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=,Birthday=new DateTime(,,) },
new Pet {Id=,Birthday=new DateTime(,,) },
new Pet {Id=,Birthday=new DateTime(,,) }
}; var query = pets.AsQueryable().WhereDateRange<Pet>(t => t.Birthday,DateTime.Now.AddYears(-), DateTime.Now.AddYears(-)); foreach(var item in query)
{
Console.WriteLine(item.Birthday.ToShortDateString());
}
}
} public class Pet
{
public int Id { get; set; }
public DateTime Birthday { get; set; }
}