Intracto Elastic Synonym

This library reads/writes elasticsearch synonyms and converts them into an array of editable objects. A refresh action can be called whenever you want to make the updated synonyms available for your users.

See intracto/elastic-synonym-bundle for a plug-and-play implementation for symfony 4.4+ using bootstrap.

Note: make sure you're using a query that supports analyzing, like the regular match filter (example below).

Additional requirements:

• Elasticsearch 7.3+
• Synonym filter must be applied to the search analyzer. It won't work for index analyzers

Installation

$ composer require intracto/elastic_synonym

Synonym file on filesystem

There are a few limitations we need to work around:

• Elasticsearch will only read wherever the current config file is located (usually /etc/elasticsearch)
• Our webuser on the filesystem will propably have not the permissions to write to the desired directory.

This is why we choose to work with a symlink. This can also be implemented as you want, but here is a working example using vagrant:

$ mkdir /vagrant/.elastic-synonym
$ touch /vagrant/.elastic-synonym/synonyms.txt # name the file anyway you want

$ sudo ln -s /vagrant/.elastic-synonym /etc/elasticsearch/analytics

Synonym filter in elastic

Add the following filter under settings.analysis.filter:

'my_synonyms' => [ // a name for your filter
    'type' => 'synonym_graph',
    'synonyms_path' => 'analytics/synonyms.txt', // This needs to be the path inside /etc/elastic.
    'updateable' => true, // *must* be true
],

If you want to add it to your default search analyzer, add the following settings under settings.analysis.analyzer:

'default_search' => [
    // ..
    'filter' => [/*'..', */'my_synonyms'],
],

A simple example (assuming you're using defaults and added the filter to your default_search):

$body['query']['bool']['should'][] = ['match' => ['description' => [
    'query' => 'this is an example',
    'fuzziness' => 'AUTO',
    'operator' => 'OR',
]]];