Smart Segments

This is the official documentation of the agent_ruby Ruby agent.

Smart Segments should be quick to migrate, as the syntax is very similar to the legacy agent.

You can find the full documentation of segment customization here.

How to migrate

Structure

Because the new Forest Admin agent is designed to work with multiple databases, the return value of the filter function is not a Sequelize or Mongoose condition anymore.

Instead, you'll be building a condition tree that will be translated to the appropriate database syntax by the agent.

Performance

All queries cannot be expressed in the Forest Admin query interface, but many can.

You can have great performance improvements by using the Forest Admin query interface to build your conditions, instead of performing the query yourself, and then building a naive condition tree, which filters by primary key like in the example we're providing.

Example

In this example, we migrate a segment that returns the 5 bestsellers of a product collection.

Before

class Forest::Product
  include ForestLiana::Collection

  collection :Product

    segment 'Bestsellers' do
      query = <<~SQL
        SELECT products.id, COUNT(orders.*)
        FROM products
        JOIN orders ON orders.product_id = products.id
        GROUP BY products.id
        ORDER BY count DESC
        LIMIT 5;
      SQL

      products = ActiveRecord::Base.connection.execute(query)
      { id: products.map { |product| product['id'] } }
    end
end

After

module ForestAdminRails
  class CreateAgent
    def self.setup!
      @create_agent.customize_collection('product') do |collection|
        collection.add_segment('best_sellers') do |context|
          rows = ActiveRecord::Base.connection.execute(
            'SELECT products.id as product_id, COUNT(orders.id) as nb
             FROM products
             INNER JOIN orders ON orders.product_id = products.id
             GROUP BY products.id
             ORDER BY nb DESC
             LIMIT 5;'
          )

          {
            field: 'id',
            operator: 'In',
            value: rows.map { |r| r['product_id'] }
          }
        end
      end
    end
  end
end