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elasticsearchHow can I use Elasticsearch with C#?

Elasticsearch can be used with C# via the official low-level client library NEST.

NEST provides a strongly-typed query DSL that maps 1:1 with the Elasticsearch query DSL, and takes advantage of specific C# features such as covariant results and auto mapping of POCO types.

Example code to connect to an Elasticsearch cluster, index a document, and search for it:

var defaultIndex = "my-index";

var settings = new ConnectionSettings(new Uri("http://localhost:9200"))

var client = new ElasticClient(settings);

// Index a document
var person = new Person { Id = 1, Name = "Martijn Laarman" };
var indexResponse = client.IndexDocument(person);

// Search for the document
var searchResponse = client.Search<Person>(s => s
    .Query(q => q
        .Term(f => f.Name, person.Name)

// Output the total number of documents found
Console.WriteLine($"{searchResponse.Total} documents found");

Output example

1 documents found

The code above does the following:

  1. Creates a ConnectionSettings object, which specifies the connection parameters to the Elasticsearch cluster.
  2. Creates an ElasticClient object, using the ConnectionSettings.
  3. Indexes a Person object, which is a custom POCO type.
  4. Searches for the document using a Term query on the Name field.
  5. Outputs the total number of documents found.

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