Question

这是一个棘手的问题：我想对Lucene搜索结果进行延迟加载。可能？

这是我的代码：

public IEnumerable<BizObj> Search(string query)
{
   var parsedQuery = new QueryParser(...).Parse();
   var searcher = new IndexSearcher(parsedQuery, storage);
   try
   {
      var hits = searcher.Search(parsedQuery);

      // Hooray for LINQ's lazy-evaluated Select method!
      // But oh noes!! searcher will be closed by the time it
      // gets executed, thus resulting in an exception. :-(
      return hits.Select(hit => PullBizObjectFromDatabase(hit));
   }
   finally
   {
      searcher.Close();
   }
}

消耗代码：

var searchResults = from result in blah.Search("hello, world!")
                    where SomeBizLogic(result)
                    select result;

// Print the top 50 search results.
foreach (var result in searchResults.Take(50))
{
    // Exception! The searcher field inside Search(...) has been closed! :-(
    Console.WriteLine(result);
}

我的问题是，我如何延迟加载Lucene的搜索结果？

Answer 1

在玩了几个选项之后，我找到了答案：使用yield return iterator：

public IEnumerable<BizObj> Search(string query)
{
   var parsedQuery = new QueryParser(...).Parse();
   var searcher = new IndexSearcher(parsedQuery, storage);
   try
   {
      var hits = searcher.Search(parsedQuery);
      foreach (var hit in hits)
      {
         yield return PullBizObjectFromDatabase(hit);
      }
   }
   finally
   {
      searcher.Close();
   }
}

使用yield return iterator，搜索者在消费者完成评估之前不会被处理。辉煌！来自Lucene的延迟加载搜索结果，正是我所寻找的。嗬！： - ）

Answer 2

查看HitCollector对象。例如。 http://rosowski.wordpress.com/2008/07/29/lucene-using-the-hitcollector/

Lucene.NET和延迟加载

2 个答案: