Converters

In order to transform your objects and their properties into searchable text, and from data stored in the index back into objects, Compass has the notion of _converters_.

Compass acts as a registry of converters, each identified by name.

Compass includes many converters itself, some responsible for converting entire class instances and some for individual properties.

Additionally the plugin includes a custom converter itself which supports Map<String, String> class property types, since Grails supports this as a persistent class property type.

Defining Converter implementations

You can define a converter with Compass settings and (since 0.5.1) as Spring beans.

Compass settings

The Compass settings can either be defined in the plugin's configuration or in a native Compass configuration file.

In the plugin's config you might do:

Map compassSettings = [
    'compass.converter. funkyConverter.type': 'com.acme.compass.converter.FunkyConverter'
]

which registers a converter called "funkyConverter"@.

See the Compass settings for the complete range of options.

Spring beans

If you define a Spring bean in @resources.xml or resources.groovy that is an instance of org.compass.core.converter.Converter then it wil be automatically registered with Compass using the Spring bean name as it's name.

This allows you to inject your analyzer with other Spring beans and configuration, eg

import com.acme.compass.converter.MyHtmlConverter
beans = {
    htmlConverter(MyHtmlConverter) {
        context = someContext
        includeMeta = true
    }
}

defines a converter called @"htmlConverter"@.

Using Converters

Converters are defined in the class mapping, either at either at the class level

class Book {
    static searchable = {
        converter 'bookConverter'
    }
    String title
}

and/or at the property level

class Book {
    static searchable = {
        title converter: 'bookTitleConverter'
    }
    String title
}

Note you can also use native Compass XML or annotations to map with custom converters.