NEST Elasticsearch advanced sorting

Question

I have a lot of animal documents and I want to sort the items, that the cats should result first, the other animals afterwards.

My approach

var client = new Nest.ElasticClient(settings);
client.Search<Animals>(s => s.MatchAll().Sort(y => y.Descending(d => d.Type == "cat"))); 

But it doesn't give the desired result.

Answer 1

For this you need to use script sorting

If you want the field in source with name type. You can't get a value of a text field but this will work for keyword field

   var items =  db.Search<Animals>(s => s.
                   Index("test").
                   Type("").
                   Sort(sort => sort.
                                Script(sd => sd.
                                             Type("number").
                                             Script(sdd => sdd.
                                                           Inline("doc['type.keyword'].value == 'cat' ? 0 : 1")).
                                                           Ascending())));

If you want the index type of the source. Note I would not recommend using this for new apps since they will remove this in ES6

var items2 = db.Search<Animals>(s => s.
                Index("test").
                Type("").
                Sort(sort => sort.
                             Script(sd => sd.
                                          Type("number").
                                          Script(sdd => sdd.
                                                        Inline("doc['_type'].value == 'cat' ? 0 : 1")).
                                                        Ascending())));