Major edit
One year on and I was able to improve on the original code I posted to produce this:
My indexed entity:
@Entity
@Indexed
@AnalyzerDef(name = "myanalyzer",
// Split input into tokens according to tokenizer
tokenizer = @TokenizerDef(factory = WhitespaceTokenizerFactory.class), //
filters = { //
// Normalize token text to lowercase, as the user is unlikely to care about casing when searching for matches
@TokenFilterDef(factory = LowerCaseFilterFactory.class),
// Index partial words starting at the front, so we can provide Autocomplete functionality
@TokenFilterDef(factory = NGramFilterFactory.class, params = { @Parameter(name = "maxGramSize", value = "1024") }),
// Close filters & Analyzerdef
})
@Analyzer(definition = "myanalyzer")
public class Compound extends DomainObject {
public static String[] getSearchFields(){...}
...
}
All @Fields are tokenized and stored in the index; required for this to work:
@Field(index = Index.TOKENIZED, store = Store.YES)
@Transactional(readOnly = true)
public synchronized List<String> getSuggestions(final String searchTerm) {
// Compose query for term over all fields in Compound
String lowerCasedSearchTerm = searchTerm.toLowerCase();
// Create a fullTextSession for the sessionFactory.getCurrentSession()
FullTextSession fullTextSession = Search.getFullTextSession(getSession());
// New DSL based query composition
SearchFactory searchFactory = fullTextSession.getSearchFactory();
QueryBuilder buildQuery = searchFactory.buildQueryBuilder().forEntity(Compound.class).get();
TermContext keyword = buildQuery.keyword();
WildcardContext wildcard = keyword.wildcard();
String[] searchfields = Compound.getSearchfields();
TermMatchingContext onFields = wildcard.onField(searchfields[0]);
for (int i = 1; i < searchfields.length; i++)
onFields.andField(searchfields[i]);
TermTermination matching = onFields.matching(input.toLowerCase());
Query query = matching.createQuery();
// Convert the Search Query into something that provides results: Specify Compound again to be future proof
FullTextQuery fullTextQuery = fullTextSession.createFullTextQuery(query, Compound.class);
fullTextQuery.setMaxResults(20);
// Projection does not work on collections or maps which are indexed via @IndexedEmbedded
List<String> projectedFields = new ArrayList<String>();
projectedFields.add(ProjectionConstants.DOCUMENT);
List<String> embeddedFields = new ArrayList<String>();
for (String fieldName : searchfields)
if (fieldName.contains("."))
embeddedFields.add(fieldName);
else
projectedFields.add(fieldName);
@SuppressWarnings("unchecked")
List<Object[]> results = fullTextQuery.setProjection(projectedFields.toArray(new String[projectedFields.size()])).list();
// Keep a list of suggestions retrieved by search over all fields
List<String> suggestions = new ArrayList<String>();
for (Object[] projectedObjects : results) {
// Retrieve the search suggestions for the simple projected field values
for (int i = 1; i < projectedObjects.length; i++) {
String fieldValue = projectedObjects[i].toString();
if (fieldValue.toLowerCase().contains(lowerCasedSearchTerm))
suggestions.add(fieldValue);
}
// Extract the search suggestions for the embedded fields from the document
Document document = (Document) projectedObjects[0];
for (String fieldName : embeddedFields)
for (Field field : document.getFields(fieldName))
if (field.stringValue().toLowerCase().contains(lowerCasedSearchTerm))
suggestions.add(field.stringValue());
}
// Return the composed list of suggestions, which might be empty
return suggestions;
}
There's some wrangling I'm doing at the end to handle @IndexedEmbedded fields. If you dont have those you can simplify the code a whole lot merely projecting the searchFields, and leaving out the document & embeddedField handling.
As before:
Hopefully this is useful to the next person to encounter this question. Should anyone have any critique or improvements to the above posted code, feel free to edit and do please let me know.
Edit3: The project this code was taken from has since been open sourced; Here are the relevant classes:
https://trac.nbic.nl/metidb/browser/trunk/metidb/metidb-core/src/main/java/org/metidb/domain/Compound.java
https://trac.nbic.nl/metidb/browser/trunk/metidb/metidb-core/src/main/java/org/metidb/dao/CompoundDAOImpl.java
https://trac.nbic.nl/metidb/browser/trunk/metidb/metidb-search/src/main/java/org/metidb/search/text/Autocompleter.java
