實體框架：ObjectContext和繼承

Question

我需要對我的類（CompetenceSpecific）進行CRUd操作。 競爭力有三個派生類 - CompetenceFunction，CompetenceArea和CompetenceSpecifc

The error I recieved: 
    There are no EntitySets defined for the specified entity type 'CompetencyManagement.Domain.Entities.CompetenceFunction'. If 'CompetencyManagement.Domain.Entities.CompetenceFunction' is a derived type, use the base type instead. Parameter name: TEntity 

我應該如何糾正呢？請提出解決方案，以解決我的問題。謝謝

請檢查下面的代碼，爲簡單起見，我刪除了部分代碼。

--model

public class Competence 
{ 
    public int CompetenceID { get; set; } 
    public int CourseID { get; set; } 
... 
} 

public class CompetenceFunction : Competence 
{ 

} 

--REPOSITORY和接口

public interface IRepository<T> where T : class 
{ 
    T GetById(object id); 
    IEnumerable<T> GetAll(); 
    IEnumerable<T> Query(Expression<Func<T, bool>> filter); 
    void Add(T entity); 
    void Remove(T entity); 
} 

public abstract class Repository<T> : IRepository<T> 
    where T : class 
{ 
    protected IObjectSet<T> _objectSet; 

    public Repository(ObjectContext context) 
    { 
     _objectSet = context.CreateObjectSet<T>(); 
    } 
... 
} 


public class CompetenceFunctionRepository : Repository<CompetenceFunction> 
{ 
    public CompetenceFunctionRepository(ObjectContext context) 
     : base(context) 
    { 
    } 

    public override CompetenceFunction GetById(object id) 
    { 
     return _objectSet.SingleOrDefault(s => s.CompetenceID == (int)id); 
    } 
} 

--unit工作

public interface IUnitOfWork 
{ 
    IRepository<CompetenceFunction> CompetenceFunctions { get; } 
    IRepository<CompetenceArea> CompetenceAreas { get; } 
    IRepository<CompetenceSpecific> CompetenceSpecifics { get; } 
    void Commit(); 
} 

public class UnitOfWork : IUnitOfWork, IDisposable 
{ 
    private CompetenceFunctionRepository _competencefunction; 
    private CompetenceAreaRepository _competencearea; 
    private CompetenceSpecificRepository _competencespecifc; 

    public UnitOfWork(ObjectContext context) 
    { 
     if (context == null) 
     { 
      throw new ArgumentNullException("Context was not supplied"); 
     } 

     _context = context; 
    } 

    #region IUnitOfWork Members 


    public IRepository<CompetenceFunction> CompetenceFunctions 
    { 
     get 
     { 
      if (_competencefunction == null) 
      { 
       _competencefunction = new CompetenceFunctionRepository(_context); 
      } 

      return _competencefunction; 
     } 
    } 

    public IRepository<CompetenceArea> CompetenceAreas 
    { 
     get 
     { 
      if (_competencearea == null) 
      { 
       _competencearea = new CompetenceAreaRepository(_context); 
      } 

      return _competencearea; 
     } 
    } 

    public IRepository<CompetenceSpecific> CompetenceSpecifics 
    { 
     get 
     { 
      if (_competencespecifc == null) 
      { 
       _competencespecifc = new CompetenceSpecificRepository(_context); 
      } 

      return _competencespecifc; 
     } 
    } 

--Im獲得在庫

的這部分的錯誤

public Repository(ObjectContext context) 
    { 
     _objectSet = context.CreateObjectSet<T>(); 
    } 


    There are no EntitySets defined for the specified entity type 'CompetencyManagement.Domain.Entities.CompetenceFunction'. If 'CompetencyManagement.Domain.Entities.CompetenceFunction' is a derived type, use the base type instead. Parameter name: TEntity 

這是我在控制器

private IUnitOfWork _unitOfWork; 
var a = _unitOfWork.CompetenceFunctions.GetAll(); 
return View(a); 

Answer 1

你必須得到由OfType功能派生類型，例如如何實現

context.CreateObjectSet<Competence>().OfType<CompetenceFunction>() 

在你的情況下，這意味着只有一個CompetenceRepository服務於Competence的所有衍生產品。

---

編輯

（您的評論後）
首先，UOW是指用於暫時存儲應在一個批次進行處理（如被提交到數據庫的更改）。 GetAll和類似的功能是存儲庫的東西。

但您是否需要知識庫？我喜歡this post。當開始瞭解EF時，我會關注EF的來龍去脈，而不會被周圍的架構過分分散注意力。例如。從內部直接與上下文進行通信並公開諸如GetCompetenceFunctions，GetCompetenceAreas（使用OfType）和SaveCompetenceFunction，...的方法。

您可以直接從MVC控制器中的操作方法處理這些服務方法。