Session: How to Use MoreLikeThis

MoreLikeThis is available through query extension methods and will return similar documents according to the provided criteria and options.

Syntax

IRavenQueryable<T> MoreLikeThis<T>(MoreLikeThisBase moreLikeThis);

IRavenQueryable<T> MoreLikeThis<T>(Action<IMoreLikeThisBuilder<T>> builder);

Builder

IMoreLikeThisOperations<T> UsingAnyDocument();

IMoreLikeThisOperations<T> UsingDocument(string documentJson);

IMoreLikeThisOperations<T> UsingDocument(Expression<Func<T, bool>> predicate);

IMoreLikeThisOperations<T> WithOptions(MoreLikeThisOptions options);

Options

public int? MinimumTermFrequency { get; set; } = 2;

public int? MaximumQueryTerms { get; set; } = 25;

public int? MaximumNumberOfTokensParsed { get; set; } = 5000;

public int? MinimumWordLength { get; set; } = 0;

public int? MaximumWordLength { get; set; } = 0;

public int? MinimumDocumentFrequency { get; set; } = 5;

public int? MaximumDocumentFrequency { get; set; } = int.MaxValue;

public int? MaximumDocumentFrequencyPercentage { get; set; }

public bool? Boost { get; set; } = false;

public float? BoostFactor { get; set; } = 1;

public string StopWordsDocumentId { get; set; }

public string[] Fields { get; set; }

Example I

// Search for similar articles to 'articles/1'
// using 'Articles/MoreLikeThis' index and search only field 'Body'
List<Article> articles = session
    .Query<Article>("Articles/MoreLikeThis")
    .MoreLikeThis(builder => builder
        .UsingDocument(x => x.Id == "articles/1")
        .WithOptions(new MoreLikeThisOptions
        {
            Fields = new[] { "Body" }
        }))
    .ToList();

// Search for similar articles to 'articles/1'
// using 'Articles/MoreLikeThis' index and search only field 'Body'
List<Article> articles = await asyncSession
    .Query<Article>("Articles/MoreLikeThis")
    .MoreLikeThis(builder => builder
        .UsingDocument(x => x.Id == "articles/1")
        .WithOptions(new MoreLikeThisOptions
        {
            Fields = new[] { "Body" }
        }))
    .ToListAsync();

from index 'Articles/MoreLikeThis' 
where morelikethis(id() = 'articles/1', '{ "Fields" : [ "Body" ] }')

Example II

// Search for similar articles to 'articles/1'
// using 'Articles/MoreLikeThis' index and search only field 'Body'
// where article category is 'IT'
List<Article> articles = session
    .Query<Article>("Articles/MoreLikeThis")
    .MoreLikeThis(builder => builder
        .UsingDocument(x => x.Id == "articles/1")
        .WithOptions(new MoreLikeThisOptions
        {
            Fields = new[] { "Body" }
        }))
    .Where(x => x.Category == "IT")
    .ToList();

// Search for similar articles to 'articles/1'
// using 'Articles/MoreLikeThis' index and search only field 'Body'
// where article category is 'IT'
List<Article> articles = await asyncSession
    .Query<Article>("Articles/MoreLikeThis")
    .MoreLikeThis(builder => builder
        .UsingDocument(x => x.Id == "articles/1")
        .WithOptions(new MoreLikeThisOptions
        {
            Fields = new[] { "Body" }
        }))
    .Where(x => x.Category == "IT")
    .ToListAsync();

from index 'Articles/MoreLikeThis' 
where morelikethis(id() = 'articles/1', '{ "Fields" : [ "Body" ] }') and Category == 'IT'

Remarks

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

using Raven.Client.Documents;