Return no result for NEST C# but Query DSL return result

Question

I have this Query DSL which return the correct result when I query directly at ElasticSearch

GET /person/_search
{
  "query": {
    "match": {
          "nameDetails.nameValue.firstName": {
            "query": "Fawsu"
          }
        }
    }
  }
}

But in NEST C#, it doesn't return any result. May I know what's wrong with my syntax?

        var response = _elasticClient.Search<Person> (s => s
            .Index("person")
            .Query(q => q
                .Match(m => m
                    .Field(f => f.NameDetails.Name.First().NameValue.FirstName)
                    .Query("Fawsu")
                )
            )
        );

or

        var response = _elasticClient.Search<Person> (s => s
            .Index("person")
            .Query(q => q
                .Match(m => m
                    .Field(f => f.NameDetails.Name[0].NameValue.FirstName)
                    .Query("Fawsu")
                )
            )
        );

How do I see the query generated by NEST to troubleshoot this?

Answer 1

The expression in .Field(f => f.NameDetails.Name[0].NameValue.FirstName) looks like it has an extra level, Name, to the object graph compared to the expected string. I would expect the output of the expression would be

nameDetails.name.nameValue.firstName

which will not match the field "nameDetails.nameValue.firstName" in the query.

You can see what NEST sends to Elasticsearch in a number of ways