Class: Sequel::Dataset

Inherits:
Object show all
Defined in:
lib/clevic/ar_methods.rb

Instance Method Summary collapse

Instance Method Details

#translate(options) ⇒ Object

Basically, we’re translating from AR’s hash options to Sequel’s method algebra, and returning the resulting dataset.



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# File 'lib/clevic/ar_methods.rb', line 9

def translate( options )
  # recursively send key-value pairs to self
  # and return the result
  options.inject( self ) do |dataset, (key, value)|
    case key
      when :limit; dataset.limit( value, nil )
      when :offset
        # workaround for Sequel's refusal to do offset without limit
        # not sure we need :all for >= 3.13.0
        dataset.limit( options[:limit] || :all, value )

      when :order
        orders = value.split(/, */ ).map do |x|
          case x
          when /^(\w+) +(asc|desc)$/i
            $1.to_sym.send( $2 )

          when /^\w+$/i
            x.to_sym

          else
            x.lit

          end
        end
        dataset.order( *orders )

      when :conditions
        # this translation is not adequate for all use cases of the AR api
        # specifically where value contains a SQL expression
        unless value.nil?
          possible_literal =
          if value.is_a?( String )
            value.lit
          else
            value
          end

          dataset.filter( possible_literal ) 
        end

      when :include
        # this is the class to join
        joined_class = eval( model.reflections[value][:class_name] )
        dataset.join_table(
          :inner,
          joined_class,
          joined_class.primary_key => model.reflections[value][:key]
        ).select( model.table_name.* )

      else
        raise "#{key} not implemented"
    # make sure at least it's unchanged, in case options is empty
    end || dataset
  end

  rescue Exception => e
    raise RuntimeError, "#{self} #{options.inspect} #{e.message}", caller(0)
end