Boosting, Keyword Splitting

FetchSearchResults.cs

public SearchResults<CustomSearchResultItem>  SearchItemsByKeyword(string keyword)
{
	IQueryable<CustomSearchResultItem> query = context.GetQueryable<CustomSearchResultItem>();
	IQueryable<CustomSearchResultItem> query1 = context.GetQueryable<CustomSearchResultItem>();
	IQueryable<CustomSearchResultItem> query2 = context.GetQueryable<CustomSearchResultItem>();
	var expression = PredicateBuilder.True<CustomSearchResultItem>();
	var expression1 = PredicateBuilder.True<CustomSearchResultItem>();
	var expression2 = PredicateBuilder.True<CustomSearchResultItem>();
	// Applying normal boosting to all the fields
	var namePredicate = PredicateBuilder.False<CustomSearchResultItem>();
	namePredicate = namePredicate.Or(w => w.Title.Equals(keyword).Boost(5f));
	namePredicate = namePredicate.Or(w => w.Description.Equals(keyword).Boost(3f));
	namePredicate = namePredicate.Or(w => w.Category.Equals(keyword).Boost(2f));
	namePredicate = namePredicate.Or(w => w.Content.Contains(keyword));
	// For splitting the keywords
	var splitwords = keyword.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
	var splitnamePredicate = PredicateBuilder.True<CustomSearchResultItem>();
	foreach (string term in splitwords)
	{
		splitnamePredicate = splitnamePredicate1.And(p => p.Title.Contains(term.Trim()).Boost(4f));
	}
	namePredicate = namePredicate.Or(splitnamePredicate);
	// For Permuted splitted words
	var permutedSplitnamePredicate = PredicateBuilder.True<CustomSearchResultItem>();	
	var permutedSplitwords = findWords(splitwords);
	int count = 0;
	foreach (string term in permutedSplitwords)
	{
		float value = (float)(4 - (0.002 * count));
		permutedSplitnamePredicate = permutedSplitnamePredicate.Or(p => p.Title.Contains(term.Trim()).Boost(value));
		count++;
	}
	namePredicate = namePredicate.Or(permutedSplitnamePredicate);
	// Final expression with all the predicates
	expression = expression.And(namePredicate);
	// Final query for performing the union of results
	var statusActivePredicate = PredicateBuilder.False<CustomSearchResultItem>();
	statusActivePredicate = statusActivePredicate.Or(w => w.status.Equals("active", StringComparison.InvariantCultureIgnoreCase));
	expression1 = expression.And(statusActivePredicate);
	query1 = query.Where(expression1);
	var results1 = query1.GetResults();

	var statusDiscontinuedPredicate = PredicateBuilder.False<CustomSearchResultItem>();
	statusDiscontinuedPredicate = statusDiscontinuedPredicate.Or(w => w.status.Equals("discontinued", StringComparison.InvariantCultureIgnoreCase));
	expression2 = expression.And(statusDiscontinuedPredicate);
	query2 = query.Where(expression2);
	var results2 = query2.GetResults();

	var unionResults = results1.Union(results2);
	SearchResults<CustomSearchResultItem> finalResults = new SearchResults<CustomSearchResultItem>(unionResults, unionResults.Count());
	return finalResults;
}

public static String[] findWords(params string[] args)
{

	if (args.Count() == 0)
	{
		return new String[] { "" };
	}
	else
	{
		String[] oldWords = findWords(args.Skip(1).ToArray());
		String[] newWords = oldWords.Where(word => word == "" || word.Split(new String[] { " " }, StringSplitOptions.RemoveEmptyEntries)[0] == args[1])
									.Select(word => (args[0] + " " + word).Trim()).ToArray();

		return oldWords.Union(newWords).ToArray();
	}
}