BaseWriter.cs

using System.Collections.Generic;
using System.Linq;
using log4net;
using Lucene.Net.Analysis.Standard;
using Lucene.Net.Index;
using Lucene.Net.Search;
using Lucene.Net.Util;

namespace LuceneWrapper
{
    /// <summary>
    /// Base abstract class that every Writer should implement
    /// </summary>
    public abstract class BaseWriter : BaseSearch
    {
        private static readonly ILog Log = LogManager.GetLogger(typeof(BaseWriter));

        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="dataFolder"></param>
        protected BaseWriter(string dataFolder):base(dataFolder)
        {
            Log.DebugFormat("Initialisation Writer with folder {0}", dataFolder);
        }

        /// <summary>
        /// Private helper to add an item to the Index
        /// </summary>
        /// <param name="doc">A ADocument type, representing the values that have to be added to the index</param>
        /// <param name="writer">The Lucene writer</param>
        private void AddItemToIndex(ADocument doc, IndexWriter writer)
        {
            Log.DebugFormat("Adding document to index: Type {0}");
            var query = new TermQuery(new Term("Id", doc.Id.ToString()));
            writer.DeleteDocuments(query);
            writer.AddDocument(doc.Document);
        }

        /// <summary>
        /// Adds or update items in the Lucene index
        /// </summary>
        /// <param name="docs">The documents that have to be updated or added in the database</param>
        protected void AddUpdateItemsToIndex(IEnumerable<ADocument> docs)
        {
            Log.DebugFormat("Adding {0} items to index",docs.Count());
            var standardAnalyzer = new StandardAnalyzer(Version.LUCENE_30);

            using (var writer = new IndexWriter(LuceneDirectory, standardAnalyzer, IndexWriter.MaxFieldLength.UNLIMITED))
            {
                foreach (var doc in docs)
                {
                    Log.DebugFormat("Adding item to index: {0}: ",doc);
                    AddItemToIndex(doc, writer);
                }
                standardAnalyzer.Close();
                writer.Dispose();
            }
        }

        /// <summary>
        /// Private helper to delete an item from the index
        /// </summary>
        /// <param name="doc">The document representing the item that has to be deleted</param>
        /// <param name="writer">The Lucene writer</param>
        private void DeleteItemFromIndex(ADocument doc, IndexWriter writer)
        {
            Log.DebugFormat("Deleting item {0} from index",doc);
            var query = new TermQuery(new Term("Id", doc.Id.ToString()));
            writer.DeleteDocuments(query);
        }

        /// <summary>
        /// Deletes ites from the Lucene index
        /// </summary>
        /// <param name="docs"></param>
        protected void DeleteItemsFromIndex(IEnumerable<ADocument> docs)
        {
            Log.DebugFormat("Deleting {0} items from index",docs.Count());
            var standardAnalyzer = new StandardAnalyzer(Version.LUCENE_30);

            using (var writer = new IndexWriter(LuceneDirectory, standardAnalyzer, IndexWriter.MaxFieldLength.UNLIMITED))
            {
                foreach (var doc in docs)
                {
                    Log.DebugFormat("Deleting item from index: {0}",doc);
                    DeleteItemFromIndex(doc, writer);
                }
                standardAnalyzer.Close();
                writer.Dispose();
            }
        }

        /// <summary>
        /// optimizes the Lucene Index
        /// </summary>
        protected void Optimize()
        {
            Log.Debug("optimizing Lucene search index");
            var standardAnalyzer = new StandardAnalyzer(Version.LUCENE_30);

            using (var writer = new IndexWriter(LuceneDirectory, standardAnalyzer, IndexWriter.MaxFieldLength.UNLIMITED))
            {
                standardAnalyzer.Close();
                writer.Optimize();
                writer.Dispose();
            }
        }
    }
}