如何在c#中通过反射更新数据库

Question

我想通过反射更新一个表实例

这是我尝试过的

var type = Assembly.GetExecutingAssembly().GetTypes()
    .FirstOrDefault(t => t.Name == TableName);


object instance = Activator.CreateInstance(type);

foreach (var item in dic)
{

    PropertyInfo information = type.GetProperties()
        .SingleOrDefault(x => x.Name == item.Key);

    information.SetValue(instance, item.Value.ToString(), null);

}
var fx = db.Set(instance.GetType());
fx.Add(instance);
result= db.SaveChanges();

它给了我以下异常

   InnerException = {"Violation of PRIMARY KEY constraint
 'PK_primryKeyName. Cannot insert duplicate key in object 'tableName'.
 The duplicate key value is (39).
\r\nThe statement has been terminated."}

它似乎实体框架将其视为插入而不是更新

Answer 1

这就是我们在不返回并通过手动选择获取的情况下处理未附加的事物的方式。

   var type = Assembly.GetExecutingAssembly().GetTypes()
   .FirstOrDefault(t => t.Name == "");


            object instance = Activator.CreateInstance(type);

            foreach (var item in new Dictionary<string, string>())
            {

                PropertyInfo information = type.GetProperties()
    .SingleOrDefault(x => x.Name == item.Key);

                information.SetValue(instance, item.Value.ToString(), null);

            }               

            db.Entry(instance).State = EntityState.Modified;
            db.SaveChanges();