Boolean and "conditionless" queries

[andersosthus]

Hi,

Been trying out NEST 2.0.0-Alpha 1 and I think there are some changes that could be important do document. If you try to add something to a boolean that's not "complete", it's not added. This is a bit different to the NEST 1.x behaviour.

Example:

var oldNest = new SearchDescriptor<TestObject>()
    .Index("index")
    .Type("type")
    .Query(q => q
        .Bool(b => b
            .Must(m => m.MatchAll())
            .Should(s => s
                .Fuzzy(f => f
                    .Field("name")
                    .Value("testvalue")))));

Produces in NEST 1.7.1:

{
  "query": {
    "bool": {
      "must": [
        {
          "match_all": {}
        }
      ],
      "should": [
        {
          "fuzzy": {
            "name": {
              "value": "testvalue"
            }
          }
        }
      ]
    }
  }
}

But in NEST 2.0.0 Alpha 1, it produces:

{
  "query": {
    "bool": {
      "must": [
        {
          "match_all": {}
        }
      ]
    }
  }
}

If you then change it to be the following:

var newNest = new SearchDescriptor<TestObject>()
    .Index("index")
    .Type("type")
    .Query(q => q
        .Bool(b => b
            .Must(m => m.MatchAll())
            .Should(s => s
                .Fuzzy(f => f
                    .Field("name")
                    .Value("testvalue")
                    .Fuzziness(Fuzziness.Auto)))));

it produces the expected output in NEST 2.0.0 Alpha 1:

{
  "query": {
    "bool": {
      "must": [
        {
          "match_all": {}
        }
      ],
      "should": [
        {
          "fuzzy": {
            "name": {
              "value": "testvalue",
              "fuzziness": "AUTO"
            }
          }
        }
      ]
    }
  }
}

This seems to apply to QueryStringas well (the DefaultField must be set). I have not checked any of the other queries.

[gmarz]

This looks like a bug actually. The conditionless behavior is kicking in because fuzziness isn't set (https://github.com/elastic/elasticsearch-net/blob/master/src/Nest/QueryDsl/TermLevel/Fuzzy/FuzzyQueryBase.cs#L33), but fuzziness is an optional parameter.

We may need to re-validate all of the IsConditionless states for the next release.