Search for a specific query (TermsQuery) without type-specific class in NEST

Question

First time using ElasticSearch (using NEST as the wrapper). I want to search in an external ElasticSearch database.

I simply want to run a test query towards a specific field called cvrNummer. I have the following code, which doesn't compile because: The type arguments for method 'ElasticSearch.Search<T> .. ', cannot be inferred from the usage.

I assume it's because I cannot specify the type-specific class. Challenge is I don't know that one.

My question is: how do I run the query below, without exactly know what I get back (to make a type-specific model)? And if I need that model, how do I "make" that model when the documentation is lacking?

My code:

        var settings = new ConnectionSettings(new Uri(_path)).
        BasicAuthentication(_username,_password);

        var client = new ElasticClient(settings);

        var es_query = new TermsQuery
        {
            Name = "named_query",
            Boost = 1.1,
            Field = "cvrNummer",
            Terms = new string[] { "36406208" }
        };

        client.Search(es_query);

Only documentation I have:

curl -u "<brugernavn>:<password>" -XPOST http://URL -d'
{ "from" : 0, "size" : 1,
  "query": {
    "term": {
      "cvrNummer": VALUE
    }
  }
}

EDIT MORE DATA:

Document model from documentation:

curl -u "<brugernavn>:<password>" -XGET http://distribution.virk.dk/cvr-permanent/_mapping

Full search example:

curl -u "<brugernavn>:<password>" -XPOST http://distribution.virk.dk/cvr-permanent/_search -d'
{ "from" : 0, "size" : 1,
  "query": {
    "term": {
      "cvrNummer": 10961211
    }
  }
}
'

Try something like this: `client.Search(s => s.From(0).Size(1).Query(q => q.Terms(t => t.Name("named_query").Boost(1.1f).Field("cvrNummer").Terms("36406208"))));` — Evk, Mar 04 '18 at 11:50
@Evk Thanks! This results in a: "'Index name is null for the given type and no default index is set. Map an index name using ConnectionSettings.DefaultMappingFor() or set a default index using ConnectionSettings.DefaultIndex().'" . Any idea? :-) — Lars Holdgaard, Mar 04 '18 at 11:54
And how full url in curl "documentation" looks like (the path part, after domain)? — Evk, Mar 04 '18 at 12:01
Then try to `s => s.From(0).Size(1).Index("cvr-permanent").AllTypes().(... the rest of the above...)` — Evk, Mar 04 '18 at 12:06
@Evk Perfect - that works. I still get "Invalid NEST response built from a unsuccessful low level call on POST" but that's an error that makes sense (URL doesn't match). I will fix that one. Will you add a quick answer? Then I will mark it as the answer :-) — Lars Holdgaard, Mar 04 '18 at 12:10
Yep. Just got it to work by changing my original path to http://distribution.virk.dk/ without any parameters. Thanks a lot @Evk - solved my problem :-) ! — Lars Holdgaard, Mar 04 '18 at 12:16
Did you see the documentation at: https://www.elastic.co/guide/en/elasticsearch/client/net-api/current/index.html — Russ Cam, Mar 04 '18 at 17:34

Evk · Accepted Answer · 2018-03-04T12:31:54.683

You can convert your "documentation" curl request to C# api syntax like this:

client.Search<dynamic>(s => s //dynamic because you don't know the structure
    .From(0)
    .Size(1)
    .Index("cvr-permanent") // index you are searching, taken from url of curl
    .AllTypes() // search all types in that index
    .Query(q => q.Terms(t => 
         t.Name("named_query")
        .Boost(1.1f)
        .Field("cvrNummer")
        .Terms("36406208"))));

If you don't like dynamic - you can use JObject, which will be the real type returned by Search if you used dynamic:

var response = client.Search<JObject>(...);

Then you can access matched documents like this:

foreach (var document in result.Documents) {
    // if you used `JObject`:
    Console.WriteLine(document["account_number"]);
    // if you used `dynamic`:
    Console.WriteLine(document.account_number);
}

If you used JObject you can also call ToString() on the resulting JObject (so, document.ToString() in the example above) to see full json of returned document, so that you can learn its structure.

Search for a specific query (TermsQuery) without type-specific class in NEST

1 Answers1