▼  Models/Data.cs

using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace DotNetNote.Models
{
  public class Data
  {
      public int Id { get; set; }
      public string Name { get; set; }
      public string Title { get; set; }
  }
  
  public class DataService
  {
      private readonly List<Data> _data = new List<Data>()
      {
          new Data { Id = 1, Name = “김태영”, Title = “안녕하세요.” },
          new Data { Id = 2, Name = “박용준”, Title = “반갑습니다.” },
          new Data { Id = 3, Name = “한상훈”, Title = “또 만나요.” },
      };
      
      public List<Data> GetAll()
      {
          return _data;
      }
      
      public Data GetDataById(int id)
      {
          return _data.Where(n => n.Id == id).SingleOrDefault();
      }
      
      public List<Data> GetDataByName(string name)
      {
          return _data.Where(
              n => n.Name.ToLower().Equals(name.ToLower())).ToList();
      }
  }
  
  public class DataFinder
  {
      private DataService _service = new DataService();
      
      public async Task<Data> GetDataById(int id)
      {
          return await Task.FromResult(_service.GetDataById(id));
      }
  }
}

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