“访问非静态字段需要对象引用”

Question

我的 WCF 服务实现中有此代码，但我收到此错误 ：

 'an object reference is required to access non-static field, method or property    
   System.Data.Linq.DataContext.User.get

如何正确更新用户的位置？代码如下：

public  void UpdateLocation(string usrName, double usrLong, double usrLat)
        {

            var result = (from usr in DataClasses1DataContext.Users
                          where usr.usrName == usrName
                          select usr).Single();
            result.usrLong = usrLong;
            result.usrLat = usrLat;
            DataClasses1DataContext.SubmitChanges();}

Answer 1

错误消息告诉您所有您需要知道的信息，Users 属性不是静态的，但您按原样调用它。您需要一个 DataClasses1DataContext 的实例来调用该属性：

using(DataClasses1DataContext context = new DataClasses1DataContext())
{
   var result = (from usr in context.Users
                          where usr.usrName == usrName
                          select usr).Single();
}

Answer 2

正如伊恩所说，

public  void UpdateLocation(string usrName, double usrLong, double usrLat)
{
    using(DataClasses1DataContext Usercontext = new DataClasses1DataContext())
    {
        var result = (from usr in Usercontext.Users where usr.usrName == usrName select usr).Single();

        result.usrLong = usrLong;
        result.usrLat = usrLat;

        Usercontext.SubmitChanges();
   }
}