Datamapper DataMapper

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  kgiszczak June 3rd, 2010 @ 08:39 AM

  • Assigned user set to “Piotr Solnica (solnic)”

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  Todd Richmond November 1st, 2013 @ 02:09 PM

  This makes single flag checks impossible and is still occurring in the most recent DataMapper Release. The workaround from a few different web posts is to use

  :conditions => ['flags & 1 != 0'], but that requires converting Flag symbols to integers manually

  Test.first :flags -> [:one] must create this SQL to return any item with that bit set in the bitmask

  SELECT "id", "flags" FROM "tests" WHERE "flags" & 1 != 0 ORDER BY "id" LIMIT 1

  Multiple flags would create an AND set of bit checks

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  Todd Richmond November 7th, 2013 @ 01:03 PM

  Here is a very ugly monkey patch because the comparison logic is in dm-core, but the new Flag type is in dm-types. However, it gives a clear example of the logic I implemented to match all operators

  module DataMapper
  module Adapters class DataObjectsAdapter < AbstractAdapter alias_method :override_comparison_statement, :comparison_statement

    def comparison_statement(comparison, qualify)
      subject = comparison.subject
      value = comparison.value
  
      if subject.respond_to?(:model) && subject.model.properties[subject.name].options[:flags] &&
        value.is_a?(Array) ? value.first.is_a?(Fixnum) : value.is_a?(Fixnum)
        column_name = property_to_column_name(subject, qualify)
        value = value.inject(0, :+) if value.is_a?(Array)
        case comparison.slug
        when :eql then "#{column_name} = #{value}"
        when :gt then "#{column_name} & #{value} = #{value} AND #{column_name} != #{value}"
        when :gte then "#{column_name} & #{value} = #{value}"
        when :in, :like then value == 0 ? 'TRUE' : "#{column_name} & #{value} != 0"
        when :lt then "#{column_name} & #{value} != #{value}"
        when :lte then "#{column_name} & #{value} <= #{value}"
        else 'FALSE'
        end
      else
        override_comparison_statement(comparison, qualify)
      end
    end
  end
  

  end end