MVC ---- EF高级增删改

//高级修改（创建对象）
public void EditAdance(){
    //创建要修改的对象
    Parameter pm = new Parameter()
    {
        ParaNo = "00001",
        ParaName = "会员卡补偿" //修改参数名称
    };
    //通过上下文获取对象相关信息
    //Entry获取给定实体的对象
    DbEntityEntry<Parameter> entry = dbNe.Entry<Parameter>(pm);
    //对象的状态是没有修改
    entry.State =　System.Data.Entity.EntityState.Unchanged;
    //对象的属性值ParaName修改了
    entry.Property("ParaName").IsModified = true;
    //会只能判断哪个对象的那个属性值修改了
    dbNe.SaveChanges();
    
}

//高级删除
public void DeleAdvance()
{
    //先查后删除
    Parameter pDe =new Parameter()
    {
        paraNo = "00002"
    }    
    //通过上下文获取对象的相关信息
    DbEntityEntry<Parameter> entry =dbNe.Entity<Parameter>(pDe);
    //对象的状态是删除
    entry.State = System.Data.EntityState.Deleted;
    //智能判断对象的状态
    dbNe.SaveChanges();
}
 

 //高级参数新增
 public void AddAdvance()
 {
     //参数对象
     Parameter parm = new Parameter(){
        ParaNo = "00003",
        ParaName = "预交金初始值",        
        ParaValue = "100",
        ParaRemark = ""
     };
     DbEntityEntry<Parameter> entry = dbNe.Entry<Parameter>(parm);
     entry.State = System.Data.EntityState.Added;
     dbNe.SaveChanges();//保存至数据库
 }
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 第二次总结方法   

  
//修改
public IActionResult Update(int Id) 
        {
            UserTable ut = dbContext.Set<UserTable>().Find(Id);
            ut.Name = "武器大师";
             
            //旧写法
            //var entry = dbContext.Set<UserTable>().Attach(ut);
            //dbContext.Entry(ut).State = EntityState.Modified;
            //dbContext.SaveChanges();

            //新写法
            dbContext.Set<UserTable>().Update(ut);
            dbContext.SaveChanges();

            return RedirectToAction("Index");
        }

//删除  
public IActionResult Del(string Id)
        {
            UserTable ut = dbContext.Set<UserTable>().Find(Id);
            dbContext.Set<UserTable>().Remove(ut);
            dbContext.SaveChanges();
            return RedirectToAction("Index");
        }

 

public class EFDao<T> : IDao<T> where T : class
    {
        private EnergyIotDbContext db;
 
        public EFDao(EnergyIotDbContext _db)
        {
            db = _db;
        }
 
        public async Task<bool> Add(T Entity)
        {
 
            //老写法
            //db.Entry(Entity).State = EntityState.Added;
            await db.Set<T>().AddAsync(Entity);
            return await db.SaveChangesAsync() > 0;
        }
 
        public async Task<bool> Delete(T Entity)
        {
            //老写法
            //db.Set<T>().Attach(Entity);
            //db.Entry(Entity).State = EntityState.Deleted;
            //新写法
            db.Set<T>().Remove(Entity);
            return await db.SaveChangesAsync() > 0;
        }
 
        public async Task<bool> Update(T Entity)
        {
            //老写法
            //db.Set<T>().Attach(Entity);
            //db.Entry(Entity).State = EntityState.Modified;
            //新写法
            db.Set<T>().Update(Entity);
            return await db.SaveChangesAsync() > 0;
        }
 
        public IEnumerable<T> GetEntities(Expression<Func<T, bool>> exp)
        {
            //var data = db.Set<T>().Find()
            return CompileQuery(exp);
        }
 
        public IEnumerable<T> GetEntitiesForPaging(int Page, int pageSize, Expression<Func<T, bool>> exp)
        {
            return CompileQuery(exp).Skip((Page - 1) * pageSize).Take(pageSize);
        }
 
        public T GetEntity(Expression<Func<T, bool>> exp)
        {
            return CompileQuerySingle(exp);
        }
 
        private IEnumerable<T> CompileQuery(Expression<Func<T, bool>> exp)
        {
            var func = EF.CompileQuery((EnergyIotDbContext context, Expression<Func<T, bool>> exps) => context.Set<T>().Where(exp));
            return func(db, exp);
        }
        private T CompileQuerySingle(Expression<Func<T, bool>> exp)
        {
            var func = EF.CompileQuery((EnergyIotDbContext context, Expression<Func<T, bool>> exps) => context.Set<T>().FirstOrDefault(exp));
            return func(db, exp);
        }
    }