Augment search results with highlighted excerpts.

Adding relevant excerpts with highlighted search terms to your search results display makes it much easier for end users to scan the page and assess which hits look promising, dramatically improving their search experience.

Adaptations to indexer.pl

Highlighter uses information generated at index time. To save resources, highlighting is disabled by default and must be turned on for individual fields.

    {
        String *field_str = Str_newf("content");
        FullTextType *type = FullTextType_new((Analyzer*)analyzer);
        FullTextType_Set_Highlightable(type, true);
        Schema_Spec_Field(schema, field_str, (FieldType*)type);
        DECREF(type);
        DECREF(field_str);
    }

Adaptations to search.cgi

To add highlighting and excerpting to the search.cgi sample app, create a $highlighter object outside the hits iterating loop…

    String *content_str = Str_newf("content");
    Highlighter *highlighter
        = Highlighter_new((Searcher*)searcher, (Obj*)query,
                          content_str, 200);

… then modify the loop and the per-hit display to generate and include the excerpt.

    String *title_str = Str_newf("title");
    String *url_str   = Str_newf("url");
    HitDoc *hit;
    i = 1;

    // Loop over search results.
    while (NULL != (hit = Hits_Next(hits))) {
        String *title = (String*)HitDoc_Extract(hit, title_str);
        char *title_c = Str_To_Utf8(title);

        String *url = (String*)HitDoc_Extract(hit, url_str);
        char *url_c = Str_To_Utf8(url);

        String *excerpt = Highlighter_Create_Excerpt(highlighter, hit);
        char *excerpt_c = Str_To_Utf8(excerpt);

        printf("Result %d: %s (%s)\n%s\n\n", i, title_c, url_c, excerpt_c);

        free(excerpt_c);
        free(url_c);
        free(title_c);
        DECREF(excerpt);
        DECREF(url);
        DECREF(title);
        DECREF(hit);
        i++;
    }

    DECREF(url_str);
    DECREF(title_str);
    DECREF(hits);
    DECREF(query_str);
    DECREF(highlighter);
    DECREF(content_str);
    DECREF(searcher);
    DECREF(folder);

Next chapter: Query objects

Our next tutorial chapter, QueryObjectsTutorial, illustrates how to build an “advanced search” interface using Query objects instead of query strings.