=encoding utf8

=head1 NAME

Apache::Solr - Apache Solr (Lucene) extension

=head1 INHERITANCE

 Apache::Solr is extended by
   Apache::Solr::JSON
   Apache::Solr::XML

=head1 SYNOPSIS

  # use Log::Report mode => "DEBUG";
  my $solr    = Apache::Solr->new(server => $url);

  my $doc     = Apache::Solr::Document->new(...);
  my $results = $solr->addDocument($doc);
  $results or die $results->errors;

  my $results = $solr->select(q => 'author:mark');
  my $doc     = $results->selected(3);
  print $doc->_author;

  my $results = $solr->select(q => "really", hl => {fl=>'content'});
  while(my $doc = $results->nextSelected)
  {   my $hldoc = $results->highlighted($doc);
      print $hldoc->_content;
      ...
  }

  # based on Log::Report, hence (for communication errors and such)
  use Log::Report;
  dispatcher SYSLOG => 'default';  # now all warnings/error to syslog
  try { $solr->select(...) }; print $@->wasFatal;

=head1 DESCRIPTION

Solr is a stand-alone full-text search-engine (based on Lucent), with
loads of features.  This module tries to provide a high level interface
to the Solr server.

See F<F<http://wiki.apache.org/solr/> and F<http://lucene.apache.org/solr/>

=head1 METHODS

=head2 Constructors

=over 4

=item Apache::Solr-E<gt>B<new>(%options)

Create a client to connect to one "core" (collection) of the Solr
server.

 -Option        --Default
  agent           <created internally>
  autocommit      true
  core            undef
  format          'XML'
  server          <required>
  server_version  <latest>

=over 2

=item agent => LWP::UserAgent object

Agent which implements the communication between this client and the
Solr server.

When you have multiple C<Apache::Solr> objects in your program, you may
want to share this agent, to share the connection. Since [0.94], this
will happen automagically: the parameter defaults to the agent created
for the previous object.

Do not forget to install LWP::Protocol::https if you need to connect
via https.

=item autocommit => BOOLEAN

Commit all changes immediately unless specified differently.

=item core => NAME

Set the core name to be addressed by this client. When there is no core
name specified, the core is selected by the server or already part of
the URL.

You probably want to set-up a core dedicated for testing and one for
the live environment.

=item format => 'XML'|'JSON'

Communication format between client and server.  You may also instantiate
L<Apache::Solr::XML|Apache::Solr::XML> or L<Apache::Solr::JSON|Apache::Solr::JSON> directly.

=item server => URL

The locations of the Solr server depends on the way the java environment
is set-up.   The URL is either an URI object or a string which can be
instantiated as such.

=item server_version => VERSION

By default the latest version of the server software, currently 4.5.
Try to get this setting right, because it will help you a lot in correct
parameter use and support for the right features.

=back

=back

=head2 Accessors

=over 4

=item $obj-E<gt>B<agent>()

Returns the LWP::UserAgent object which maintains the connection to
the server.

=item $obj-E<gt>B<autocommit>( [BOOLEAN] )

=item $obj-E<gt>B<core>( [$core] )

Returns the $core, when not defined the default core as set by L<new(core)|Apache::Solr/"Constructors">.
May return C<undef>.

=item $obj-E<gt>B<server>( [$uri|STRING] )

Returns the URI object which refers to the server base address.  You need
to clone() it before modifying.  You may set a new value as STRING or C<$uri>
object.

=item $obj-E<gt>B<serverVersion>()

Returns the specified version of the Solr server software (by default the
latest).  Treat this version as string, to avoid rounding errors.

=back

=head2 Commands

=head3 Search

=over 4

=item $obj-E<gt>B<queryTerms>($terms)

Search for often used terms. See F<http://wiki.apache.org/solr/TermsComponent>

$terms are passed to L<expandTerms()|Apache::Solr/"Parameter pre-processing"> before being used.

B<Be warned:> The result is not sorted when XML communication is used,
even when you explicitly request it.

example: 

  my $r = $self->queryTerms(fl => 'subject', limit => 100);
  if($r->success)
  {   foreach my $hit ($r->terms('subject'))
      {   my ($term, $count) = @$hit;
          print "term=$term, count=$count\n";
      }
  }

  if(my $r = $self->queryTerms(fl => 'subject', limit => 100))
     ...

=item $obj-E<gt>B<select>($parameters)

Find information in the document collection.

This method has a HUGE number of parameters.  These values are passed in
the uri of the http query to the solr server.  See L<expandSelect()|Apache::Solr/"Parameter pre-processing"> for
all the simplifications offered here.  Sets of there parameters
may need configuration help in the server as well.

=back

=head3 Updates

See F<http://wiki.apache.org/solr/UpdateXmlMessages>.  Missing are the
atomic updates.

=over 4

=item $obj-E<gt>B<addDocument>( <$doc|ARRAY>, %options )

Add one or more documents (L<Apache::Solr::Document|Apache::Solr::Document> objects) to the Solr
database on the server.

 -Option            --Default
  allowDups           <false>
  commit              <autocommit>
  commitWithin        undef
  overwrite           <true>
  overwriteCommitted  <not allowDups>
  overwritePending    <not allowDups>

=over 2

=item allowDups => BOOLEAN

[removed since Solr 4.0]  Use option C<overwrite>.

=item commit => BOOLEAN

=item commitWithin => SECONDS

[Since Solr 3.4] Automatically translated into 'commit' for older
servers.  Currently, the resolution is milli-seconds.

=item overwrite => BOOLEAN

=item overwriteCommitted => BOOLEAN

[removed since Solr 4.0]  Use option C<overwrite>.

=item overwritePending => BOOLEAN

[removed since Solr 4.0]  Use option C<overwrite>.

=back

=item $obj-E<gt>B<commit>(%options)

 -Option        --Default
  expungeDeletes  <false>
  softCommit      <false>
  waitFlush       <true>
  waitSearcher    <true>

=over 2

=item expungeDeletes => BOOLEAN

[since Solr 1.4]

=item softCommit => BOOLEAN

[since Solr 4.0]

=item waitFlush => BOOLEAN

[before Solr 1.4, removed in 4.0]

=item waitSearcher => BOOLEAN

=back

=item $obj-E<gt>B<delete>(%options)

Remove one or more documents, based on id or query.

 -Option       --Default
  commit         <autocommit>
  fromCommitted  true
  fromPending    true
  id             undef
  query          undef

=over 2

=item commit => BOOLEAN

When specified, it indicates whether to commit (update the indexes) after
the last delete.  By default the value of L<new(autocommit)|Apache::Solr/"Constructors">.

=item fromCommitted => BOOLEAN

[deprecated since ?]

=item fromPending => BOOLEAN

[deprecated since ?]

=item id => ID|ARRAY-of-IDs

The expected content of the uniqueKey fields (usually named C<id>) for
the documents to be removed.

=item query => QUERY|ARRAY-of-QUERYs

=back

=item $obj-E<gt>B<extractDocument>(%options)

Call the Solr Tika built-in to have the server translate various
kinds of structured documents into Solr searchable documents.  This
component is also called "Solr Cell".

The %options are mostly passed on as attributes to the server call,
but there are a few more.  You need to pass either a C<file> or
C<string> with data.

See F<http://wiki.apache.org/solr/ExtractingRequestHandler>

 -Option      --Default
  commit        new(autocommit)
  content_type  <from> filename
  file          undef
  string        undef

=over 2

=item commit => BOOLEAN

[0.94] commit the document to the database.

=item content_type => MIME

=item file => FILENAME|FILEHANDLE

Either C<file> or C<string> must be used.

=item string => STRING|SCALAR

The document provided as normal text or a reference to raw text.  You may
also specify the C<file> option with a filename.

=back

example: 

   my $r = $solr->extractDocument(file => 'design.pdf'
     , literal_id => 'host');

=item $obj-E<gt>B<optimize>(%options)

 -Option      --Default
  maxSegments   1
  softCommit    <false>
  waitFlush     <true>
  waitSearcher  <true>

=over 2

=item maxSegments => INTEGER

[since Solr 1.3]

=item softCommit => BOOLEAN

[since Solr 4.0]

=item waitFlush => BOOLEAN

[before Solr 1.4, removed from 4.0]

=item waitSearcher => BOOLEAN

=back

=item $obj-E<gt>B<rollback>()

[solr 1.4]

=back

=head3 Core management

See F<http://lucidworks.lucidimagination.com/display/solr/Configuring+solr.xml>
The CREATE, SWAP, ALIAS, and RENAME actions are not yet supported, because
they are not very useful, it seems.

=over 4

=item $obj-E<gt>B<coreReload>( [$core] )

[0.94] Load a new core (on the server) from the configuration of this
core. While the new core is initializing, the existing one will continue
to handle requests. When the new Solr core is ready, it takes over and
the old core is unloaded.

 -Option--Default
  core    <this core>

=over 2

=item core => NAME

=back

example: 

  my $result = $solr->coreReload;
  $result or die $result->errors;

=item $obj-E<gt>B<coreStatus>()

[0.94] Returns a HASH with information about this core.  There is no
description about the exact structure and interpretation of this data.

 -Option--Default
  core    <this core>

=over 2

=item core => NAME

=back

example: 

  my $result = $solr->coreStatus;
  $result or die $result->errors;

  use Data::Dumper;
  print Dumper $result->decoded->{status};

=item $obj-E<gt>B<coreUnload>(%options)

Removes a core from Solr. Active requests will continue to be processed, but no new requests will be sent to the named core. If a core is registered under more than one name, only the given name is removed.

 -Option--Default
  core    <this core>

=over 2

=item core => NAME

=back

=back

=head2 Helpers

=head3 Parameter pre-processing

Many parameters are passed to the server.  The syntax of the communication
protocol is not optimal for the end-user: it is too verbose and depends on
the Solr server version.

General rules:

=over 4

=item * you can group them on prefix

=item * use underscore as alternative to dots: less quoting needed

=item * boolean values in Perl will get translated into 'true' and 'false'

=item * when an ARRAY (or LIST), the order of the parameters get preserved

=back

=over 4

=item $obj-E<gt>B<deprecated>($message)

Produce a warning $message about deprecated parameters with the
indicated server version.

=item $obj-E<gt>B<expandExtract>(PAIRS|ARRAY)

Used by L<extractDocument()|Apache::Solr/"Updates">.

[0.93] If the key is C<literal> or C<literals>, then the keys in the
value HASH (or ARRAY of PAIRS) get 'literal.' prepended.  "Literals"
are fields you add yourself to the SolrCEL output.  Unless C<extractOnly>,
you need to specify the 'id' literal.

[0.94] You can also use C<fmap>, C<boost>, and C<resource> with an
HASH (or ARRAY-of-PAIRS).  [0.97] the value in each PAIR may be a SCALAR
(ref string) which circumvents some copying.

example: 

  my $result = $solr->extractDocument(string => $document
     , resource_name => $fn, extractOnly => 1
     , literals => { id => 5, b => 'tic' }, literal_xyz => 42
     , fmap => { id => 'doc_id' }, fmap_subject => 'mysubject'
     , boost => { abc => 3.5 }, boost_xyz => 2.0);
);

=item $obj-E<gt>B<expandSelect>(PAIRS)

The L<select()|Apache::Solr/"Search"> method accepts many, many parameters.  These are passed
to modules in the server, which need configuration before being usable.

Besides the common parameters, like 'q' (query) and 'rows', there
are parameters for various (pluggable) backends, usually prefixed
by the backend abbreviation.

=over 4

=item * facet -> F<http://wiki.apache.org/solr/SimpleFacetParameters>

=item * hl (highlight) -> F<http://wiki.apache.org/solr/HighlightingParameters>

=item * mtl -> F<http://wiki.apache.org/solr/MoreLikeThis>

=item * stats -> F<http://wiki.apache.org/solr/StatsComponent>

=item * group -> F<http://wiki.apache.org/solr/FieldCollapsing>

=back

You may use WebService::Solr::Query to construct the query ('q').

example: 

  my @r = $solr->expandSelect
    ( q => 'inStock:true', rows => 10
    , facet => {limit => -1, field => [qw/cat inStock/], mincount => 1}
    , f_cat_facet => {missing => 1}
    , hl    => {}
    , mlt   => { fl => 'manu,cat', mindf => 1, mintf => 1 }
    , stats => { field => [ 'price', 'popularity' ] }
    , group => { query => 'price:[0 TO 99.99]', limit => 3 }
     );

  # becomes (one line)
  ...?rows=10&q=inStock:true
    &facet=true&facet.limit=-1&facet.field=cat
       &f.cat.facet.missing=true&facet.mincount=1&facet.field=inStock
    &mlt=true&mlt.fl=manu,cat&mlt.mindf=1&mlt.mintf=1
    &stats=true&stats.field=price&stats.field=popularity
    &group=true&group.query=price:[0+TO+99.99]&group.limit=3

=item $obj-E<gt>B<expandTerms>(PAIRS|ARRAY)

Used by L<queryTerms()|Apache::Solr/"Search"> only.

example: 

  my @t = $solr->expandTerms('terms.lower.incl' => 'true');
  my @t = $solr->expandTerms([lower_incl => 1]);   # same

  my $r = $self->queryTerms(fl => 'subject', limit => 100);

=item $obj-E<gt>B<ignored>($message)

Produce a warning $message about parameters which will get ignored
because they were not yet supported by the indicated server version.

=item $obj-E<gt>B<removed>($message)

Produce a warning $message about parameters which will not be passed on,
because they were removed from the indicated server version.

=back

=head3 Other helpers

=over 4

=item $obj-E<gt>B<endpoint>($action, %options)

Compute the address to be called (for HTTP)

 -Option--Default
  core    new(core)
  params  []

=over 2

=item core => NAME

If no core is specified, the default of the server is addressed.

=item params => HASH|ARRAY-of-pairs

The order of the parameters will be preserved when an ARRAY or parameters
is passed; you never know for a HASH.

=back

=back

=head1 DETAILS

=head2 Comparison with other implementations

=head3 Compared to WebService::Solr

WebService::Solr is a good module, with a lot of miles.  The main
differences is that C<Apache::Solr> has much more abstraction.

=over 4

=item * simplified parameter syntax, improving readibility

=item * real Perl-level boolean parameters, not 'true' and 'false'

=item * warnings for deprecated and ignored parameters

=item * smart result object with built-in trace and timing

=item * hidden paging of results

=item * flexible logging framework (Log::Report)

=item * both-way XML or both-way JSON, not requests in XML and answers in JSON

=item * access to plugings like terms and tika

=item * no Moose

=back

=head1 SEE ALSO

This module is part of Apache-Solr distribution version 1.05,
built on January 11, 2019. Website: F<http://perl.overmeer.net/CPAN/>

=head1 LICENSE

Copyrights 2012-2019 by [Mark Overmeer]. For other contributors see ChangeLog.

This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
See F<http://dev.perl.org/licenses/>