Is it possible to map composite primary key as single Value Object in Entity Framework Core? And then: does it work properly in LINQ queries?
I know that prior to EF Core 2.2 support of VO was not very good.
public class AssignmentIdentity
{
// ...
public EmployeeIdentity EmployeeId { get; protected set }
public TaskIdentity TaskId { get; protected set; }
}
public class Assignment
{
// ...
public AssignmentIdentity Id { get; protected set }
}
public class EmployeeIdentity
{
// ...
public String Identifier { get; protected set }
}
public class Employee
{
// ...
public EmployeeIdentity Id { get; protected set }
}
public class TaskIdentity
{
// ...
public String Identifier { get; protected set }
}
public class Task
{
// ...
public TaskIdentity Id { get; protected set }
}
Is it possible to map it in EF? Please, note that such mapping and LINQ querying is possible in (n)Hibernate. I would expect the same with EF Core...
Related
I have a class named Owner that has a BitString property:
public class Owner
{
public BitString Mask { get; set; }
}
where BitString is a class that contains a list of BitStringSegments:
public class BitString
{
public List<BitStringSegment> Segments;
}
public class BitStringSegment
{
public long BitMask { get; set; }
public int MaskIndex { get; set; }
}
I want to map this using EF Core's Fluent API such that the BitString property named Mask is an Owned property of the class named Owner, and the BitMaskSegments of Mask are mapped to their own table, but I am unsure of the syntax to make it work properly.
public class OwnerConfiguration : IEntityTypeConfiguration<Owner>
{
public virtual void Configure(EntityTypeBuilder<Owner> builder)
{
builder.OwnsOne(x => x.Mask, b =>
{
b.WithOwner();
b.OwnsMany(s => s.Segments)
.ToTable("BitMaskSegments")
.WithOwner();
}).Navigation(x => x.Mask).IsRequired();
}
}
I am using Entity Framework 6 Code First for my project.
Entities have Inheritance so I am following TPH(Table per Hierarchy).
I read following Article and many others.
None of them explain a way in which I can use an existing DB Column mapped to a property in Base Entity as Discriminator.
Based on the sample below I get following Exception
One or more validation errors were detected during model generation:
TaskType: Name: Each property name in a type must be unique. Property name 'TaskType' is already defined.
I think EF's auto generated Discriminator and my Entities Mapping is Conflicting.
Is there a possible way to instruct EF to not auto generate column and use Entity mapped Column.
If not, is there any explanation of this can not be avoided.
Peace.
I have Entities in following format
public enum TaskType
{
Random = 0,
Polished = 1,
Dropping = 2
}
public interface ITask
{
int Id { get; set; }
string Name { get; set; }
TaskType typeofTask { get; set; }
}
public abstract class BaseTask : ITask
{
public BaseTask(string name, TaskType type)
{
this.Name = Name;
this.typeofTask = type;
}
public int Id { get; set; }
public string Name { get; set; }
public TaskType typeofTask { get; set; }
}
public class RandomTask : BaseTask
{
public RandomTask() : base("My Random", TaskType.Random)
{
}
public int Owner { get; set; }
}
public class PolishedTask : BaseTask
{
public PolishedTask() : base("My Polished", TaskType.Polished)
{
}
}
public class DBContextTest : DbContext
{
public DBContextTest(string connection) : base(connection)
{
}
public DbSet<BaseTask> Task { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<BaseTask>().Map<RandomTask>(m => m.Requires("TaskType").HasValue(1))
.Map<PolishedTask>(m => m.Requires("TaskType").HasValue(1));
modelBuilder.Entity<BaseTask>().Property(p => p.typeofTask).HasColumnName("TaskType");
}
}
class Program
{
static void Main(string[] args)
{
try
{
DBContextTest dataContext = new DBContextTest("Server = (localdb)\\mssqllocaldb;DataBase = LOC2;Trusted_Connection = True;");
RandomTask randomtask = new RandomTask();
PolishedTask polishedTask = new PolishedTask();
dataContext.Task.Add(randomtask);
dataContext.Task.Add(polishedTask);
dataContext.SaveChanges();
}
catch (System.Exception ex)
{
}
}
}
Remove TaskType from your entity and let EF manage that as part of the TPH mapping. To differentiate types if you're dealing with a base-class collection, use .OfType<PolishedTask>() rather than .Where(x => x.TaskType == TaskType.Polished) EF should take care of the rest. If you do want it on the entity, create a non-mapped property in your sub-classes.
I.e.
public abstract class BaseTask
{
[NotMapped]
public abstract TaskType TaskType { get; }
}
public class PolishedTask
{
[NotMapped]
public override TaskType TaskType => TaskType.Polished
// or
//public override TaskType TaskType
//{
// get { return TaskType.Polished; }
//}
}
I am facing following issue: I have ProductOrder class which has ProductId as foreign key to Product class. When I invoke following method:
public IEnumerable<ProductOrder> GetOrders()
{
return OddzialDb.ProductOrders;
}
Orders are associated with Product so I can write something like this:
OddzialDb.ProductOrders.First().Product.Name;
but when it reaches Client it turns out that there is no association with Product which is null (only ProductId is included). In DbContext I have set
base.Configuration.ProxyCreationEnabled = false;
base.Configuration.LazyLoadingEnabled = false;
On the WCF Service side auto-generated by EF ProductOrder class looks as follows:
public partial class ProductOrder
{
public int Id { get; set; }
public Nullable<int> ProductId { get; set; }
public int Quantity { get; set; }
public virtual Product Product { get; set; }
}
What happens that it looses connections with tables associated by foreign keys?
Make your relationship virtual as in the example:
public class ProductOrder
{
public int Id { get; set; }
public virtual Product Product { get; set; }
public int ProductId { get; set; }
}
By turning your relationship virtual, the Entity Framework will generate a proxy of your ProductOrder class that will contain a reference of the Product.
To make sure it will work, Product also has to contain reference to ProductOrder:
public class Product
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<ProductOrder> ProductOrders { get; set; }
}
Set these variables true on your DbContext:
Configuration.LazyLoadingEnabled = true;
Configuration.ProxyCreationEnabled = true;
On your WCF application, add the following class, which will allow for proxy serialization:
public class ApplyDataContractResolverAttribute : Attribute, IOperationBehavior
{
public ApplyDataContractResolverAttribute()
{
}
public void AddBindingParameters(OperationDescription description, BindingParameterCollection parameters)
{
}
public void ApplyClientBehavior(OperationDescription description, System.ServiceModel.Dispatcher.ClientOperation proxy)
{
DataContractSerializerOperationBehavior dataContractSerializerOperationBehavior =
description.Behaviors.Find<DataContractSerializerOperationBehavior>();
dataContractSerializerOperationBehavior.DataContractResolver =
new ProxyDataContractResolver();
}
public void ApplyDispatchBehavior(OperationDescription description, System.ServiceModel.Dispatcher.DispatchOperation dispatch)
{
DataContractSerializerOperationBehavior dataContractSerializerOperationBehavior =
description.Behaviors.Find<DataContractSerializerOperationBehavior>();
dataContractSerializerOperationBehavior.DataContractResolver =
new ProxyDataContractResolver();
}
public void Validate(OperationDescription description)
{
// Do validation.
}
}
Then on your ServiceContract interfaces you add the DataAnnotation [ApplyDataContractResolver] right among your other annotations such as [OperationContract], above any method signature that returns an entity:
[OperationContract]
[ApplyDataContractResolver]
[FaultContract(typeof(AtcWcfEntryNotFoundException))]
Case GetSingleByCaseNumber(int number);
Using Model-first and Table-per-heirachy, I can create two classes that inherit from the same base class, and map a column in each of the two derived classes to the same table column so that I can 're-use' columns.
If I try that with Code-first, I get the following error: "Each property name in a type must be unique. Property name 'XXX' was already defined."
I assume that this is a bug in code-first?
Here is some example code:
public class Parent
{
public Guid Id { get; set; }
}
public class ChildA : Parent
{
public Int32 ChildAProperty { get; set; }
}
public class ChildB : Parent
{
public Int32 ChildBProperty { get; set; }
}
public class TestContext : DbContext
{
public DbSet<Parent> Entities { get { return this.Set<Parent>(); } }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
var childAConfig = modelBuilder.Entity<ChildA>();
childAConfig.Property(p => p.ChildAProperty).HasColumnName("Property");
var childBConfig = modelBuilder.Entity<ChildB>();
childBConfig.Property(p => p.ChildBProperty).HasColumnName("Property");
}
}
I'm creating a POCO model to use with entity framework code first CTP5. I'm using the decoration to make a property map to a PK column. But how can I define a PK on more then one column, and specifically, how can I control order of the columns in the index? Is it a result of the order of properties in the class?
Thanks!
NOTE:
As of 2019 this answer became non-valid for later EntityFramework versions.
You can specify the column order in the attributes, for instance:
public class MyEntity
{
[Key, Column(Order=0)]
public int MyFirstKeyProperty { get; set; }
[Key, Column(Order=1)]
public int MySecondKeyProperty { get; set; }
[Key, Column(Order=2)]
public string MyThirdKeyProperty { get; set; }
// other properties
}
If you are using the Find method of a DbSet you must take this order for the key parameters into account.
To complete the correct answer submitted by Slauma, you can use the HasKey method to specify an order for composite primary keys as well:
public class User
{
public int UserId { get; set; }
public string Username { get; set; }
}
public class Ctp5Context : DbContext
{
public DbSet<User> Users { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<User>().HasKey(u => new
{
u.UserId,
u.Username
});
}
}
If, like me, you prefer to use a configuration file you can do that in this way (based on Manavi's example):
public class User
{
public int UserId { get; set; }
public string Username { get; set; }
}
public class UserConfiguration : EntityTypeConfiguration<User>
{
public UserConfiguration()
{
ToTable("Users");
HasKey(x => new {x.UserId, x.Username});
}
}
Obviously you have to add the configuration file to your context:
public class Ctp5Context : DbContext
{
public DbSet<User> Users { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Configurations.Add(new UserConfiguration());
}
}
Use as a anonymous object:
modelBuilder.Entity<UserExamAttemptQuestion>().ToTable("Users").HasKey(o => new { o.UserId, o.Username });