NEST Conditional filter query with multiple terms

Question

I would like to do a ElasticSearch query like this:

{
    "query" :
    {
        "bool" :
        {
            "filter" : [
                {
                    "terms" :
                    {
                        "name" : ["name1", "name2"]
                    }
                },
                {
                    "terms" :
                    {
                        "color" : ["orange", "red"]
                    }
                }
            ]
        }
    }
}

I've tried to implement it in NEST like this:

_elasticClient
    .SearchAsync<MyDocument>(s =>
        s.Index("myindex")
            .Query(q => q
                .Bool(bq => bq
                    .Filter(fq =>
                    {
                        QueryContainer query = null;

                        if (nameList.Any()) {
                            query &= fq.Terms(t => t.Field(f => f.Name).Terms(nameList));
                        }

                        if (colorList.Any()) {
                            query &= fq.Terms(t => t.Field(f => f.Color).Terms(colorList));
                        }

                        return query;
                    })
                )
            )
    );

But that gives me a query like this where the filters are wrapped inside a bool must:

{
    "query" :
    {
        "bool" :
        {
            "filter" : [
                {
                    "bool" :
                    {
                        "must" : [
                            {
                                "terms" :
                                {
                                    "name" : ["name1", "name2"]
                                }
                            },
                            {
                                "terms" :
                                {
                                    "color" : ["orange", "red"]
                                }
                            }
                        ]
                    }
                }
            ]
        }
    }
}

How should I change my NEST code to give me the right query? Do have have to add my terms to something other then a QueryContainer?

Adam Łepkowski · Accepted Answer · 2016-06-08 16:52:02Z

You can create a list of filters before you make a query if you want to check conditional filters as shown below:

var nameList = new[] {"a", "b"};
var colorList = new[] {1, 2};

var filters = new List<Func<QueryContainerDescriptor<MyDocument>, QueryContainer>>();
if (nameList.Any())
{
     filters.Add(fq=> fq.Terms(t => t.Field(f => f.Name).Terms(nameList)));
}

if (colorList.Any())
{
    filters.Add(fq => fq.Terms(t => t.Field(f => f.Color).Terms(colorList)));
}

ISearchResponse<Property> searchResponse =
     elasticClient.Search<MyDocument>(x => x.Query(q => q
     .Bool(bq => bq.Filter(filters))));

If you don't need to check any condition before making filter query then you can have something like that:

ISearchResponse<MyDocument> searchResponse =
elasticClient.Search<MyDocument>(x => x.Query(q => q
.Bool(bq => bq
.Filter(
        fq => fq.Terms(t => t.Field(f => f.Name).Terms(nameList)),
        fq => fq.Terms(t => t.Field(f => f.Color).Terms(colorList))
        ))));

Russ Cam · Accepted Answer · 2016-06-09 00:04:43Z

The Filter method of a bool query takes a params Func<QueryContainerDescriptor<T>, QueryContainer>[] so that you can pass it multiple expressions to represent multiple filters

var nameList = new string[] { "name1", "name2" };
var colorList = new string[] { "orange", "red" };

client.SearchAsync<MyDocument>(s => s
        .Index("myindex")
        .Query(q => q
            .Bool(bq => bq
                .Filter(
                    fq => fq.Terms(t => t.Field(f => f.Name).Terms(nameList)),
                    fq => fq.Terms(t => t.Field(f => f.Color).Terms(colorList))
                )
            )
        )
);

which results in

{
  "query": {
    "bool": {
      "filter": [
        {
          "terms": {
            "name": [
              "name1",
              "name2"
            ]
          }
        },
        {
          "terms": {
            "color": [
              "orange",
              "red"
            ]
          }
        }
      ]
    }
  }
}

NEST also has the concept of conditionless queries, that is, if a query is determined to be conditionless, then it will not be serialized as part of the request.

What does it mean to be conditionless? Well, that depends on the query; for example, in the case of a terms query it is deemed to be conditionless if any of the following are true

the field doesn't have a value
the term values list is null
the terms value is an empty collection
the terms values list has values but they are all null or empty strings

To demonstrate

var emptyNames = new string[] {};
string[] nullColors = null;

client.SearchAsync<MyDocument>(s =>
s.Index("myindex")
    .Query(q => q
        .Bool(bq => bq
            .Filter(
                fq => fq.Terms(t => t.Field(f => f.Name).Terms(emptyNames)),
                fq => fq.Terms(t => t.Field(f => f.Color).Terms(nullColors)))
        )
    )
);

results in

{}

Conditionless queries serve to make writing NEST queries easier in that you don't need to check if the collection has values before constructing a query. You can change conditionless semantics on a per query basis using .Strict() and .Verbatim().

Suraj Rao · Accepted Answer · 2018-12-05 10:40:08Z

var searchResponse = client.Search<EventData>(s => s
            .From(0)
            .Query(q => q
                    .Bool(bq => bq
                    .Filter(
                            fq => fq.Terms(t => t.Field(f => f.Client.Id).Terms(17)),
                            fq => fq.Terms(t => t.Field(f => f.Item.Id).Terms(**new[] { 34983, 35430, 35339, 35300 }**)), 
                            fq => fq.Terms(t=>t.Field(f=>f.Event).Terms("Control de Panico")),
                            fq => fq.DateRange(dr => dr.Field(f => f.DateTime)
                                .GreaterThanOrEquals(new DateTime(2018, 07, 01))
                                .LessThanOrEquals(new DateTime(2018, 10, 02)))
                            )
                  ))
            .Size(2000)
            .Sort(g => sortDescriptor)
            );

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