c# - 如何在 Entity Framework 应用程序的基类中实现 CRUD 操作？

Question

我正在开发一个简单的 EF/MVC 应用程序，我正在尝试实现一些存储库来处理我的实体。我已经设置了一个 BaseObject 类和一个 IBaseRepository 接口(interface)来处理最基本的操作，因此我不必每次都重复:

public abstract class BaseObject<T>
    {
        public XA.Model.Entities.XAEntities db;
        public BaseObject()
        {
            db = new Entities.XAEntities();
        }

        public BaseObject(Entities.XAEntities cont)
        {
            db = cont;
        }

        public void Delete(T entity)
        {
            db.DeleteObject(entity);
            db.SaveChanges();
        }

        public void Update(T entity)
        {
            db.AcceptAllChanges();
            db.SaveChanges();
        }
   }

    public interface IBaseRepository<T>
    {
        void Add(T entity);

        T GetById(int id);
        IQueryable<T> GetAll();
    }

但后来我发现自己必须在每个存储库中实现 3 个基本方法(Add、GetById 和 GetAll):

public class AgencyRepository : Framework.BaseObject<Agency>, Framework.IBaseRepository<Agency>
    {
        public void Add(Agency entity)
        {
            db.Companies.AddObject(entity);
            db.SaveChanges();
        }
        public Agency GetById(int id)
        {
            return db.Companies.OfType<Agency>().FirstOrDefault(x => x.Id == id);
        }
        public IQueryable<Agency> GetAll()
        {
            var agn = from a in db.Companies.OfType<Agency>()
                      select a;
            return agn;
        }
    }

我怎样才能将它们放入我的 BaseObject 类中，这样我就不会与 DRY 发生冲突。

Answer 1

嗨，我遇到了同样的问题。想出这样的解决方案

namespace ABC
{
    public class EntitiesRepository<T> : IDisposable where T : class
    {
        private ObjectContext _context;

        /// <summary>
        /// The IObjectSet that represents the current entity.
        /// </summary>
        private ObjectSet<T> _objectSet;

        public OperationStatus status { get; set; }

        /// <summary>
        /// Initializes a new instance of the DataRepository class
        /// </summary>
        public BilderQuizEntitiesRepository()
        {
            _context = new Entities();  //DBContext

            _objectSet = _context.CreateObjectSet<T>();
         }

        public T Select(int id)
        {
            EntityKey key = GetEntityKey(id);

            return (T)_context.GetObjectByKey(key);
        }

        public void Delete(T entity)
        {
            try
            {
                if (entity == null)
                {

                    throw new ArgumentNullException("entity");
                }

                EntityKey key = GetEntitySpecificKey(entity);
                T attachEntity = (T)_context.GetObjectByKey(key);
                _objectSet.DeleteObject(attachEntity);
                SaveChanges();                
            }
            catch
            {

            }

        }       

        public void Delete(int id)
        {
            EntityKey key = GetEntityKey(id);
            Delete((T)_context.GetObjectByKey(key));
            SaveChanges();
        }

        public void Update(T entity)
        {
            try
            {
                if (entity == null)
                {

                    throw new ArgumentNullException("entity");
                }

                EntityKey key = GetEntitySpecificKey(entity);
                T attachEntity = (T)_context.GetObjectByKey(key);
                _objectSet.Attach(attachEntity);
                _objectSet.ApplyCurrentValues(entity);
                SaveChanges();

            }
            catch
            {

            }

        }       

        /// <summary>
        /// Returns Entity Key 
        /// </summary>
        /// <param name="keyValue"></param>
        /// <returns></returns>
        private EntityKey GetEntityKey(object keyValue) //Get EnrityKey
        {
            var entitySetName = _context.DefaultContainerName + "." + _objectSet.EntitySet.Name;
            var keyPropertyName = _objectSet.EntitySet.ElementType.KeyMembers[0].ToString();
            var entityKey = new EntityKey(entitySetName, new[] { new EntityKeyMember(keyPropertyName, keyValue) });
            return entityKey;
        }

        /// <summary>
        /// Returns Entity Key 
        /// </summary>
        /// <param name="keyValue"></param>
        /// <returns></returns>
        private EntityKey GetEntitySpecificKey(T entity) //Get EnrityKey
        {
            Type objType = typeof(T);
            var keyPropertyName = _objectSet.EntitySet.ElementType.KeyMembers[0].ToString();
            var pi = objType.GetProperty(keyPropertyName);
            var keyValue = pi.GetValue(entity, null);
            var entitySetName = _context.DefaultContainerName + "." + _objectSet.EntitySet.Name;

            var entityKey = new EntityKey(entitySetName, new[] { new EntityKeyMember(keyPropertyName, keyValue) });
            return entityKey;
        }

        private string GetPrimaryKeyValue(T entity)
        {
            Type objType = typeof(T);
            var keyPropertyName = _objectSet.EntitySet.ElementType.KeyMembers[0].ToString();
            var pi = objType.GetProperty(keyPropertyName);
            var keyValue = pi.GetValue(entity, null);
            return keyValue.ToString();
        }

        /// <summary>
        /// Saves all context changes
        /// </summary>
        public bool SaveChanges()
        {
            return _context.SaveChanges() > 0 ? true : false;
        }

        /// <summary>
        /// Releases all resources used by the WarrantManagement.DataExtract.Dal.ReportDataBase
        /// </summary>
        public void Dispose()
        {

            Dispose(true);

            GC.SuppressFinalize(this);

        }

        /// <summary>
        /// Releases all resources used by the WarrantManagement.DataExtract.Dal.ReportDataBase
        /// </summary>
        /// <param name="disposing">A boolean value indicating whether or not to dispose managed resources</param>
        protected virtual void Dispose(bool disposing)
        {

            if (disposing)
            {

                if (_context != null)
                {

                    _context.Dispose();

                    _context = null;

                }

            }

        }
    }

}

如果你找到更好的方法，请告诉我