Elasticsearch.net NEST Bool Query not generating expected request

Question

I'm attempting to create an Elasticsearch query in NEST which uses the Bool query, but everything I put inside the Bool method seems to get ignored.

This is the code I've tried:

var query = "my query";
var fileType = "Poster";
var searchResults = _client.Search<Doc>(s => 
        s.Query(q =>
            q.Bool(
                b => b.Must(
                    m =>  m.MatchPhrase(mp =>
                        mp.Query(query).Fuzziness(2))
                    ).Must(m => m.Match(
                        mp => mp.Query(fileType))))
            ).Highlight(x =>
                    x.OnFields(y =>
                        y.OnField(f => f.File)
                         .PreTags("<strong>")
                         .PostTags("</strong>"))
            ).Fields("fileType", "title"));

Here is the JSON request NEST is generating from that code. Notice that it's missing the entire query property:

{
  "highlight": {
    "fields": {
      "file": {
        "pre_tags": [
          "<strong>"
        ],
        "post_tags": [
          "</strong>"
        ]
      }
    }
  },
  "fields": [
    "fileType",
    "title"
  ]
}

I tried taking out the extra highlighting and field selection, in case that was causing a problem, just leaving the Query and the Bool:

var searchResults = _client.Search<Doc>(s => 
        s.Query(q =>
            q.Bool(
                b => b.Must(
                    m =>  m.MatchPhrase(mp =>
                        mp.Query(query).Fuzziness(2))
                    )
                .Must(m => m.Match(mp => mp.Query(fileType))))
            ));

This code generates an empty JSON object.

I couldn't find mention of the Bool and Must methods in the NEST documentation and I haven't been able to figure it out with trial and error.

What am I doing wrong?

Notes

I have used NEST's Query method with a simple QueryString. It generated the expected JSON request, so I'm pretty sure the way I have things configured is correct.

This is the JSON query that I'm attempting to recreate with NEST:

{
  "fields": [
    "title",
    "fileType"
  ],
  "query": {
    "bool": {
      "must": [
        {
          "match": {
            "fileType": {
              "query": "Poster"
            }
          }
        },
        {
          "match_phrase": {
            "file": {
              "query": "my query",
              "fuzziness": 2
            }
          }
        }
      ]
    }
  },
  "highlight": {
    "fields": {
      "file": {}
    }
  }
}

Rob · Accepted Answer · 2017-04-26T16:30:28.000

Your queries are missing .OnField(f => f.YourField). NEST ignores such queries because of conditionless.

I hope it's clear right now.

update

You should change your query to something like this:

var searchResults = client.Search<Doc>(s => s
    .Query(q => q
        .Bool(b => b
            .Must(
                m => m.Match(mp => mp.OnField(f => f.YourField).Query(fileType)),
                m => m.MatchPhrase(mp => mp.OnField(f => f.YourField).Query(query).Fuzziness(2)))
                ))
    .Highlight(x => x
        .OnFields(y => y
            .OnField(f => f.File)
            .PreTags("<strong>")
            .PostTags("</strong>")))
    .Fields("fileType", "title"));

You should use .Must(..) only once in bool query, otherwise you will replace previous .Must(..) definition. Fortunately you can pass multiple queries into the .Must(..) method.

Thanks, it's working for the Match clause, but MatchPhrase is still being ignored (even when I use it by itself). Any idea why that might be? — Sam, Aug 13 '15 at 16:47
I would just like to add that in 6.x version you must use Field method instead of OnField in the Match clause. — BineG, May 23 '18 at 10:38

Elasticsearch.net NEST Bool Query not generating expected request

Notes

1 Answers1