ElasticSearch：在搜索结果中包含内部对象

Question

I've a elastic search index containing elements taht have nested subelements as properties, eg.

{
    _index: tests,
    _type: test,
    _id: 11021,
    _version: 1,
    _score: 1,
    _source: {
        id: 11021,
        name: "demotest",
        responsiblePerson: {
            userId: "221",
            userName: "Walter",
            userSurName: "White",
            userEmail: "Walter.White@lospollos.com"
        },      
       listOfSubItems: [{"name": "location"},{"name":"sample"},{"name":"experiment"}]
    }
}

Now, I'd like to include some fields of that explicitly in the result of a query (eg to exclude the listOfSubitems from the result to reduce it's size; that's also the reason why i don't want to fall back onto the _source attribute).

The code for the java API would be:

 SearchResponse responseTests = client.prepareSearch("tests")
                    .addField("id")
                    .addField("name")
                    .addField("responsiblePerson") 
                    .setQuery(QueryBuilders.matchQuery("id", testId))
                    .execute()
                    .actionGet();

SearchHits testHits = responseTests.getHits();

Unfortunately, this query doesn't work for some reason as testHits.getTotalHits() shows a number but testHits.getHits().length is 0 :-(

Does someone have a hint for me how i can get this to work?

Answer 1

"The reason why you can't get the stored field values for a nested object is because it is stored in a separate Lucene document.

If nested is enabled in the mapping a single ES document is stored as separate Lucene documents. Each nested object will be a single Lucene document. Also the main / root document will be a separate Lucene document. ES will always translates matches back to the root Lucene document. The _source is always associated with the root Lucene document. When fields are being fetched the translation to Lucene root document already has taken place, so accessing the nested stored fields isn't possible, but accessing the values from the _source will work.

I don't think this is a bug, but rather an limitation of how ES currently works with nested docs. Once #3022 has been implemented, accessing the stored fields of nested Lucene docs is possible."

you can find it here https://github.com/elasticsearch/elasticsearch/issues/5245