Power of Dynamics

Program.cs

using System;
using System.Collections.Generic;
using System.Dynamic;

namespace Demo
{

  class Program
  {
    static void Main()
    {
      var dataStore = new DataStore();
      dataStore.Add(new Artist("Mozart", "Classical"));
      dataStore.Add(new Artist("Bach", "Classical"));
      dataStore.Add(new Song("Air"));
      
      // case 1 : find category property with value classical 
      dynamic dataFinder = new SmartDataFinder(dataStore);
      var matchingClassicals = dataFinder.FindByCategory("Classical");
      PrintNames(matchingClassicals);
     
      // case 2: find name property with value air 
      var matchingNames = dataFinder.FindByName("Air");
      PrintNames(matchingNames);
    }

    private static void PrintNames(IEnumerable<dynamic> foundItems)
    {
      foreach (var item in foundItems)
      {
        Console.WriteLine(item.Name);
      }
    }
  }

  public class SmartDataFinder : DynamicObject
  {
    const string FindByMethodMatch = "FindBy";
    readonly DataStore _dataStore;

    public SmartDataFinder(DataStore dataStore)
    {
      _dataStore = dataStore;
    }
    
    public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result)
    {
      if (binder.Name.StartsWith(FindByMethodMatch))
      {
        var matchingPropertyName = binder.Name.Substring(FindByMethodMatch.Length);
        var value = args[0].ToString();

        // find items with matching property and value 
        var matchingItems = new List<object>();
        foreach (var item in _dataStore.Items)
        {
          var properties = item.GetType().GetProperties();
          foreach(var propertyInfo in properties)
          {
            if (!propertyInfo.Name.Contains(matchingPropertyName)) continue;
            var propertyVal = propertyInfo.GetValue(item, null);
            if (!(propertyVal is string) || (string) propertyVal != value) continue;
            matchingItems.Add(item);
            break;
          }
        }
        result = matchingItems;
        return true;
      }
      return base.TryInvokeMember(binder, args, out result);
    }
  }

  public class DataStore
  {
    readonly IList<dynamic> _items;

    public IEnumerable<dynamic> Items { get { return _items; } } 

    public DataStore()
    {
      _items = new List<dynamic>();
    }

    public void Add<T>(T item)
    {
      _items.Add(item);
    }
  }

  public class Song
  {
    public string Name { get; private set; }

    public Song(string name)
    {
      Name = name;
    }
  }
  public class Artist
  {
    public string Name { get; private set; }
    public string Category { get; private set; }

    public Artist(string name, string category)
    {
      Category = category;
      Name = name;
    }
  }
}