Make your Ruby objects searchable with Elasticsearch.
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README.md

estella

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Builds on elasticsearch-model to make your Ruby objects searchable with Elasticsearch. Provides fine-grained control of fields, analysis, filters, weightings and boosts.

Compatibility

This library is compatible with Elasticsearch 1.5.x, 2.x and currently does not work with Elasticsearch 5.x (see #18). It works with many ORM/ODMs, including ActiveRecord and Mongoid.

Dependencies

Installation

gem 'estella'

Estella will try to use Elasticsearch on localhost:9200 by default.

You can configure your global ElasticSearch client like so:

Elasticsearch::Model.client = Elasticsearch::Client.new host: 'foo.com', log: true

It's also configurable on a per-model basis. Refer to the ElasticSearch documentation for details.

Indexing

Include the Estella::Searchable module and add a searchable block in your model declaring the fields to be indexed.

class Artist < ActiveRecord::Base
  include Estella::Searchable

  searchable do
    field :name, type: :string, analysis: Estella::Analysis::FULLTEXT_ANALYSIS, factor: 1.0
    field :keywords, type: :string, analysis: ['snowball', 'shingle'], factor: 0.5
    field :bio, using: :biography, type: :string, index: :not_analyzed
    field :birth_date, type: :date
    field :follows, type: :integer
    field :published, type: :boolean, filter: true
    boost :follows, modifier: 'log1p', factor: 1E-3
  end
end

For a full list of the options available for field mappings, see the ElasticSearch mapping documentation.

The filter option allows the field to be used as a filter at search time.

You can optionally provide field weightings to be applied at search time using the factor option. These are multipliers.

Document-level boosts can be applied with the boost declaration, see the field_value_factor documentation for boost options.

While filter, boost and factor are query options, Estella allows for their static declaration in the searchable block for simplicity - they will be applied at query time by default when using #estella_search.

You can now create your index mappings with this migration:

Artist.reload_index!

This uses a default index naming scheme based on your model name, which you can override simply by declaring the following in your model:

index_name 'my_index_name'

Start indexing documents simply by creating or saving them:

Artist.create(name: 'Frank Estella', keywords: ['art', 'minimalism'])

Estella adds after_save and after_destroy callbacks for inline indexing, override these callbacks if you'd like to do your indexing in a background process. For example:

class Artist < ActiveRecord::Base
  include Estella::Searchable

  # disable estella inline callbacks
  skip_callback(:save, :after, :es_index)
  skip_callback(:destroy, :after, :es_delete)

  # declare your own
  after_save :delay_es_index
  after_destroy :delay_es_delete

  ...
end

A number of class methods are available for indexing.

# return true if the index exists
Artist.index_exists?

# create the index
Artist.create_index!

# delete and re-create the index without reindexing data
Artist.reload_index!

# recreate the index and reindex all data
Artist.recreate_index!

# delete the index
Artist.delete_index!

# commit any outstanding writes
Artist.refresh_index!

Custom Analysis

Estella defines standard, snowball, ngram and shingle analyzers by default. These cover most search contexts, including auto-suggest. In order to enable full-text search for a field, use:

analysis: Estella::Analysis::FULLTEXT_ANALYSIS

Or alternatively select your analysis by listing the analyzers you want enabled for a given field:

field :keywords, type: :string, analysis: ['snowball', 'shingle']

Estella default analyzer and sharding options are defined here and can be customized by passing a settings hash to the searchable block.

my_analysis = {
  tokenizer: {
    ...
  },
  filter: {
    ...
  }
}

my_settings = {
  analysis: my_analysis,
  index: {
    number_of_shards: 1,
    number_of_replicas: 1
  }
}

searchable my_settings do
  ...
end

See configuring analyzers for more information.

Searching

Perform full-text search with estella_search:

Artist.estella_search(term: 'frank')
Artist.estella_search(term: 'minimalism')

Estella searches all analyzed text fields by default, using a multi_match search. The search will return an array of database records, ordered by score. If you'd like access to the raw Elasticsearch response data use the raw option:

Artist.estella_search(term: 'frank', raw: true)

Estella supports filtering on filter fields and pagination:

Artist.estella_search(term: 'frank', published: true)
Artist.estella_search(term: 'frank', size: 10, from: 5)

You can exclude records:

Artist.estella_search(term: 'frank', exclude: { keywords: 'sinatra' })

If you'd like to customize your term query further, you can extend Estella::Query and override query_definition and field_factors:

class MyQuery < Estella::Query
  def query_definition
    {
      multi_match: {
        ...
      }
    }
  end

  def field_factors
    {
      default: 5,
      ngram: 5,
      snowball: 2,
      shingle: 1,
      search: 1
    }
  end
end

Or manipulate the query for all cases (with or without term) in the initializer directly via query or by using built-in helpers must and exclude.

class MyQuery < Estella::Query
  def initialize(params)
    super
    # same as query[:filter][:bool][:must] = { keywords: 'frank' }
    must(term: { keywords: 'frank' })
    # same as query[:filter][:bool][:must_not] = { keywords: 'sinatra' }
    exclude(term: { keywords: 'sinatra' })
  end
end

And then override class method estella_search_query to direct Estella to use your query object:

class Artist < ActiveRecord::Base
  include Estella::Searchable

  searchable do
    ...
  end

  def self.estella_search_query
    MyQuery
  end
end

Artist.estella_search(term: 'frank')

For further search customization, see the ElasticSearch DSL.

Contributing

See CONTRIBUTING.

License

MIT License. See LICENSE.