Sitecore Search Predicate Builder multiple keyword search with boosting not working as desired

Question

I have sitecore pages / lucene documents with the following fields:

Title
Filename
Content
File Contents

I'm creating a search for these and have the following requirements:

Hits containing the whole phrase in the title field should be returned first.
Hits containing the whole phrase in the filename field should be returned second.
Hits containing the whole phrase in the content should be returned third
Hits containing the whole phrase in the file contents should be returned fourth
Hits containing all of the keywords (in any order) in the title field should be returned fifth
Hits containing all of the keywords (in any order) in the filename field should be returned sixth
Hits containing all of the keywords (in any order) in the content should be returned seventh.
Hits containing all of the keywords (in any order) in the file contents should be returned eighth.

Here is what I've got:

    public static Expression<Func<T, bool>> GetSearchTermPredicate<T>(string searchTerm) 
        where T : ISearchableItem
    {
        var actualPhrasePredicate = PredicateBuilder.True<T>()
            .Or(r => r.Title.Contains(searchTerm).Boost(2f))
            .Or(r => r.FileName.Contains(searchTerm).Boost(1.5f))
            .Or(r => r.Content.Contains(searchTerm))
            .Or(r => r.DocumentContents.Contains(searchTerm));

        var individualWordsPredicate = PredicateBuilder.False<T>();

        foreach (var term in searchTerm.Split(' '))
        {
            individualWordsPredicate 
                = individualWordsPredicate.And(r => 
                   r.Title.Contains(term).Boost(2f)
                || r.FileName.Contains(term).Boost(1.5f)
                || r.Content.Contains(term)
                || r.DocumentContents.Contains(term));
        }

        return PredicateBuilder.Or(actualPhrasePredicate.Boost(2f), 
            individualWordsPredicate);
    }

The actual phrase part seems to work well. Hits with the full phrase in the title are returned first. However, if I remove a word from the middle of the phrase, no results are returned.

i.e. I have a page with a title "The England football team are dreadful", but when I search with "The football team are dreadful", it doesn't find the page.

Note: pages can have documents attached to them, so I want to boost the filenames too but not as highly as the page title.

David Masters David Masters · Accepted Answer · 2016-07-08T13:59:18

I managed to get this to work with the following:

    public static Expression<Func<T, bool>> GetSearchTermPredicate<T>(string searchTerm) 
        where T : ISearchableItem
    {
        var actualPhraseInTitlePredicate = PredicateBuilder.True<T>()
            .And(r => r.Title.Contains(searchTerm));

        var actualPhraseInFileNamePredicate = PredicateBuilder.True<T>()
            .And(r => r.FileName.Contains(searchTerm));

        var actualPhraseInContentPredicate = PredicateBuilder.True<T>()
            .And(r => r.Content.Contains(searchTerm));

        var actualPhraseInDocumentPredicate = PredicateBuilder.True<T>()
            .And(r => r.DocumentContents.Contains(searchTerm));

        var terms = searchTerm.Split(' ');

        var titleContainsAllTermsPredicate = PredicateBuilder.True<T>();

        foreach (var term in terms)
            titleContainsAllTermsPredicate 
                = titleContainsAllTermsPredicate.And(r => r.Title.Contains(term).Boost(2f));

        var fileNameAllTermsContains = PredicateBuilder.True<T>();

        foreach (var term in terms)
            fileNameAllTermsContains 
                = fileNameAllTermsContains.And(r => r.FileName.Contains(term));

        var contentContainsAllTermsPredicate = PredicateBuilder.True<T>();

        foreach (var term in terms)
            contentContainsAllTermsPredicate 
                = contentContainsAllTermsPredicate.And(r => r.Content.Contains(term));

        var documentContainsAllTermsPredicate = PredicateBuilder.True<T>();

        foreach (var term in terms)
            documentContainsAllTermsPredicate 
                = documentContainsAllTermsPredicate.And(r => r.DocumentContents.Contains(term));


        var predicate = actualPhraseInTitlePredicate.Boost(3f)
            .Or(actualPhraseInFileNamePredicate.Boost(2.5f))
            .Or(actualPhraseInContentPredicate.Boost(2f))
            .Or(actualPhraseInDocumentPredicate.Boost(1.5f))
            .Or(titleContainsAllTermsPredicate.Boost(1.2f))
            .Or(fileNameAllTermsContains.Boost(1.2f))
            .Or(contentContainsAllTermsPredicate)
            .Or(documentContainsAllTermsPredicate);

        return predicate;
    }

It's obviously quite a bit more code, but I think separating the predicates makes more sense for boosting to work effectively.

The main issue with the previous code was two fold:

PredicateBuilder.Or(actualPhrasePredicate.Boost(2f), individualWordsPredicate) doesn't seem to include the predicate being Or'd. When doing a .ToString() on the resulting joined predicate, the expression didn't contain anything for the individualWordsPredicate
After fixing that it still didn't work, and this was because I was using PredicateBuilder.False<T>() for the individualWordsPredicate. When looking at the expression it was basically producing (False AND Field.Contains(keyword)) which of course will never evaluate to true. Using .True<T>() fixed this.

Sitecore Search Predicate Builder multiple keyword search with boosting not working as desired

1 Answers