【阅读笔记】

EF里一共有5种状态(EntityState)：

游离Detached=1,

未变化Unchanged=2,

新增Added=4,

已删除Deleted=8,

已修改Modified=16

添加：前台暂不处理，通常按生成视图就可以

[HttpPost]        public ActionResult Create(Testmodel newtest)        {            try            {                // TODO: Add insert logic here                if (ModelState.IsValid)                {                    EntityState statebefore = db.Entry(newtest).State;  //Detached 实际无效，跟踪效果                    db.Testmodel.Add(newtest);                    EntityState stateAdd = db.Entry(newtest).State; //Added                    db.SaveChanges();                    EntityState stateafter = db.Entry(newtest).State;//Unchanged                    return RedirectToAction("Index");                }            }            catch            {                ModelState.AddModelError("", "错误提示.");                        }            return View(newtest);       }

编辑：

public ActionResult Edit(int id)        {            TestModel test= db.TestModel.Find(id);            return View(test);        }        [HttpPost]        public ActionResult Edit(TestModel model)        {                // TODO: Add update logic here                if (ModelState.IsValid)                {                    EntityState statebefore = db.Entry(model).State;                       db.Entry(model).State = EntityState.Modified;                    int i= db.SaveChanges();                    EntityState stateafter= db.Entry(model).State;                    return RedirectToAction("Index");                }            return View(model);        }

删除：

public ActionResult Delete(int id, bool? saveChangesError)        {            if (saveChangesError.GetValueOrDefault())            {                ViewBag.ErrorMessage = "错误提示.";            }            return View(db.Testmodel.Find(id));        }        //        // POST: /Student/Delete/5        [HttpPost,ActionName("Delete")]        public ActionResult DeleteConfirmed(int id)        {            try            {                // TODO: Add delete logic here                Testmodel model= db.Testmodel.Find(id);                EntityState statebefore = db.Entry(model).State; //UnChange                db.Testmodel.Remove(model);                EntityState stateafter = db.Entry(model).State;//Deleted                db.SaveChanges();                EntityState stateaOk = db.Entry(model).State;//Detached                return RedirectToAction("Index");            }            catch            {                return View();            }        }

　　

没了