自动将字符串转换为模型中的整数时的前导零的Rails标识

Question

I have a model in Rails which accepts an integer value. Sometimes it's submitted as a string with leading zeroes and I'd the option to output it as a string later with the leading zeroes.

I could store as a string in the db instead but I was wondering if there was another way. Simplified code below.

s = Speed.create(value: "03", measurement: "KPH")
expect(s.value).to eq(3)
expect(s.to_s).to eq("03KPH") # FAILS, returns "3KPH"
expect(s.padding).to eq(1) # FAILS, returns 0

I have a padding field in the database in which to store the number of leading zeroes.

Answer 1

If you want to keep original information about the string, then store it as a string rather than an integer. You can then add a method to translate it to an integer if needed, or just call "to_i" on it when you use it and want to use it as a number.

You could change your test to

s = Speed.create(value: "03", measurement: "KPH")
expect(s.value.to_i).to eq(3)
expect(s.to_s).to eq("03KPH") 
expect(s.padding).to eq(1)

Answer 2

You can manually set/get your active record attributes by doing something like below,

class Speed < ActiveRecord::Base
  def value=(i)
    self.value = i 
  end 

  def value
    value.to_i
  end 
end