如何在Linqtosql中生成通用的GetById（int Id）函數？

Question

我想通過使用相同的功能來獲取實體。

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(); 
} 

如何編寫有效函數？有任何想法嗎 ？

Answer 1

您可以創建一個接口來聲明Id屬性並在您的實體中實現它。然後你就可以添加一個約束是這樣的：

// 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(); 

}