Get raw query from NEST client

For NEST / Elasticsearch.NET v6.0.2, use the ApiCall property of the IResponse object. You can write a handy extension method like this:

public static string ToJson(this IResponse response)
{
    return Encoding.UTF8.GetString(response.ApiCall.RequestBodyInBytes);
}

Or, if you want to log all requests made to Elastic, you can intercept responses with the connection object:

var node = new Uri("https://localhost:9200");
var pool = new SingleNodeConnectionPool(node);
var connectionSettings = new ConnectionSettings(pool, new HttpConnection());
connectionSettings.OnRequestCompleted(call =>
{
    Debug.Write(Encoding.UTF8.GetString(call.RequestBodyInBytes));
});

You can get raw query json from RequestInformation:

var rawQuery = Encoding.UTF8.GetString(result.RequestInformation.Request);

Or enable trace on your ConnectionSettings object, so NEST will print every request to trace output

var connectionSettings = new ConnectionSettings(new Uri(elasticsearchUrl));
connectionSettings.EnableTrace(true);
var client = new ElasticClient(connectionSettings); 

NEST 7.x

Enable debug mode when creating settings for a client:

var settings = new ConnectionSettings(connectionPool)
    .DefaultIndex("index_name")
    .EnableDebugMode()
var client = new ElasticClient(settings); 

then your response.DebugInformation will contain information about request sent to elasticsearch and response from elasticsearch. Docs.

The methods to do this seem to change with each major version, hence the confusing number of answers. If you want this to work in NEST 6.x, AND you want to see the deserialized request BEFORE it's actually sent, it's fairly easy:

var json = elasticClient.RequestResponseSerializer.SerializeToString(request);

If you're debugging in Visual Studio, it's handy to put a breakpoint right after this line, and when you hit it, hover over the json variable above and hit the magnifying glass thingy. You'll get a nice formatted view of the JSON.