Using the has_child query

Elasticsearch does not only support simple unrelated documents, it also lets you define a hierarchy based on our parent and children. The has_child query allows querying for parent documents of children matching other queries.

Getting ready

You need an up-and-running Elasticsearch installation as we described in the Downloading and installing Elasticsearch recipe in Chapter 2, Downloading and Setup.

To execute curl via the command line, you need to install curl for your operating system.

To correctly execute the following commands, you need an index populated with the chapter_07/populate_relations.sh script available in online code.

How to do it...

To execute the has_child queries, we will perform the following steps:

1. We want to search parents test-type of children test-type2 , which has a term in the field value as value1. We can create this kind of query:

           curl -XPOST 'http://127.0.0.1:9200/test-index/test-
           type/_search?pretty' -d '{
           ...