Boost Solr query and prioritize exact match

Question

I have few records in Solr index.

1. Bachelor of Nursing
2. Bachelor of Nursing (Honours)

My requirement is that when I want to search Bachelor of Nursing then Bachelor of Nursing should display first and then Bachelor of Nursing (Honours) because Bachelor of Nursing have the exact match.

I have created below query for Solr

(((name_t_en:"Bachelor of Nursing")^3.0
OR (name_t_en:"*Bachelor*")^2.5 OR (name_t_en:"*Nursing*")^2.5 OR (keywords_t_en:"*Bachelor*")^2.0 OR (keywords_t_en:"*Nursing*")^2.0)  
)

but I am not getting result in proper way which I want.

While I am getting results, I am using below code in Visual Studio:

var namePredicate = PredicateBuilder.True<ContentPageSearchModel>();
var contentPredicate = PredicateBuilder.True<ContentPageSearchModel>();
var NamePredicate = PredicateBuilder.True<ContentPageSearchModel>();
var ExactNamePredicate = PredicateBuilder.True<ContentPageSearchModel>();
ExactNamePredicate = ExactNamePredicate.Or(item => item.Name == text).Boost(3.0f);
foreach (var word in terms)
{
    NamePredicate = NamePredicate.And(item => item.Name.Contains(word).Boost(2.5f));
    contentPredicate = contentPredicate.Or(item => item.Keywords.Contains(word).Boost(2.0f));
}
namePredicate = ExactNamePredicate.Or(NamePredicate).Or(contentPredicate);

Answer 1

Something like this has worked for me. Beyond the boosting, the important part is to have the exact match Or the loose match. exactPredicate.Or(loosePredicate); That will build the proper SOLR query.

{
    var parentPredicate = PredicateBuilder.True<ContentPageSearchModel>();
    var exactPredicate = PredicateBuilder.False<ContentPageSearchModel>();
    var loosePredicate = PredicateBuilder.False<ContentPageSearchModel>();


    exactPredicates = exactPredicates.Or(i => i.Title.Contains(query)).Boost(40); 

    // you can use the wildcard search or Contains. 
    foreach (var word in query.QueryText.Split(' '))
    {
        if (word.Length > 2)
            loosePredicate = loosePredicate.Or(i => i.Title.MatchWildcard("*" + word + "*").Boost(-100f));
    }

    // don't use both of these
    foreach (var word in query.QueryText.Split(' '))
    {
        if (word.Length > 2)
            loosePredicate = loosePredicate.Or(i => i.Title.Contains(word));
    }

    parentPredicate = exactPredicate.Or(loosePredicate);

}

Answer 2

I have implemented the same functionality with the following code in sitecore 9 update 2

 if (sortBy !="date")
            {
                string termFreq = GetTermFrequency("suggestiontitle_t", searchText);
                var query = context.GetQueryable<SearchResultModel>()
                     .Where(i => i.NoIndex == false && (i.PageTitle.Contains(searchText).Boost(5.0f) || i.SearchDescription.Contains(searchText).Boost(4.0f) || i.KeyWords.Contains(searchText).Boost(3.0f) || i.SContent.Contains(searchText).Boost(2.0f))).OrderByDescending(q =>q[termFreq]);
                totalCount = query.Count();
                Results = query?.Skip((page - 1) * count).Take(count).ToList();
            }

 private static string GetTermFrequency(string fieldName, string searchText)
    {
        return string.Format("termfreq({0},'{1}')", fieldName, searchText);
    }

Answer 3

I have this working through the below code. Basically I'm doing the following:

1. Splitting the search term into words and getting the entire length
2. Building one predicate for entire search term together and doing a boost by (length * length)
3. Building predicates for each of the word and then doing an Or with the above predicate

var tokens = request.SearchTerm.Split(' ');
var length = tokens.Length;

float allWordsBoost = (float)length * length;
predicate = predicate.And(item => item.SearchTerms.Contains(request.SearchTerm).Boost(allWordsBoost));

var termsPredicate = PredicateBuilder.True<ContentPageSearchModel>();

var eachTermPredicate = PredicateBuilder.True<ContentPageSearchModel>();


for (int i = 0; i < length; i++)
{
   float b = (float)length - i;
   var word = tokens[i];
   eachTermPredicate = eachTermPredicate.Or(Item => 
        Item.SearchTerms.Contains(word).Boost(b));
}

termsPredicate = termsPredicate.And(eachTermPredicate);

predicate = predicate.Or(termsPredicate);