Re: [Rails] How can I set up a proper getter/setter?

[Rob Biedenharn]

On 2016-Feb-8, at 19:19 , David McDonald <dave...@gmail.com> wrote:

I have a model named, Measurable, that stores many different types of of measurements for different things.  All the measurements can be represented as a decimal, so my value column is of datatype decimal.  My users though wish to view and input these value is either integers or mixed numbers (ex: 31 1/8) as well, depending on the measurable_type.  Right now I'm able to convert the mixed number to a decimal value and store it into my database as a proper decimal. But I'm trying to figure out how to convert it from a decimal value to the mixed number I'm wanting to show the user in my form, so they can make edits if necessary.  Below I have the setter method I made, but my attempts at creating a proper getter haven't work.  I'm not really sure how to go about it.

I think you want to at least consider using Ruby's Rational class to help. Here's a pure Ruby example:

class Measurable

  attr_accessor :id, :unit_id, :measurable_type_id, :reliability_id, :created_at, :updated_at

  attr_reader :value

  # belongs_to :measurable_type

  def initialize(input)

    self.value = input

  end

  def value=(input)

    case input

    when String

      # Has more than one value

      if (parts = input.split(" ")).size > 1

        result = parts.reduce(0) {|whole,part| whole + Rational(part) }

      else

        result = input.to_f

      end

    when Numeric

      result = input

    else

      result = input.to_f

    end

    @value = result

  end

  def to_s

    case self.value

    when Rational

      whole = self.value.floor

      "%d %s"%[whole, (self.value - whole).to_s]

    else

      self.value.to_s

    end

  end

end

irb2.2.4> puts Measurable.new("31 1/8")

31 1/8

#2.2.4 => nil

irb2.2.4> puts Measurable.new("31.125")

31.125

#2.2.4 => nil

irb2.2.4> puts Measurable.new(31.125)

31.125

#2.2.4 => nil

There's also a to_r method to convert types to a Rational if your "measurable_type" wanted to convert strictly to a Rational form.

-Rob