public class GetAllTasksInput : PagedAndSortedResultRequestDto

{

    public TaskState? State { get; set; }

}

public class TaskAppService : AsyncCrudAppService<Task, TaskDto, int, GetAllTasksInput>

{

    public TaskAppService(IRepository<Task> repository)

        : base(repository)

    {

    }

    protected override IQueryable<Task> CreateFilteredQuery(GetAllTasksInput input)

    {

        return base.CreateFilteredQuery(input)

            .WhereIf(input.State.HasValue, t => t.State == input.State.Value);

    }

}

分页：

http://www.cnblogs.com/sheng-jie/p/6337426.html

https://github.com/dncuug/X.PagedList

参考：

https://aspnetboilerplate.com/Pages/Documents/Application-Services

https://docs.microsoft.com/en-us/aspnet/core/data/ef-rp/sort-filter-page?view=aspnetcore-2.2