Module: Linkage::Utils

Defined in:
lib/linkage/utils.rb

Constant Summary collapse

TYPE_CONVERSION_TREE =

A “tree” used to find compatible types.

{
  TrueClass => [Integer],
  Integer => [Bignum, Float],
  Bignum => [BigDecimal],
  Float => [BigDecimal],
  BigDecimal => [String],
  String => nil,
  DateTime => nil,
  Date => nil,
  Time => nil,
  File => nil
}

Instance Method Summary collapse

Instance Method Details

#merge_fields(field_1, field_2) ⇒ Array

Create field information for a field that can hold data from two other fields. If the fields have different types, the resulting type is determined via a type-conversion tree.

Parameters:

  • field_1 (Array) —

    Schema information for the first field

  • field_2 (Array) —

    Schema information for the second field

Returns:

  • (Array) —

    Schema information for the new field



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# File 'lib/linkage/utils.rb', line 24

def merge_fields(field_1, field_2)
  schema_1 = column_schema_to_ruby_type(field_1)
  schema_1.delete_if { |k, v| v.nil? }
  schema_2 = column_schema_to_ruby_type(field_2)
  schema_2.delete_if { |k, v| v.nil? }
  if schema_1 == schema_2
    result = schema_1
  else
    result = schema_1.dup

    # type
    if schema_1[:type] != schema_2[:type]
      result[:type] = first_common_type(schema_1[:type], schema_2[:type])
    end

    # text
    if schema_1[:text] != schema_2[:text]
      # This can only be of type String.
      result[:text] = true
      result.delete(:size)
    end

    # size
    if !result[:text] && schema_1[:size] != schema_2[:size]
      types = [schema_1[:type], schema_2[:type]].uniq
      if types.length == 1 && types[0] == BigDecimal
        # Two decimals
        if schema_1.has_key?(:size) && schema_2.has_key?(:size)
          s_1 = schema_1[:size]
          s_2 = schema_2[:size]
          result[:size] = [ s_1[0] > s_2[0] ? s_1[0] : s_2[0] ]

          if s_1[1] && s_2[1]
            result[:size][1] = s_1[1] > s_2[1] ? s_1[1] : s_2[1]
          else
            result[:size][1] = s_1[1] ? s_1[1] : s_2[1]
          end
        else
          result[:size] = schema_1.has_key?(:size) ? schema_1[:size] : schema_2[:size]
        end
      elsif types.include?(String) && types.include?(BigDecimal)
        # Add one to the precision of the BigDecimal (for the dot)
        if schema_1.has_key?(:size) && schema_2.has_key?(:size)
          s_1 = schema_1[:size].is_a?(Array) ? schema_1[:size][0] + 1 : schema_1[:size]
          s_2 = schema_2[:size].is_a?(Array) ? schema_2[:size][0] + 1 : schema_2[:size]
          result[:size] = s_1 > s_2 ? s_1 : s_2
        elsif schema_1.has_key?(:size)
          result[:size] = schema_1[:size].is_a?(Array) ? schema_1[:size][0] + 1 : schema_1[:size]
        elsif schema_2.has_key?(:size)
          result[:size] = schema_2[:size].is_a?(Array) ? schema_2[:size][0] + 1 : schema_2[:size]
        end
      else
        # Treat as two strings
        if schema_1.has_key?(:size) && schema_2.has_key?(:size)
          result[:size] = schema_1[:size] > schema_2[:size] ? schema_1[:size] : schema_2[:size]
        elsif schema_1.has_key?(:size)
          result[:size] = schema_1[:size]
        else
          result[:size] = schema_2[:size]
        end
      end
    end

    # fixed
    if schema_1[:fixed] != schema_2[:fixed]
      # This can only be of type String.
      result[:fixed] = true
    end
  end

  {:type => result.delete(:type), :opts => result}
end