c# - 创建通用 LINQ 函数以返回传入的类型

Question

两个 LINQ 方法做同样的事情但是接受和返回不同的类型

private IQueryable<Type1>FilterBySomething(IQueryable<Type1> results)
{
    if (ThisField!= null)
    {
        results = results.Where(x => x.Thisfield == ThisField.Value);
    }
    return results;
}

private IQueryable<Type2>FilterBySomething(IQueryable<Type2> results)
{
    if (ThisField!= null)
    {
        results = results.Where(x => x.Thisfield == ThisField.Value);
    }
    return results;
}

问题在于重复。我想要一个执行此操作的通用函数，但我不知道该怎么做

Answer 1

1. 引入新界面:

   interface IThisfieldSupported
   {
       string Thisfield {get;set;}
   }
   

2. 设置限制:

   private IQueryable<Type1> FilterBySomething<Type1>(IQueryable<Type1> results) where Type1 : class, IThisfieldSupported
   {
       if (ThisField!= null)
       {
           results = results.Where(x => x.Thisfield == ThisField.Value);
       }
       return results;
   }
   

3. 用不同的类调用它，但在这个类中实现 IThisfieldSupported:

   class Data : IThisfieldSupported
   {
       string Thisfield { get;set; }
       int Id { get;set; }
   }
   ...
   var data = new Data[10];
   var result = FilterBySomething(data);