园子里的一个Dal类

public class DALHelper

    {

        public static List<T> Search<T>() where T : SH_SetBase

        {

            using (var db = new ShopContext())

            {

                var dbSet = GetDBSet(db, typeof(T)) as DbSet<T>;

                if (typeof(T).IsSubclassOf(typeof(SH_SetBase)))

                {

                    return dbSet.Where(o => !o.IsDelete).ToList();

                }

                return dbSet.ToList();

            }

        }

        public static List<T> Search<T>(Expression<Func<T, bool>> where) where T : SH_Base

        {

            using (ShopContext db = new ShopContext())

            {

                DbSet<T> dbSet = GetDBSet(db, typeof(T)) as DbSet<T>;

                if (typeof(T).IsSubclassOf(typeof(SH_SetBase)))

                {

                    Expression<Func<T, bool>> where2 = (o => (o as SH_SetBase).IsDelete == false);

                    var invokedExpr = Expression.Invoke(where2, where.Parameters.Cast<Expression>());

                    Expression<Func<T, bool>> where3 = Expression.Lambda<Func<T, bool>>(Expression.And(where.Body, invokedExpr), where.Parameters);

                    return dbSet.Where(where3.Compile()).ToList();

                }

                return dbSet.Where(where).ToList();

            }

        }

        public static List<T> Search<T>(Expression<Func<T, bool>> where, PageContent pageContent) where T : SH_Base

        {

            using (ShopContext db = new ShopContext())

            {

                DbSet<T> dbSet = GetDBSet(db, typeof(T)) as DbSet<T>;

                if (typeof(T).IsSubclassOf(typeof(SH_SetBase)))

                {

                    Expression<Func<T, bool>> where2 = (o => (o as SH_SetBase).IsDelete == false);

                    var invokedExpr = Expression.Invoke(where2, where.Parameters.Cast<Expression>());

                    Expression<Func<T, bool>> where3 = Expression.Lambda<Func<T, bool>>(Expression.And(where.Body, invokedExpr), where.Parameters);

                    where = where3;

                }

                pageContent.TotalLogs = Count<T>(where);

                return dbSet.Where(where.Compile()).Skip((pageContent.PageIndex - ) * pageContent.PageSize).Take(pageContent.PageSize).ToList();

            }

        }

        public static List<T> Search<T>(Expression<Func<T, object>> include, Expression<Func<T, bool>> where) where T : SH_Base

        {

            using (ShopContext db = new ShopContext())

            {

                DbSet<T> dbSet = GetDBSet(db, typeof(T)) as DbSet<T>;

                if (typeof(T).IsSubclassOf(typeof(SH_SetBase)))

                {

                    Expression<Func<T, bool>> where2 = (o => (o as SH_SetBase).IsDelete == false);

                    var invokedExpr = Expression.Invoke(where2, where.Parameters.Cast<Expression>());

                    Expression<Func<T, bool>> where3 = Expression.Lambda<Func<T, bool>>(Expression.And(where.Body, invokedExpr), where.Parameters);

                    return dbSet.Include(include).Where(where3.Compile()).ToList();

                }

                return dbSet.Include(include).Where(where).ToList();

            }

        }

        public static List<T> Search<T>(Expression<Func<T, object>> include, Expression<Func<T, bool>> where, PageContent pageContent) where T : SH_Base

        {

            using (ShopContext db = new ShopContext())

            {

                DbSet<T> dbSet = GetDBSet(db, typeof(T)) as DbSet<T>;

                if (typeof(T).IsSubclassOf(typeof(SH_SetBase)))

                {

                    Expression<Func<T, bool>> where2 = (o => (o as SH_SetBase).IsDelete == false);

                    var invokedExpr = Expression.Invoke(where2, where.Parameters.Cast<Expression>());

                    Expression<Func<T, bool>> where3 = Expression.Lambda<Func<T, bool>>(Expression.And(where.Body, invokedExpr), where.Parameters);

                    where = where3;

                }

                pageContent.TotalLogs = Count<T>(where);

                return dbSet.Include(include).Where(where.Compile()).Skip((pageContent.PageIndex - ) * pageContent.PageSize).Take(pageContent.PageSize).ToList();

            }

        }

        public static List<T> Search<T>(Expression<Func<T, bool>> where, PageContent pageContent, Expression<Func<T, object>> order, bool isAsc) where T : SH_Base

        {

            using (ShopContext db = new ShopContext())

            {

                DbSet<T> dbSet = GetDBSet(db, typeof(T)) as DbSet<T>;

                if (typeof(T).IsSubclassOf(typeof(SH_SetBase)))

                {

                    Expression<Func<T, bool>> where2 = (o => (o as SH_SetBase).IsDelete == false);

                    var invokedExpr = Expression.Invoke(where2, where.Parameters.Cast<Expression>());

                    Expression<Func<T, bool>> where3 = Expression.Lambda<Func<T, bool>>(Expression.And(where.Body, invokedExpr), where.Parameters);

                    where = where3;

                }

                pageContent.TotalLogs = Count<T>(where);

                if (isAsc)

                    return dbSet.Where(where.Compile()).OrderBy(order.Compile()).Skip((pageContent.PageIndex - ) * pageContent.PageSize).Take(pageContent.PageSize).ToList();

                else

                    return dbSet.Where(where.Compile()).OrderByDescending(order.Compile()).Skip((pageContent.PageIndex - ) * pageContent.PageSize).Take(pageContent.PageSize).ToList();

            }

        }

        public static List<T> Search<T>(Expression<Func<T, object>> include, Expression<Func<T, bool>> where, PageContent pageContent, Expression<Func<T, object>> order, bool isAsc) where T : SH_Base

        {

            using (ShopContext db = new ShopContext())

            {

                DbSet<T> dbSet = GetDBSet(db, typeof(T)) as DbSet<T>;

                if (typeof(T).IsSubclassOf(typeof(SH_SetBase)))

                {

                    Expression<Func<T, bool>> where2 = (o => (o as SH_SetBase).IsDelete == false);

                    var invokedExpr = Expression.Invoke(where2, where.Parameters.Cast<Expression>());

                    Expression<Func<T, bool>> where3 = Expression.Lambda<Func<T, bool>>(Expression.And(where.Body, invokedExpr), where.Parameters);

                    where = where3;

                }

                pageContent.TotalLogs = Count<T>(where);

                if (isAsc)

                    return dbSet.Include(include).Where(where.Compile()).OrderBy(order.Compile()).Skip((pageContent.PageIndex - ) * pageContent.PageSize).Take(pageContent.PageSize).ToList();

                else

                    return dbSet.Include(include).Where(where.Compile()).OrderByDescending(order.Compile()).Skip((pageContent.PageIndex - ) * pageContent.PageSize).Take(pageContent.PageSize).ToList();

            }

        }

        public static List<T> Search<T>(Expression<Func<T, object>> path1, Expression<Func<T, object>> path2, Expression<Func<T, bool>> where, PageContent pageContent, Expression<Func<T, object>> order, bool isAsc) where T : SH_Base

        {

            using (ShopContext db = new ShopContext())

            {

                DbSet<T> dbSet = GetDBSet(db, typeof(T)) as DbSet<T>;

                if (typeof(T).IsSubclassOf(typeof(SH_SetBase)))

                {

                    Expression<Func<T, bool>> where2 = (o => (o as SH_SetBase).IsDelete == false);

                    var invokedExpr = Expression.Invoke(where2, where.Parameters.Cast<Expression>());

                    Expression<Func<T, bool>> where3 = Expression.Lambda<Func<T, bool>>(Expression.And(where.Body, invokedExpr), where.Parameters);

                    where = where3;

                }

                pageContent.TotalLogs = Count<T>(where);

                if (isAsc)

                    return dbSet.Include(path1).Include(path2).Where(where.Compile()).OrderBy(order.Compile()).Skip((pageContent.PageIndex - ) * pageContent.PageSize).Take(pageContent.PageSize).ToList();

                else

                    return dbSet.Include(path1).Include(path2).Where(where.Compile()).OrderByDescending(order.Compile()).Skip((pageContent.PageIndex - ) * pageContent.PageSize).Take(pageContent.PageSize).ToList();

            }

        }

        public static bool Exist<T>(Expression<Func<T, bool>> where) where T : SH_Base

        {

            using (ShopContext db = new ShopContext())

            {

                DbSet<T> dbSet = GetDBSet(db, typeof(T)) as DbSet<T>;

                if (typeof(T).IsSubclassOf(typeof(SH_SetBase)))

                {

                    Expression<Func<T, bool>> where2 = (o => (o as SH_SetBase).IsDelete == false);

                    var invokedExpr = Expression.Invoke(where2, where.Parameters.Cast<Expression>());

                    Expression<Func<T, bool>> where3 = Expression.Lambda<Func<T, bool>>(Expression.And(where.Body, invokedExpr), where.Parameters);

                    return dbSet.FirstOrDefault(where3.Compile()) != null;

                }

                return dbSet.FirstOrDefault(where.Compile()) != null;

            }

        }

        public static int Count<T>(Expression<Func<T, bool>> where) where T : SH_Base

        {

            using (ShopContext db = new ShopContext())

            {

                DbSet<T> dbSet = GetDBSet(db, typeof(T)) as DbSet<T>;

                if (typeof(T).IsSubclassOf(typeof(SH_SetBase)))

                {

                    Expression<Func<T, bool>> where2 = (o => (o as SH_SetBase).IsDelete == false);

                    var invokedExpr = Expression.Invoke(where2, where.Parameters.Cast<Expression>());

                    Expression<Func<T, bool>> where3 = Expression.Lambda<Func<T, bool>>(Expression.And(where.Body, invokedExpr), where.Parameters);

                    return dbSet.Count(where3.Compile());

                }

                return dbSet.Count(where);

            }

        }

        public static decimal Sum<T>(Expression<Func<T, bool>> where, Expression<Func<T, decimal>> selector) where T : SH_Base

        {

            using (ShopContext db = new ShopContext())

            {

                DbSet<T> dbSet = GetDBSet(db, typeof(T)) as DbSet<T>;

                if (typeof(T).IsSubclassOf(typeof(SH_SetBase)))

                {

                    Expression<Func<T, bool>> where2 = (o => (o as SH_SetBase).IsDelete == false);

                    var invokedExpr = Expression.Invoke(where2, where.Parameters.Cast<Expression>());

                    Expression<Func<T, bool>> where3 = Expression.Lambda<Func<T, bool>>(Expression.And(where.Body, invokedExpr), where.Parameters);

                    return dbSet.Where(where3.Compile()).Sum(selector.Compile());

                }

                return dbSet.Where(where.Compile()).Sum(selector.Compile());

            }

        }

        public static int Sum<T>(Expression<Func<T, bool>> where, Expression<Func<T, int>> selector) where T : SH_Base

        {

            using (ShopContext db = new ShopContext())

            {

                DbSet<T> dbSet = GetDBSet(db, typeof(T)) as DbSet<T>;

                if (typeof(T).IsSubclassOf(typeof(SH_SetBase)))

                {

                    Expression<Func<T, bool>> where2 = (o => (o as SH_SetBase).IsDelete == false);

                    var invokedExpr = Expression.Invoke(where2, where.Parameters.Cast<Expression>());

                    Expression<Func<T, bool>> where3 = Expression.Lambda<Func<T, bool>>(Expression.And(where.Body, invokedExpr), where.Parameters);

                    return dbSet.Where(where3.Compile()).Sum(selector.Compile());

                }

                return dbSet.Where(where.Compile()).Sum(selector.Compile());

            }

        }

        public static T SearchObject<T>(Expression<Func<T, bool>> where) where T : SH_Base

        {

            using (ShopContext db = new ShopContext())

            {

                DbSet<T> dbSet = GetDBSet(db, typeof(T)) as DbSet<T>;

                if (typeof(T).IsSubclassOf(typeof(SH_SetBase)))

                {

                    Expression<Func<T, bool>> where2 = (o => (o as SH_SetBase).IsDelete == false);

                    var invokedExpr = Expression.Invoke(where2, where.Parameters.Cast<Expression>());

                    Expression<Func<T, bool>> where3 = Expression.Lambda<Func<T, bool>>(Expression.And(where.Body, invokedExpr), where.Parameters);

                    return dbSet.FirstOrDefault(where3.Compile());

                }

                return dbSet.FirstOrDefault(where.Compile());

            }

        }

        public static T Find<T>(long id) where T : SH_Base

        {

            using (ShopContext db = new ShopContext())

            {

                DbSet<T> dbSet = GetDBSet(db, typeof(T)) as DbSet<T>;

                if (typeof(T).IsSubclassOf(typeof(SH_SetBase)))

                {

                    SH_SetBase model = dbSet.Find(id) as SH_SetBase;

                    if (model != null && !model.IsDelete)

                        return model as T;

                }

                return dbSet.Find(id) as T;

            }

        }

        public static bool Save(SH_Base model)

        {

            using (ShopContext db = new ShopContext())

            {

                object dbSet = GetDBSet(db, model);

                if (model.ID == )

                {

                    CallMethod(dbSet, "Add", new object[] { model });

                }

                else

                {

                    CallMethod(dbSet, "Attach", new object[] { model });

                    db.Entry(model).State = EntityState.Modified;

                }

                if (model.GetType().IsSubclassOf(typeof(SH_SetBase)))

                {

                    ((SH_SetBase)model).LastUpdateTime = DateTime.Now;

                    ((SH_SetBase)model).IsDelete = false;

                }

                else

                {

                    ((SH_LogBase)model).LogTime = DateTime.Now;

                }

                db.SaveChanges();

                return true;

            }

        }

        public static bool Delete(SH_Base model)

        {

            using (ShopContext db = new ShopContext())

            {

                if (model.GetType().IsSubclassOf(typeof(SH_SetBase)))

                {

                    ((SH_SetBase)model).LastUpdateTime = DateTime.Now;

                    ((SH_SetBase)model).IsDelete = true;

                    db.Entry(model).State = EntityState.Modified;

                    db.SaveChanges();

                    return true;

                }

                object dbSet = GetDBSet(db, model);

                CallMethod(dbSet, "Remove", new object[] { model });

                db.Entry(model).State = EntityState.Modified;

                db.SaveChanges();

                return true;

            }

        }

        private static object GetDBSet(ShopContext db, SH_Base model)

        {

            string modelName = ObjectContext.GetObjectType(model.GetType()).Name;

            modelName = modelName.Replace("SH_", "");

            Type type = db.GetType();

            PropertyInfo property = type.GetProperty(modelName);

            object dbSet = property.GetValue(db);

            return dbSet;

        }

        private static object GetDBSet(ShopContext db, Type type)

        {

            type = ObjectContext.GetObjectType(type);

            string modelName = type.Name;

            modelName = modelName.Replace("SH_", "");

            PropertyInfo property = db.GetType().GetProperty(modelName);

            object dbSet = property.GetValue(db);

            return dbSet;

        }

        private static object CallMethod(object obj, string methodName, object[] parms)

        {

            Type type = obj.GetType();

            MethodInfo methodInfo = type.GetMethod(methodName);

            return methodInfo.Invoke(obj, parms);

        }

    }