you add additional column exposed to your application, the junction table becomes entity as any other = you need third class. Your model should look like:
public class StudentImage
{
public int StudentId { get; set; }
public int ImageId { get; set; }
public int Order { get; set; }
public virtual Student Student { get; set; }
public virtual Image Image { get; set; }
}
public class Student
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<StudentImage> Images { get; set; }
}
public class Image
{
public int Id { get; set; }
public string Filename { get; set; }
public virtual ICollection<StudentImage> Students { get; set; }
}
And your mapping must change as well:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<StudentImages>().HasKey(si => new { si.StudentId, si.ImageId });
// The rest should not be needed - it should be done by conventions
modelBuilder.Entity<Student>()
.HasMany(s => s.Images)
.WithRequired(si => si.Student)
.HasForeignKey(si => si.StudentId);
modelBuilder.Entity<Image>()
.HasMany(s => s.Students)
.WithRequired(si => si.Image)
.HasForeignKey(si => si.ImageId);
}
I want to created Bi-Directional One-One relationship between two entities using EF Code First. I have trouble with the following code. What do you think I should do?
public class User
{
public string ID { get; set; }
public string LastName { get; set; }
public string Password { get; set; }
public string FirstName { get; set; }
public int ProfileID { get; set; }
public Profile Profile { get; set; }
}
public class Profile
{
public int UserID { get; set; }
public User User { get; set; }
public int ProfileID { get; set; }
public string ProfileName { get; set; }
public DateTime CreateDate { get; set; }
public DateTime LastUpdateDate { get; set; }
}
I want to have both Navigation property and Foreign Key in both the entities.
This gives me error. What can do I in Fluent Mapping API to make this work?
Use this:
public class User
{
public string ID { get; set; }
public string LastName { get; set; }
public string Password { get; set; }
public string FirstName { get; set; }
public Profile Profile { get; set; }
}
public class Profile
{
[Key, ForeignKey("User")]
public int ProfileID { get; set; }
public string ProfileName { get; set; }
public DateTime CreateDate { get; set; }
public DateTime LastUpdateDate { get; set; }
public User User { get; set; }
}
That is the only valid way to build one-to-one relation in EF - PK of the dependent entity must be also FK to principal entity. There is nothing like bidirectional one-to-one relation in EF because it cannot work in EF.
The way how people sometimes overcome this are two one-to-many relations where principal doesn't have navigation collection for dependent entities + manually defined unique keys in the database. That require manual mapping:
public class User
{
public string ID { get; set; }
public string LastName { get; set; }
public string Password { get; set; }
public string FirstName { get; set; }
// one side MUST be nullable otherwise you have bidirectional constraint where each
// entity demands other side to be inserted first = not possible
public int? ProfileId { get; set; }
public Profile Profile { get; set; }
}
public class Profile
{
public int ProfileID { get; set; }
public string ProfileName { get; set; }
public DateTime CreateDate { get; set; }
public DateTime LastUpdateDate { get; set; }
public int UserId { get; set; }
public User User { get; set; }
}
And in mapping you will define:
modelBuilder.Entity<User>
.HasOptional(u => u.Profile)
.WithMany()
.HasForeignKey(u => u.ProfileId);
modelBuilder.Entity<Profile>
.HasRequired(u => u.User)
.WithMany()
.HasForeignKey(u => u.UserId);
Now you must define Unique keys in the database - if you are using code first use custom database initializer. Be aware that still bidirectional one-to-one is wrong concept because both sides demand unique FK where NULL is still included in unique values so once you insert User before Profile there mustn't be any other User without Profile. That probably leads to serializable transaction.