ElasticSearch: Querying a field that's an array of objects

Question

I've got data indexed using ElasticSearch, and I'm having trouble querying a particular field. A snippet of the JSON is as follows:

 {
 "_index": "indexName",
 "_type": "type",
 "_id": "00001",
 "color": "red",
 "place": "london",
 "person": [
      {
           "name": "john",
           "friends": [
               "mary",
               "jane"
           ]
      }
      {
           "name": "jack",
           "friends": [
               "lisa",
               "alex"
           ]
      }

 ]
 }

I need to query the index and pick out all records where one of the names inside person is "john".

I'm using Client.Search to do this, and I've had no trouble querying the fields that aren't nested (like color) by using:

 var searchResults = client.Search<People>(s => s
            .Index("indexName")
            .Type("type")
            .Query(q => q
                .Bool(b => b
                    .Must(
                        x => x.Match(m => m.OnField(p => p.color).Query("red")),
                        x => x.Match(m => m.OnField(p => p.place).Query("london"))))));

I've got People defined as follows:

public class People
{
    public string color {get; set; }
    public string place {get; set; }
    public List<Person> person {get; set; }
}
public class Person
{
    public string name {get; set; }
    // "friends" isn't here as I don't pull data from it
}

I'm unsure as to how to query on name as it's "inside" people - any help is greatly appreciated.

Answer 1

You need to wrap query in nested_query to have access to nested fields.

{
    "nested" : {
        "path" : "person",
        "query" : {
             "match" : {"person.name" : "john"}
        }
    }
}

Exceprt from documentation:

The query is executed against the nested objects / docs as if they were indexed as separate docs (they are, internally) and resulting in the root parent doc (or parent nested mapping).

Basically internally nested fields are stored as separate documents nearby (so they are quick to fetch) the original document. By default elastic doesn't load them, so you need to explicitly tell him that you want to access it. You could say nested fields are lazy ;)

Sorry It's been a long time since I worked on .Net and Linq. Don't know the API. But you need to create something like that.

Edit. From github source and your code I think you need to:

var s = new SearchDescriptor<People>()
                .Query(ff=>ff
                    .Nested(n=>n
                        .Path(f=>f.person[0])
                        .Query(q=>q.Term(f=>f.person[0].name,"john"))
                    )
                );

Edit2. Did you try direct curl to server? Or try query in head plugin? Something like:

curl -XPOST 'http://localhost:9202/indexName' -d '
{
  "query": {
    "nested": {
      "path": "person",
      "query": {
        "query_string": {
          "query": "person.name: john"
        }
      }
    }
  }
}'

This works on my cluster (with changed column names).

Answer 2

After a long while, I finally figured out that my data wasn't actually indexed as nested in the first place, and so simply adding

.Term("person.name", "john")

to my query worked perfectly.