see on GitHub

Session : How to use MoreLikeThis?

MoreLikeThis is available through extension method in Advanced session operations. This method returns articles similar to the provided input.

Syntax

TResult[] MoreLikeThis<TResult, TIndexCreator>(
	this ISyncAdvancedSessionOperation advancedSession,
	MoreLikeThisQuery parameters) 
	where TIndexCreator : AbstractIndexCreationTask, new() { ... }

TResult[] MoreLikeThis<TResult>(
	this ISyncAdvancedSessionOperation advancedSession,
	string index,
	string documentId) { ... }

TResult[] MoreLikeThis<TTransformer, TResult, TIndexCreator>(
	this ISyncAdvancedSessionOperation advancedSession,
	string documentId)
	where TIndexCreator : AbstractIndexCreationTask, new()
	where TTransformer : AbstractTransformerCreationTask, new() { ... }

Parameters
index string Name of an index on which query will be executed.
documentId string Id of a document for which similarities will be searched.
parameters MoreLikeThisQuery A more like this query definition that will be executed.
Return Value
TResult[] Array of similar documents returned as entities.

Example I

// Search for similar articles to 'articles/1'
// using 'Articles/MoreLikeThis' index and search only field 'Body'
Article[] articles = session
	.Advanced
	.MoreLikeThis<Article>(
		"Articles/MoreLikeThis",
		null,
		new MoreLikeThisQuery
		{
			IndexName = "Articles/MoreLikeThis", 
			DocumentId = "articles/1", 
			Fields = new[] { "Body" }
		});

Example II

// Search for similar articles to 'articles/1'
// using 'Articles/MoreLikeThis' index and search only field 'Body'
// where article category is 'IT'
Article[] articles = session
	.Advanced
	.MoreLikeThis<Article>(
		"Articles/MoreLikeThis",
		null,
		new MoreLikeThisQuery
		{
			IndexName = "Articles/MoreLikeThis",
			DocumentId = "articles/1",
			Fields = new[] { "Body" },
			AdditionalQuery = "Category:IT"
		});

Remarks

Do not forget to add following using statement which contains necessary extensions:

using Raven.Abstractions.Data;
using Raven.Client.Bundles.MoreLikeThis;
using Raven.Client.Document;