The Lucene-based query handler implementation supports a pluggable spellchecker mechanism. By default, spell checking is not available and you have to configure it first. See the spellCheckerClass parameter on page Search Configuration. JCR currently provides an implementation class which uses the lucene-spellchecker to contribute. The dictionary is derived from the fulltext indexed content of the workspace and updated periodically. You can configure the refresh interval by picking one of the available inner classes of org.exoplatform.services.jcr.impl.core.query.lucene.spell.LuceneSpellChecker:

For example, if you want a refresh interval of six hours, the class name is org.exoplatform.services.jcr.impl.core.query.lucene.spell.LuceneSpellChecker$SixHoursRefreshInterval. If you use org.exoplatform.services.jcr.impl.core.query.lucene.spell.LuceneSpellChecker, the refresh interval will be one hour.

The spell checker dictionary is stored as a lucene index under "index-dir"/spellchecker. If it does not exist, a background thread will create it on startup. Similarly, the dictionary refresh is also done in a background thread to not block regular queries.

How to use

You can do a spelling check of a fulltext statement either with an XPath or a SQL query:

// rep:spellcheck('explatform') will always evaluate to true

Query query = qm.createQuery("/jcr:root[rep:spellcheck('explatform')]/(rep:spellcheck())", Query.XPATH);

RowIterator rows = query.execute().getRows();

// the above query will always return the root node no matter what string we check

Row r = rows.nextRow();

// get the result of the spell checking

Value v = r.getValue("rep:spellcheck()");

if (v == null) {

   // no suggestion returned, the spelling is correct or the spell checker

   // does not know how to correct it.

} else {

   String suggestion = v.getString();

}

And the same using SQL:

// SPELLCHECK('exoplatform') will always evaluate to true

Query query = qm.createQuery("SELECT rep:spellcheck() FROM nt:base WHERE jcr:path = '/' AND SPELLCHECK('explatform')", Query.SQL);

RowIterator rows = query.execute().getRows();

// the above query will always return the root node no matter what string we check

Row r = rows.nextRow();

// get the result of the spell checking

Value v = r.getValue("rep:spellcheck()");

if (v == null) {

   // no suggestion returned, the spelling is correct or the spell checker

   // does not know how to correct it.

} else {

   String suggestion = v.getString();

}