How to use the snowball analyzer with NEST and ElasticSearch? - elasticsearch

Question

I am unclear: does the snowball analyzer have to be used when making the index?
var Client = new ElasticClient(Settings);
Client.CreateIndex("pictures", i => i
.Settings(st => st
.Analysis(a => a
.Analyzers(ad => ad
.Snowball("snowball", s => s.Language(SnowballLanguage.English))
)
)
)
);
or when doing the search?
var queryResults = Client.Search<PictureIndex>(s => s
.From(0).Size(10)
.Query(q=>q
.QueryString(qs=>qs
.Analyzer("snowball")
.Query("my test string")
)
)
);
This code doesn't return the expected results.
For example, if I have:
tomato, and
tomatoes
in my index, I'm expecting to find 2 results if I search for tomato, but it's not the case.
I'm trying to make an English only, case insensitive, stemmed search and add fuzziness to accommodate misspellings.
(As a bonus, I'd like to be able to submit a list of synonyms)
Edit:
this is the test code I have, but I think I misunderstand how to enter synonyms. The code will return no matches.
public static class Program
{
public class IndexData
{
public int Id { get; set; }
public string Text { get; set; }
}
public static void Main()
{
var Settings = new ConnectionSettings(new Uri("http://elasticsearch:9200")).DefaultIndex("testindex");
var A = new List<IndexData>
{
new IndexData { Id = 11, Text = "I like red, green and blue. But also cookies and candies" },
new IndexData { Id = 12, Text = "There is a red cookie on the shelf" },
new IndexData { Id = 13, Text = "Blue candies are my favorite" }
};
var Client = new ElasticClient(Settings);
var D = Client.DeleteIndexAsync("testindex").Result;
var U = Client.CreateIndex("testindex", i => i
.Settings(s => s
.Analysis(a => a
.CharFilters(cf => cf
.Mapping("my_char_filter", m => m
.Mappings("Blue => blue", "Red => red", "Green => green")
)
)
.TokenFilters(tf => tf
.Synonym("my_synonym", sf => sf
.Synonyms("red, blue")
.Synonyms("green, blue")
)
)
.Analyzers(an => an
.Custom("my_analyzer", ca => ca
.Tokenizer("standard")
.CharFilters("my_char_filter")
.Filters("lowercase", "stop", "my_synonym")
)
)
)
)
);
var R = Client.IndexDocument(A[0]);
R = Client.IndexDocument(A[1]);
R = Client.IndexDocument(A[2]);
var Articles = Client.Search<IndexData>(s => s
.From(0)
.Size(1000)
.Analyzer("my_analyzer")
.Query(q => q.Fuzzy(fz => fz.Field("text").Value("blue").MaxExpansions(2)))
);
var Documents = Articles.Documents;
}
}
What I am trying to achieve is a text search where:
I can have some minor misspellings
Handle plurals: tomato = tomatoes
I can define synonyms (for example here I'm expecting search for 'blue' to return also the 'red' and the 'green')
Get a sorted list of matches with best hits first. By best, I mean hits that cover more of the search terms.
I have to admit that, despite going over the docs, I am extremely confused by the terminology and the flow of the whole system. Another issue is that half of the samples on the web just don't compile because it looks like the API has changed at some point.