leading zeros in rails

I have fields hr and min, both integers in my application. For hr field, if the user enters "1" I would like Rails to automatically pad it to "01" before saving it to the database. Also for the min field if the user enter "0" it should put in as "00".

How can I do this?

It'd be better to store it as an integer and just display it as you described on runtime. Every language has its own way to pad zeros - for Ruby you can use String#rjust. This method pads a string (right-justified) so that it becomes a given length, using a given padding character.

> str.rjust(integer, padstr=' ') → new_str > > If integer is greater than the length of str, returns a new String of length integer with str right justified and padded with padstr; otherwise, returns str.

some_int = 5
some_int.to_s.rjust(2, '0')  # => '05'
some_int.to_s.rjust(5, '0')  # => '00005'

another_int = 150
another_int.to_s.rjust(2, '0') # => '150'
another_int.to_s.rjust(3, '0') # => '150'
another_int.to_s.rjust(5, '0') # => '00150'

You can transform the integer into a string of that kind with:

result_string = '%02i' % your_integer

This is independent from how it gets saved in the db.

• RDoc Documentation

• Explanation & Examples

This is also quite handy:

"%.2d" % integer

The resultant string will be of 2 characters and if the number is of less than 2 characters, then 0s will be present in the string

You can't store 01 as integer. It will be converted to 1

You can store it as a string, or you can show it as a string "01"

I like the % operator, even though it seems to have gone out of favor...

2.0.0-p247 :001 > '%02i' % 1
 => "01"
2.0.0-p247 :002 > '%2i' % 1
 => " 1"
2.0.0-p247 :003 > '%-2i' % 1
 => "1 "

Another way to achieve this is to pad your integer at display time, using sprintf:

f = sprintf '%04d', 49
# f = "0049"

Try this and you can change them to match

def numeric92(num)
  if num.present?
    if num < 0 && num > -1
      ('-%05d' % num) + '.' + ('%.2f' % num).split('.').last
    else
      ('%06d' % num) + '.' + ('%.2f' % num).split('.').last
    end
  else
    '000000.00'
  end
end