Lucy::Docs::Tutorial::BeyondSimUser3Contributed Perl DocumenLucy::Docs::Tutorial::BeyondSimple(3)



NAME
       Lucy::Docs::Tutorial::BeyondSimple - A more flexible app structure.

DESCRIPTION
   Goal
       In this tutorial chapter, we'll refactor the apps we built in Lucy::Docs::Tutorial::Simple
       so that they look exactly the same from the end user's point of view, but offer the
       developer greater possibilites for expansion.

       To achieve this, we'll ditch Lucy::Simple and replace it with the classes that it uses
       internally:

       ·   Lucy::Plan::Schema - Plan out your index.

       ·   Lucy::Plan::FullTextType - Field type for full text search.

       ·   Lucy::Analysis::EasyAnalyzer - A one-size-fits-all parser/tokenizer.

       ·   Lucy::Index::Indexer - Manipulate index content.

       ·   Lucy::Search::IndexSearcher - Search an index.

       ·   Lucy::Search::Hits - Iterate over hits returned by a Searcher.

   Adaptations to indexer.pl
       After we load our modules...

           use Lucy::Plan::Schema;
           use Lucy::Plan::FullTextType;
           use Lucy::Analysis::EasyAnalyzer;
           use Lucy::Index::Indexer;

       ... the first item we're going need is a Schema.

       The primary job of a Schema is to specify what fields are available and how they're
       defined.  We'll start off with three fields: title, content and url.

           # Create Schema.
           my $schema = Lucy::Plan::Schema->new;
           my $easyanalyzer = Lucy::Analysis::EasyAnalyzer->new(
               language => 'en',
           );
           my $type = Lucy::Plan::FullTextType->new(
               analyzer => $easyanalyzer,
           );
           $schema->spec_field( name => 'title',   type => $type );
           $schema->spec_field( name => 'content', type => $type );
           $schema->spec_field( name => 'url',     type => $type );

       All of the fields are spec'd out using the "FullTextType" FieldType, indicating that they
       will be searchable as "full text" -- which means that they can be searched for individual
       words.  The "analyzer", which is unique to FullTextType fields, is what breaks up the text
       into searchable tokens.

       Next, we'll swap our Lucy::Simple object out for a Lucy::Index::Indexer.  The substitution
       will be straightforward because Simple has merely been serving as a thin wrapper around an
       inner Indexer, and we'll just be peeling away the wrapper.

       First, replace the constructor:

           # Create Indexer.
           my $indexer = Lucy::Index::Indexer->new(
               index    => $path_to_index,
               schema   => $schema,
               create   => 1,
               truncate => 1,
           );

       Next, have the $indexer object "add_doc" where we were having the $lucy object "add_doc"
       before:

           foreach my $filename (@filenames) {
               my $doc = parse_file($filename);
               $indexer->add_doc($doc);
           }

       There's only one extra step required: at the end of the app, you must call commit()
       explicitly to close the indexing session and commit your changes.  (Lucy::Simple hides
       this detail, calling commit() implicitly when it needs to).

           $indexer->commit;

   Adaptations to search.cgi
       In our search app as in our indexing app, Lucy::Simple has served as a thin wrapper --
       this time around Lucy::Search::IndexSearcher and Lucy::Search::Hits.  Swapping out Simple
       for these two classes is also straightforward:

           use Lucy::Search::IndexSearcher;

           my $searcher = Lucy::Search::IndexSearcher->new(
               index => $path_to_index,
           );
           my $hits = $searcher->hits(    # returns a Hits object, not a hit count
               query      => $q,
               offset     => $offset,
               num_wanted => $page_size,
           );
           my $hit_count = $hits->total_hits;  # get the hit count here

           ...

           while ( my $hit = $hits->next ) {
               ...
           }

   Hooray!
       Congratulations!  Your apps do the same thing as before... but now they'll be easier to
       customize.

       In our next chapter, Lucy::Docs::Tutorial::FieldType, we'll explore how to assign
       different behaviors to different fields.



perl v5.20.2                                2015-12-01      Lucy::Docs::Tutorial::BeyondSimple(3)