4.6. Bridges
When mapping entities, Lucene represents all index fields as strings. All entity properties annotated with
@Field are converted to strings to be indexed. Built-in bridges automatically translates properties for the Lucene-based Query API. The bridges can be customized to gain control over the translation process.
4.6.1. Built-in Bridges
The Lucene-based Query API includes a set of built-in bridges between a Java property type and its full text representation.
- null
- Per default
nullelements are not indexed. Lucene does not support null elements. However, in some situation it can be useful to insert a custom token representing thenullvalue. See Section 4.1.2, “@Field” for more information. - java.lang.String
- Strings are indexed, as are:
short,Shortinteger,Integerlong,Longfloat,Floatdouble,DoubleBigIntegerBigDecimal
Numbers are converted into their string representation. Note that numbers cannot be compared by Lucene, or used in ranged queries out of the box, and must be paddedNote
Using a Range query has disadvantages. An alternative approach is to use a Filter query which will filter the result query to the appropriate range.The Query Module supports using a customStringBridge. See Section 4.6.2, “Custom Bridges”. - java.util.Date
- Dates are stored as yyyyMMddHHmmssSSS in GMT time (200611072203012 for Nov 7th of 2006 4:03PM and 12ms EST). When using a
TermRangeQuery, dates are expressed in GMT.@DateBridgedefines the appropriate resolution to store in the index, for example:@DateBridge(resolution=Resolution.DAY). The date pattern will then be truncated accordingly.@Indexed public class Meeting { @Field(analyze=Analyze.NO) @DateBridge(resolution=Resolution.MINUTE) private Date date; ...The defaultDatebridge uses Lucene'sDateToolsto convert from and toString. All dates are expressed in GMT time. Implement a custom date bridge in order to store dates in a fixed time zone. - java.net.URI, java.net.URL
- URI and URL are converted to their string representation
- java.lang.Class
- Class are converted to their fully qualified class name. The thread context classloader is used when the class is rehydrated
