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[ASP.net教程]C#根据日期范围过滤IQueryableT集合


 

需要扩展IQueryable<T>,参数包括一个DateTime类型的属性、开始日期、截止日期。

 

  public static class MyExtension  {    public static IQueryable<T> WhereDateRange<T>(this IQueryable<T> source, Expression<Func<T, DateTime>> getter, DateTime from, DateTime to)    {      Expression body = getter.Body;      var predicate = Expression.Lambda<Func<T, bool>>(        Expression.And(Expression.GreaterThanOrEqual(body, Expression.Constant(from)),Expression.LessThanOrEqual(body, Expression.Constant(to))),        getter.Parameters      );      return source.Where(predicate);    }  }

 

现在可以筛选满足某个日期范围内的集合。比如:

 

  class Program  {    static void Main(string[] args)    {      IEnumerable<Pet> pets = new List<Pet>      {        new Pet {Id=1,Birthday=new DateTime(2014,1,2) },        new Pet {Id=2,Birthday=new DateTime(2015,1,2) },        new Pet {Id=1,Birthday=new DateTime(2016,1,2) }      };      var query = pets.AsQueryable().WhereDateRange<Pet>(t => t.Birthday,DateTime.Now.AddYears(-2), DateTime.Now.AddYears(-1));      foreach(var item in query)      {        Console.WriteLine(item.Birthday.ToShortDateString());      }    }  }  public class Pet  {    public int Id { get; set; }    public DateTime Birthday { get; set; }  }