8.3. Highlighting query terms

The contrib highlighter module fragments and highlights text based on a Lucene query. Highlighter was originally contributed by Mark Harwood, but many others have since joined in. Giving end users some context around specific term hits from their searches is a powerful way for them to judge how relevant each hit is. Often, a brief glimpse of the surrounding context of the search terms is enough to know if that result is worth investigating further. Each hit includes some number of fragments of the matching document highlighting the terms of the query. Figure 8.7 shows an example of highlighting part of the text from chapter 3, based on a term query for term. The source code for this is shown in listing 8.2. Like spell correction, covered in section 8.5, the web search engines have established this feature as a baseline requirement that all other search engines are expected to have.

Figure 8.7. Highlighting matching query terms within text