如何在Linqtosql中生成通用的GetById（int Id）函数？

Question

我想通过使用相同的功能来获取实体。

public static T getById<T>(int Id) 
{ 
     myDataContect db = new myDataContect(); 
     return (from u in db.GetTable<T> where u.Id == Id select u).FirstOrDefault(); 
} 

如何编写有效函数？有任何想法吗 ？

Answer 1

您可以创建一个接口来声明Id属性并在您的实体中实现它。然后你就可以添加一个约束是这样的：

// you can figure out a better name this just for example 
public interface ICommon 
{ 
    int Id { get; set; } 
} 

public static T getById<T>(int Id) where T : class, ICommon 
{ 
    myDataContect db = new myDataContect(); 
    return (from u in db.GetTable<T> where u.Id == Id select u).FirstOrDefault(); 
} 

Answer 2

public interface ID 
{ 
    int Id { get; } 
} 

public class IDImpl : ID 
{ 
    public int Id { get; private set; } 
} 

public static T GetById<T>(int id) where T : ID 
{ 
    var myDataContect db = new myDataContect(); 
    return (from u in db.GetTable<T> where u.Id == id select u).FirstOrDefault(); 

}