Facet Search Code

Build Predicate

public static Expression<Func<SearchModel, bool>> GetSearchPredicate(string searchTerm, string type)
{
    var predicate = PredicateBuilder.True<SearchModel>(); // Items which meet the predicate
            
    // Search the whole phrase - LIKE
    predicate = predicate.Or(x => x.DispalyName.Like(searchTerm)).Boost(1.2f);
    predicate = predicate.Or(x => x.PageDescription.Like(searchTerm)).Boost(1.2f);

    // Search the whole phrase - CONTAINS
    predicate = predicate.Or(x => x.DispalyName.Contains(searchTerm)).Boost(2.0f);
    predicate = predicate.Or(x => x.PageDescription.Contains(searchTerm)).Boost(2.0f);

    // Search the individual words
    foreach (var t in searchTerm.Split(' '))
    {
        var tempTerm = t;

        predicate = predicate.Or(x => x.DispalyName.Contains(t)).Boost(20);
        predicate = predicate.Or(x => x.PageDescription.Contains(t)).Boost(20);
    }

    // Only show items which are not excluded from search
    predicate = predicate.And(x => x.ExcludeFromSearch == false);

    // Type filtering
    predicate = predicate.And(GetFacetPredicate(type));

    return predicate;
}

public static Expression<Func<SearchModel, bool>> GetFacetPredicate(string type)
{
    var predicate = PredicateBuilder.True<SearchModel>(); // Items which meet the predicate

    if (type != null)
    {
        predicate = predicate.Or(x => x.Type == type);
    }

    return predicate;
}

Model

/// <summary>
/// Search item mapped to Lucene index
/// </summary>
public class SearchModel
{
    [IndexField("_name")]
    public string ItemName { get; set; }

    [IndexField("_displayname")]
    public string DispalyName { get; set; }

    [IndexField("_templatename")]
    public string TemplateName { get; set; }

    [IndexField("urllink")]
    public string Url { get; set; }

    [IndexField("page_description")]
    public string PageDescription { get; set; }

    [IndexField("exclude_from_search")]
    public bool ExcludeFromSearch { get; set; }

    [IndexField("typefacet")]
    public string Type { get; set; }
}

Search Code

var searchIndex = ContentSearchManager.GetIndex("MySearchIndex"); // Get the search index
var searchPredicate = GetSearchPredicate(searchTerm, "Page"); // Build the search predicate

using (var searchContext = searchIndex.CreateSearchContext()) // Get a context of the search index
{
    var searchResults = searchContext.GetQueryable<SearchModel>().Filter(searchPredicate); // Search the index for items which match the predicate
    var searchFacets = searchContext.GetQueryable<SearchModel>().Filter(searchPredicate).FacetOn(x => x.Type).GetFacets(); // Gets facets - useful when you get paged results
    
    // This will get all of the results, which is not reccomended
    var fullResults = searchResults.GetResults();
                
    // This is better and will get paged results - page 1 with 10 results per page
    //var pagedResults = searchResults.Page(1, 10).GetResults();
}