ElasticRecord
<img src=“https://secure.travis-ci.org/matthuhiggins/elastic_record.png?rvm=1.9.3” />
ElasticRecord is an elasticsearch ORM.
Setup
The usual Gemfile addition:
gem 'elastic_record'
Creating the index:
rake index:create
Include ElasticRecord into your model:
ActiveSupport.on_load :active_record do
include ElasticRecord::Model
end
Searching
ElasticRecord adds the method ‘elastic_search’ to your models. It works similar to active_record scoping:
search = Product.elastic_search
Filtering
If a simple hash is passed into filter, a term or terms query is created:
search.filter(color: 'red') # Creates a term filter
search.filter(color: %w(red blue)) # Creates a terms filter
If a hash containing hashes is passed into filter, it is used directly as a filter DSL expression:
search.filter(prefix: { name: "Sca" }) # Creates a prefix filter
An Arelastic object can also be passed in, working similarily to Arel:
# Name starts with 'Sca'
search.filter(Product.arelastic[:name].prefix("Sca"))
# Name does not start with 'Sca'
search.filter(Product.arelastic[:name].prefix("Sca").negated)
# Size is greater than 5
search.filter(Product.arelastic[:size].gt(5))
# Product has no name
search.filter(Product.arelastic[:name].blank)
# Product has name
search.filter(Product.arelastic[:name].present)
# Name is 'hola' or name is blank
search.filter(Product.arelastic[:name].eq("hola").or(Product.arelastic[:name].blank))
Helpful Arel builders can be found at github.com/matthuhiggins/arelastic/blob/master/lib/arelastic/builders/filter.rb.
Lastly, negation is made easy with negate:
# Status is not active
search.negate(status: 'active')
Querying
To create a query string, pass a string to search.query:
search.query("red AND fun*") # Creates {query_string: {"red AND fun*"}}
Complex queries are done using either a hash or an arelastic object:
search.query(match: {description: "amazing"})
Ordering
search.order(:price) # sort by price
search.order(:color, :price) # sort by color, then price
search.order(price: :desc) # sort by price in descending order
Offsets and Limits
To change the ‘size’ and ‘from’ values of a query, use offset and limit:
search.limit(10).offset(20) # Creates a query with {size: 10, from: 20}
Facets
Since term facets are the most common, they are the easiest to add to a query:
search.facet('colors')
It is important to note that adding facets to a query is different than retrieving the results of the query:
search = search.facet('colors').facet('size')
search.facets
#=> {"colors" => ..., "size" => ...}
Getting Results
A search object behaves similar to an active_record scope, implementing a few methods of its own and delegating the rest to Array, and your class.
search.count # Return the number of search results
search.first # Limit results to 1 and return the first result or nil
search.find(id) # Add an ids filter to the existing query
search.as_elastic # Return the json hash that will be sent to elastic search.
The search object behaves like an array when necessary:
search.each do |product|
...
end
Class methods can be executed within scopes:
class Product
def self.increase_prices
all.each do { |product| product.increment(:price, 10) }
end
end
# Increase the price of all red products by $10.
Product.filter(color: 'red').increase_prices