Lucene to relational mapping for .NET

Question

Is there a Lucene (Lucene.NET) to relational database mapping framework recommended for .NET?

I wanted to use Lucene for search purpose off-loading all search from my relational database.

Answer 1

There are some open source project like SimpleLucene but I haven't used any one of them.

As you said you can think of lucene as a single DB table ( i thought of, in lucene we have document that we can theoretically treat it as a single relational table ). So I don't think that you will need a complex relational database mapping framework for a single table. Some extension methods like below can make you start to play with Lucene.Net.

public static class LuceneExtension
{
    public static void Index(this IndexWriter writer, object obj)
    {
        Document doc = new Document();

        obj.GetType()
           .GetProperties()
           .Select(p => new { Name = p.Name, Value = p.GetValue(obj, null) })
           .ToList()
           .ForEach(f=>doc.Add( new Field(f.Name,f.Value.ToString(),Field.Store.YES,Field.Index.ANALYZED) ));

        writer.AddDocument(doc);

    }
}

---

For example

indexWriter.Index(new { text = "some text to index" , id = "555" });

would index a document with fields text and id

Answer 2

You could also check Lucene2Objects hosted in Nuget and with sample introduction article in my blog . Basically allows you to abstract from Lucene and think on objects, you could even annotate your domain entities, like this:

[SearchableEntity(DefaultSearchProperty = "Text")]
public class Message
{
 public int Id { get; set; }

 [Indexed]
 public string Text { get; set; }

 [Indexed]
 public string Title { get; set; }

 public DateTime Sent { get; set; }

 public DateTime? Read { get; set; }
}

And then, save like this:

var iWriter = new IndexWriter(Environment.CurrentDirectory + @"\index");
var message = new Message { Id = 12, Sent = DateTime.Now, 
                            Text = "Some text on the message!", 
                            Title = "This is the title" 
              };
iWriter.AddEntity(message);
iWriter.Close();

And search your index like this

var iReader = new IndexReader(Environment.CurrentDirectory + @"\index");
var messages = iReader.Search<Message>("text");

foreach (var message in messages) {
 Console.WriteLine("Message: {0}", message.Title);
}

Sorry if the answer is too long. Hope I can help!

DISCLAIMER: As you may have imagined, I wrote the library.