solr/solr-ref-guide/src/luke-request-handler.adoc

= Luke Request Handler
// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

The Luke Request Handler offers programmatic access to the information provided on the <<schema-browser-screen#schema-browser-screen,Schema Browser>> page of the Admin UI.
It is modeled after the Luke, the Lucene Index Browser by Andrzej Bialecki.  It is an implicit handler, so you don't need to define it.

The Luke Request Handler accepts the following parameters:

`show`::
The data about the index to include in the response.  Options are `schema`, `index`, `doc`, `all`.  `index` describes the high level details about the index.  `schema` returns details about the `schema` plus the `index` data.  `doc` works in conjunction with `docId` or `id` parameters and returns details about a specific document plus the `index` data.

`id`::
Get a document using the uniqueKeyField specified in schema.xml.

`docId`::
Get a document using a Lucene documentID.

`fl`::
Limit the returned values to a set of fields. This is useful if you want to increase the `numTerms` and don't want a massive response.

`numTerms`::
How many top terms for each field. The default is 10.

`includeIndexFieldFlags`::
Choose whether /luke should return the index-flags for each field. Fetching and returning the index-flags for each field in the index has non-zero cost, and can slow down requests to /luke.


== LukeRequestHandler Examples

The following examples assume you are running Solr's `techproducts` example configuration:

[source,bash]
----
bin/solr start -e techproducts
----

To return summary information about the index:

[source,text]
http://localhost:8983/solr/techproducts/admin/luke?numTerms=0

To return schema details about the index:

[source,text]
http://localhost:8983/solr/techproducts/admin/luke?show=schema

To drill into a specific field `manu`, then you drop the `show` parameter and add the `fl` parameter:

[source,text]
http://localhost:8983/solr/techproducts/admin/luke?fl=manu

To see the specifics of a document using the Solr uniqueKeyField field:

[source,text]
http://localhost:8983/solr/techproducts/admin/luke?fl=manu&id=TWINX2048-3200PRO

Alternatively, to work through the Lucene native id:

[source,text]
http://localhost:8983/solr/techproducts/admin/luke?fl=manu&docId=0

From SolrJ, you can access /luke using the {solr-javadocs}/solr-solrj/org/apache/solr/client/solrj/request/LukeRequest.html[`LukeRequest`] object.