具有linq搜索条件的C#泛型

Question

我正在尝试使用微小的辅助方法来简化日常操作但是在样本上:

public static int getEntityId<Type, Entity>(String name) where Entity: class
{
    Type type = _db.GetTable<Entity>().SingleOrDefault(t => t.name == name);
    return 0;
}

我收到错误:

Error 1 'Entity' does not contain a definition for 'name' and no extension method 'name' accepting a first argument of type 'Entity' could be found (are you missing a using directive or an assembly reference?) c:\work\asutp_migration\asutp_migration\Program.cs 89 62 asutp_migration

实际上,这是预期的错误,但如何解决这个问题呢？我将与此方法一起使用的所有表/类都具有"name"字段/属性.

UPD 1:根据建议,我这样做:

public partial class unit : IHasName
{
}

interface IHasName
{
    string name { get; }
    int id { get; }
}

public static int getEntityId<Type, Entity>(String name) where Entity: class, IHasName
{
    Type type = _db.GetTable<Entity>().SingleOrDefault(t => t.name == name);
    return (type == null) ? type.id : 0;
}

并使用代码:

int i = getEntityId<unit>("?");
Console.WriteLine(i);

我得到例外:

Unhandled Exception: System.NotSupportedException: The mapping of interface member IHasName.name is not supported.

UPD 2:http: //connect.microsoft.com/VisualStudio/feedback/details/344903/linq-to-sql-mapping-interface-member-not-supported-exception 我无法相信.它与我的问题有关吗？

UPD 3:是的,似乎是VS问题:http://social.msdn.microsoft.com/Forums/en/linqtosql/thread/bc2fbbce-eb63-4735-9b2d-26b4ab8fe589

UPD 4:

public static int getEntityId<Type>(String name) where Type: class, IHasName
{
    Type type = _db.GetTable<Type>().SingleOrDefault(t => t.name.Equals(name));
    return (type != null) ? type.id : 0;
}

所以这是一个解决方案,谢谢大家:-)

Answer 1

好吧,你需要制作一个通用约束来指定更具体的东西class.例如,如果您说where Entity : IHasName并IHasName定义了一个属性name,那么您将全部设置.