Question

我正在MVC使用Entity Framework应用

我必须更新一个唯一字段，在1中自动增加此值。

＆＃13;

  ConnectionEntities _db;
 
 public void AddingVisits(long upload_id)
        {
            var upload = new Uploads() { Upload_id = upload_id, CantVisits = CantVisits + 1 };
            _db.Uploads.Attach(upload);
            _db.Entry(upload).Property(x => x.CantVisits).IsModified = true;
            _db.Configuration.ValidateOnSaveEnabled = false;
            _db.SaveChanges();
        }

＆＃13;

上传是Entity，Upload_id是缩进字段，我需要增加CantVisits字段，将1加到当前值。

这个例子让我在行

中出错

CantVisits = CantVisits

我不知道这个当前值是什么，我想避免使用select来获取此值。

这是可能的吗？

Answer 1

如果该列不是标识，并且您只想向该属性添加一个，则可以执行此操作：

var upload = new Uploads() { Upload_id = upload_id };
//Attach the existing entity to the context
_db.Uploads.Attach(upload);
// due to you set a property, the EF change tracker will detect your entity was modified, if you haven't disabled it
upload.CantVisits+=1;
_db.SaveChanges();

或将实体状态更改为Modified：

var upload = new Uploads() { Upload_id = upload_id };
// due to you set a property the entity change tracker will detect your entity was modified, if you haven't disabled it
upload.CantVisits+=1;
context.Entry(upload).State = EntityState.Modified; 

_db.SaveChanges();

mvc实体框架更新字段递增此值

1 个答案: