SimpleLucene library

Goal

Provide a simple interface on Zend_Lucene library for: maintenance index, add documents to the index, search in the index.

Usage

The lucene index stores documents. If you add a new version of a document, you have to remove the previous version before. Every lucene document has a related "object".

The DocumentProviderInterface provides a simple interface to create lucene document. This way is is possible to create Zend_Lucene_Document by the object itself, or delegate the task to another object.

ex.

class Foo implements SimpleLucene_DocumentProviderInterface
{
    public $id;
    public $title;
    public $description;
    // ...
    
    function getLuceneDocument($foo)
    {
        $doc = new Zend_Search_Lucene_Document();
        return $doc
            ->addField(Zend_Search_Lucene_Field::unIndexed('_id', $this->id, 'utf-8'))
            ->addField(Zend_Search_Lucene_Field::Text('title', $this->title, 'utf-8'))
            ->addField(Zend_Search_Lucene_Field::unStored('description', $this->description, 'utf-8'));
    }

    function getLuceneDocumentUniqueId($foo)
    {
        return sha1('Foo:'.$this->id);
    }
    
    // ...
}

or delegate

class FooDocumentProvider implements SimpleLucene_DocumentProviderInterface
{
    function getLuceneDocument($foo)
    {
        $doc = new Zend_Search_Lucene_Document();
        return $doc
            ->addField(Zend_Search_Lucene_Field::unIndexed('_id', $foo->id, 'utf-8'))
            ->addField(Zend_Search_Lucene_Field::Text('title', $foo->title, 'utf-8'))
            ->addField(Zend_Search_Lucene_Field::unStored('description', $foo->description, 'utf-8'));
    }

    function getLuceneDocumentUniqueId($foo)
    {
        return sha1('Foo:'.$foo->id);
    }
}

Add documents to the index

Lets follow the example. Add foo document to the index.

$lucene = new SimpleLucene_Manager($index_dir);
$foo = new Foo;

// when Foo implements the document provider interface
$lucene->removeFromIndex($foo);
$lucene->addToIndex($foo);

// when Foo delegate the document provider interface
$lucene->addDocumentProvider('Foo', new FooDocumentProvider);
$lucene->removeFromIndex($foo);
$lucene->addToIndex($foo);

Search in the index

You have to create a search query object.

class FooSearchQuery implements SimpleLucene_SearchQueryInterface
{
    function getLuceneSearchQuery($phrase)
    {
        $query = new Zend_Search_Lucene_Search_Query_Boolean();

        foreach (explode(' ', $phrase) as $part) {
            $part = "$part~";
            
            $pattern = new Zend_Search_Lucene_Index_Term($part, 'title');
            $query->addSubQuery(new Zend_Search_Lucene_Search_Query_Fuzzy($pattern));
            
            $pattern = new Zend_Search_Lucene_Index_Term($part, 'description');
            $query->addSubQuery(new Zend_Search_Lucene_Search_Query_Fuzzy($pattern));
        }
        return $query;
    }
}

When you search just create a manager, set the search query from above, and search.

$lucene = new SimpleLucene_Manager($index_dir);
$lucene->setSearchQuery(new FooSearchQuery);
$lucene->search('foo and bar');

Index optimization

Over and over again the index starts growing large and working slower and slower. It will contain irrelevant/obsoleted documents. You have to clean up the mess. Lets do it.

$lucene = new SimpleLucene_Manager($index_dir);
$lucene->optimize();

Symfony related stuff

The symfony manager provides a listenToChanges method, which can listen to events indexable object changes. For example: admin.save_object or admin.delete_object. You can register it to those events.

$lucene = new SimpleLucene_Manager($index_dir);

$dispatcher->connect('admin.save_object', array($lucene, 'listenToChanges'));

Thats all. It will looking for sfEvent instance object attribute. Any object that implements SimpleLucene_DocumentProviderInterface is indexable. Otherwise you have to register a document provider before you do anything.

$lucene = new SimpleLucene_Manager($index_dir);
$lucene->addDocumentProvider('Foo', new FooDocumentProvider);

$dispatcher->connect('admin.save_object', array($lucene, 'listenToChanges'));

Tipps and tricks

The library supports multiple index: just create a new instance on different index directory.