silverstripe-fulltextsearch/docs/en/Solr.md

Solr connector for SilverStripe fulltextsearch module

Introduction

The fulltextsearch module includes support for connecting to Solr.

It works with Solr in multi-core mode. It needs to be able to update Solr configuration files, and has modes for doing this by direct file access (when Solr shares a server with SilverStripe) and by WebDAV (when it's on a different server).

See the helpful Solr Tutorial, for more on cores and querying.

Requirements

Since Solr is Java based, it requires Java 1.5 or greater installed.

When you're installing it yourself, it also requires a servlet container such as Tomcat, Jetty, or Resin. For development testing there is a standalone version that comes bundled with Jetty (see below).

See the official Solr installation docs for more information.

Note that these requirements are for the Solr server environment, which doesn't have to be the same physical machine as the SilverStripe webhost.

Installation (Local)

Get the Solr server

composer require silverstripe/fulltextsearch-localsolr 4.5.1.x-dev

Start the server (via CLI, in a separate terminal window or background process)

cd fulltextsearch-localsolr/server/
java -jar start.jar

Configure the fulltextsearch Solr component to use the local server

Configure Solr in file mode. The 'path' directory has to be writeable by the user the Solr search server is started with (see below).

// File: mysite/_config.php:
<?php
Solr::configure_server(array(
	'host' => 'localhost',
	'indexstore' => array(
		'mode' => 'file',
		'path' => BASE_PATH . '/.solr'
	)
));

Note: We recommend to put the indexstore.path directory outside of the webroot. If you place it inside of the webroot (as shown in the example), please ensure its contents are not accessible through the webserver. This can be achieved by server configuration, or (in most configurations) also by marking the folder as hidden via a "dot" prefix.

Create an index

// File: mysite/code/MyIndex.php:
<?php
class MyIndex extends SolrIndex {
	function init() {
		$this->addClass('Page');
		$this->addAllFulltextFields();
	}
}

Initialize the configuration (via CLI)

sake dev/tasks/Solr_Configure

Based on the sample configuration above, this command will do the following:

• Create a <BASE_PATH>/.solr/MyIndex folder
• Copy configuration files from fulltextsearch/conf/extras/ to <BASE_PATH>/.solr/MyIndex/conf
• Generate a schema.xml, and place it it in <BASE_PATH>/.solr/MyIndex/conf

If you call the Solr_configure task with an existing index folder, it will overwrite all files from their default locations, regenerate the schema.xml, and ask Solr to reload the configuration.

Usage

After configuring Solr, you have the option to add your existing content to its indices. Run the following command:

sake dev/tasks/Solr_Reindex

This will delete and rebuild all indices. Depending on your data, this can take anywhere from minutes to hours. Keep in mind that the normal mode of updating indices is based on ORM manipulations of the underlying data. For example, calling $myPage->write() will automatically update the index entry for this record (and all its variants).

This task has the following options:

• verbose: Debug information

Internally, depending on what job processing backend you have configured (such as queuedjobs) individual tasks for re-indexing groups of records may either be performed behind the scenes as crontasks, or via separate processes initiated by the current request.

Internally groups of records are grouped into sizes of 200. You can configure this group sizing by using the Solr_Reindex.recordsPerRequest config.

:::yaml
Solr_Reindex:
  recordsPerRequest: 150

Note: The Solr indexes will be stored as binary files inside your SilverStripe project. You can also copy the thirdparty/ solr directory somewhere else, just set the path value in mysite/_config.php to point to the new location.

File-based configuration (solrconfig.xml etc)

Many aspects of Solr are configured outside of the schema.xml file which SilverStripe generates based on the index PHP file. For example, stopwords are placed in their own stopwords.txt file, and spell checks are configured in solrconfig.xml.

By default, these files are copied from the fulltextsearch/conf/extras/ directory over to the new index location. In order to use your own files, copy these files into a location of your choosing (for example mysite/data/solr/), and tell Solr to use this folder with the extraspath configuration setting.

// mysite/_config.php
Solr::configure_server(array(
	// ...
	'extraspath' => Director::baseFolder() . '/mysite/data/solr/',
));

Please run the Solr_configure task for the changes to take effect.

Note: You can also define those on an index-by-index basis by implementing SolrIndex->getExtrasPath().

Custom Types

Solr supports custom field type definitions which are written to its XML schema. Many standard ones are already included in the default schema. As the XML file is generated dynamically, we can add our own types by overloading the template responsible for it: types.ss.

In the following example, we read out type definitions from a new file mysite/solr/templates/types.ss instead:

<?php
class MyIndex extends SolrIndex {
	function getTypes() {
		return $this->renderWith(Director::baseFolder() . '/mysite/solr/templates/types.ss');
	}
}

Spell Checking ("Did you mean...")

Solr has various spell checking strategies (see the "SpellCheckComponent" docs), all of which are configured through solrconfig.xml. In the default config which is copied into your index, spell checking data is collected from all fulltext fields (everything you added through SolrIndex->addFulltextField()). The values of these fields are collected in a special _text field.

$index = new MyIndex();
$query = new SearchQuery();
$query->search('My Term');
$params = array('spellcheck' => 'true', 'spellcheck.collate' => 'true');
$results = $index->search($query, -1, -1, $params);
$results->spellcheck

The built-in _text data is better than nothing, but also has some problems: Its heavily processed, for example by stemming filters which butcher words. So misspelling "Govnernance" will suggest "govern" rather than "Governance". This can be fixed by aggregating spell checking data in a separate

<?php
class MyIndex extends SolrIndex {

	function init() {
		// ...
		$this->addCopyField('SiteTree_Title', 'spellcheckData');
		$this->addCopyField('DMSDocument_Title', 'spellcheckData');
		$this->addCopyField('SiteTree_Content', 'spellcheckData');
		$this->addCopyField('DMSDocument_Content', 'spellcheckData');
	}

	// ...

	function getFieldDefinitions() {
		$xml = parent::getFieldDefinitions();
		
		$xml .= "\n\n\t\t<!-- Additional custom fields for spell checking -->";
		$xml .= "\n\t\t<field name='spellcheckData' type='textSpellHtml' indexed='true' stored='false' multiValued='true' />";

		return $xml;
	}

}

Now you need to tell solr to use our new field for gathering spelling data. In order to customize the spell checking configuration, create your own solrconfig.xml (see "File-based configuration"). In there, change the following directive:

<!-- ... -->
<searchComponent name="spellcheck" class="solr.SpellCheckComponent">
	<!-- ... -->
	<str name="field">spellcheckData</str>
</searchComponent

Don't forget to copy the new configuration via a call to the Solr_Configure task, and reindex your data before using the spell checker.

Limiting search fields

Solr has a way of specifying which fields to search on. You specify these fields as a parameter to SearchQuery.

In the following example, we're telling Solr to only search the Title and Content fields. Note that the fields must be specified in the search parameters as "composite fields", which means they should be specified in the form of {table}_{field}.

These fields are defined in the schema.xml file that gets sent to Solr.

$query = new SearchQuery();
$query->classes = array(array('class' => 'Page', 'includeSubclasses' => true));
$query->search('someterms', array('SiteTree_Title', 'SiteTree_Content'));
$result = singleton('SolrSearchIndex')->search($query, -1, -1);

// the request to Solr would be:
// q=(SiteTree_Title:Lorem+OR+SiteTree_Content:Lorem)

Configuring boosts

There are several ways in which you can configure boosting on search fields or terms.

Boosting on search query

Solr has a way of specifying which fields should be boosted as a parameter to SearchQuery.

This means if you boost a certain field, search query matches on that field will be considered higher relevance than other fields with matches, and therefore those results will be closer to the top of the results.

In this example, we enter "Lorem" as the search term, and boost the Content field:

$query = new SearchQuery();
$query->classes = array(array('class' => 'Page', 'includeSubclasses' => true));
$query->search('Lorem', null, array('SiteTree_Content' => 2));
$result = singleton('SolrSearchIndex')->search($query, -1, -1);

// the request to Solr would be:
// q=SiteTree_Content:Lorem^2

More information on relevancy on the Solr wiki.

Boosting on index fields

Boost values for specific can also be specified directly on the SolrIndex class directly.

The following methods can be used to set one or more boosted fields:

• SolrIndex::addBoostedField Adds a field with a specific boosted value (defaults to 2)
• SolrIndex::setFieldBoosting If a field has already been added to an index, the boosting value can be customised, changed, or reset for a single field.
• SolrIndex::addFulltextField A boost can be set for a field using the $extraOptions parameter with the key boost assigned to the desired value.

For example:

:::php
class SolrSearchIndex extends SolrIndex {

	public function init() {
		$this->addClass('SiteTree');
		$this->addAllFulltextFields();
		$this->addFilterField('ShowInSearch');
		this->addBoostedField('Title', null, array(), 1.5);
		this->setFieldBoosting('SiteTree_SearchBoost', 2);
	}

}

Custom Types

Solr supports custom field type definitions which are written to its XML schema. Many standard ones are already included in the default schema. As the XML file is generated dynamically, we can add our own types by overloading the template responsible for it: types.ss.

In the following example, we read out type definitions from a new file mysite/solr/templates/types.ss instead:

<?php
class MyIndex extends SolrIndex {
	function getTemplatesPath() {
		return Director::baseFolder() . '/mysite/solr/templates/';
	}
}

Highlighting

Solr can highlight the searched terms in context of the matched content, to help users determine the relevancy of results (e.g. in which part of a sentence the term is used). In order to use this feature, the full content of the field to be highlighted needs to be stored in the index, by declaring it through addStoredField().

<?php
class MyIndex extends SolrIndex {
	function init() {
		$this->addClass('Page');
		$this->addAllFulltextFields();
		$this->addStoredField('Content');
	}
}

To search with highlighting enabled, you need to pass in a custom query parameter. There's a lot more parameters to tweak results on the Solr Wiki.

$index = new MyIndex();
$query = new SearchQuery();
$query->search('My Term');
$results = $index->search($query, -1, -1, array('hl' => 'true'));

Each result will automatically contain an "Excerpt" property which you can use in your own results template. The searched term is highlighted with an <em> tag by default.

Note: It is recommended to strip out all HTML tags and convert entities on the indexed content, to avoid matching HTML attributes, and cluttering highlighted content with unparsed HTML.

Adding additional information into search results

Inside the SolrIndex::search() function, the third-party library solr-php-client is used to send data to Solr and parse the response. Additional information can be pulled from this response and added to your results object for use in templates using the updateSearchResults() extension hook.

$index = new MyIndex();
$query = new SearchQuery();
$query->search('My Term');
$results = $index->search($query, -1, -1, array(
	'facet' => 'true',
	'facet.field' => 'SiteTree_ClassName',
));

By adding facet fields into the query parameters, our response object from Solr now contains some additional information that we can add into the results sent to the page.

<?php
class MyResultsExtension extends Extension {
	/**
	 * Adds extra information from the solr-php-client repsonse
	 * into our search results.
	 * @param $results The ArrayData that will be used to generate search
	 *        results pages.
	 * @param $response The solr-php-client response object.
	 */
	public function updateSearchResults($results, $response)
	{
		if (!isset($response->facet_counts) || !isset($response->facet_counts->facet_fields)) {
			return;
		}
		$facetCounts = ArrayList::create(array());
		foreach($response->facet_counts->facet_fields as $name => $facets) {
			$facetDetails = ArrayData::create(array(
				'Name' => $name,
				'Facets' => ArrayList::create(array()),
			));
			foreach($facets as $facetName => $facetCount) {
				$facetDetails->Facets->push(ArrayData::create(array(
					'Name' => $facetName,
					'Count' => $facetCount,
				)));
			}
			$facetCounts->push($facetDetails);
		}
		$results->setField('FacetCounts', $facetCounts);
	}
}

We can now access the facet information inside our templates.

Adding Analyzers, Tokenizers and Token Filters

When a document is indexed, its individual fields are subject to the analyzing and tokenizing filters that can transform and normalize the data in the fields. For example — removing blank spaces, removing html code, stemming, removing a particular character and replacing it with another (see Solr Wiki).

Example: Replace synonyms on indexing (e.g. "i-pad" with "iPad")

<?php
class MyIndex extends SolrIndex {
	function init() {
		$this->addClass('Page');
		$this->addField('Content');
		$this->addAnalyzer('Content', 'filter', array('class' => 'solr.SynonymFilterFactory'));
	}
}

// Generates the following XML schema definition:
// <field name="Page_Content" ...>
//   <filter class="solr.SynonymFilterFactory" synonyms="syn.txt" ignoreCase="true" expand="false"/>
// </field>

Text Extraction

Solr provides built-in text extraction capabilities for PDF and Office documents, and numerous other formats, through the ExtractingRequestHandler API (see http://wiki.apache.org/solr/ExtractingRequestHandler). If you're using a default Solr installation, it's most likely already bundled and set up. But if you plan on running the Solr server integrated into this module, you'll need to download the libraries and link the first.

wget http://archive.apache.org/dist/lucene/solr/3.1.0/apache-solr-3.1.0.tgz
mkdir tmp
tar -xvzf apache-solr-3.1.0.tgz
mkdir .solr/PageSolrIndexboot/dist
mkdir .solr/PageSolrIndexboot/contrib
cp apache-solr-3.1.0/dist/apache-solr-cell-3.1.0.jar .solr/PageSolrIndexboot/dist/
cp -R apache-solr-3.1.0/contrib/extraction .solr/PageSolrIndexboot/contrib/
rm -rf apache-solr-3.1.0 apache-solr-3.1.0.tgz

Create a custom solrconfig.xml (see "File-based configuration"). Add the following XML configuration.

<lib dir="./contrib/extraction/lib/" />

Now apply the configuration:

sake dev/tasks/Solr_configure

Now you can use Solr text extraction either directly through the HTTP API, or indirectly through the "textextraction" module.

Debugging

Using the web admin interface

You can visit http://localhost:8983/solr, which will show you a list to the admin interfaces of all available indices. There you can search the contents of the index via the native SOLR web interface.

It is possible to manually replicate the data automatically sent to Solr when saving/publishing in SilverStripe, which is useful when debugging front-end queries, see thirdparty/fulltextsearch/server/silverstripe-solr-test.xml.

java -Durl=http://localhost:8983/solr/MyIndex/update/ -Dtype=text/xml -jar post.jar silverstripe-solr-test.xml

FAQ

How do I use date ranges where dates might not be defined?

The Solr index updater only includes dates with values, so the field might not exist in all your index entries. A simple bounded range query (<field>:[* TO <date>]) will fail in this case. In order to query the field, reverse the search conditions and exclude the ranges you don't want:

// Wrong: Filter will ignore all empty field values
$myQuery->filter(<field>, new SearchQuery_Range('*', <date>));
// Better: Exclude the opposite range
$myQuery->exclude(<field>, new SearchQuery_Range(<date>, '*'));