pombredanne / luces

A library to convert Lucene documents to JSON

Luces

A library to convert Lucene documents to JSON for Elasticsearch consumption

License: Apache 2.0

Dependencies:

• Java 8
• gson 2.3.1
• lucene-core 3.6.1
• junit 3.8.1
• slf4j 1.7.5

Usage:

The library can be used like so:

Luces lucesConverter = new Luces(org.apache.lucene.util.Version.LUCENE_36)
JsonElement jsonDoc = lucesConverter.documentToJSON(Document doc);

Where doc is a populated Lucene document. A JsonObject will be returned that can be sent to Elasticsearch. For testing purposes, you can also pass a boolean to pretty print the output:

String jsonBlob = lucesConverter.documentToJSONStringified(Document doc, true);

You can also specify an elasticsearch mapping JSON blob, which will enable any string values that are supposed to be integers, floats, etc. into their correct types For example, a mapping like:

{
  "user": {
    "properties": {
      "name": {
        "type": "string"
      },
      "id": {
        "type": "integer"
      }
    }
  }
}

can be added to the converter this way, as a JsonObject:

lucesConverter.mapping("user", mappingJsonObject)

where "user" is the type in Elasticsearch.

When using a mapping file, empty values will not be parsed correctly, so you can specify if you want empty values replaced with the defaults for the type:

lucesConverter.useDefaultsForEmpty(true);

Otherwise, it defaults to false, and will throw a NumberFormatException when a value is empty. Keep in mind that invalid values (like 123abc in an integer field) will still throw parsing errors regardless of the flag

##Options:

lucesConverter.useDefaultsForEmpty(bool);

If true, uses the default value for a primitive if the string is empty (0, 0.0, false). Setting to true will set useNullForEmpty to false

lucesConverter.useNullForEmpty(bool);

If true, uses null for an empty string value. Setting to true will set useDefaultsForEmpty to false.

lucesConverter.throwErrorIfMappingIsNull(bool);

Throws an error if the mapping is set to null, or if trying to convert a document without specifying a type and mapping. Defaults to true

TODO:

• Handle mappings with hierarchical levels to type determination