Rails: Is There a Rails Trick to Adding Commas to Large Numbers

Rails: Is there a rails trick to adding commas to large numbers?

You want the number_with_delimiter method. For example:

<%= number_with_delimiter(@number, :delimiter => ',') %>

Alternatively, you can use the number_with_precision method to ensure that the number is always displayed with two decimal places of precision:

<%= number_with_precision(@number, :precision => 2, :delimiter => ',') %>

inserting commas to separate large number?

Use number_with_delimiter.

From your helpers:

number_with_delimiter(12345678)       # => 12,345,678

UPDATE: The code for the method.

Rails strip all except numbers commas and decimal points

Try:

rate = rate.gsub(/[^0-9,\.]/, '')

Basically, you know the ^ means not when inside the character class brackets [] which you are using, and then you can just add the comma to the list. The decimal needs to be escaped with a backslash because in regular expressions they are a special character that means "match anything".

Also, be aware of whether you are using gsub or gsub!

gsub! has the bang, so it edits the instance of the string you're passing in, rather than returning another one.

So if using gsub! it would be:

rate.gsub!(/[^0-9,\.]/, '')

And rate would be altered.

If you do not want to alter the original variable, then you can use the version without the bang (and assign it to a different var):

cleaned_rate = rate.gsub!(/[^0-9,\.]/, '')

I'd just google for tutorials. I haven't used one. Regexes are a LOT of time and trial and error (and table-flipping).

This is a cool tool to use with a mini cheat-sheet on it for ruby that allows you to quickly edit and test your expression:

http://rubular.com/

Chaining statements together with commas

It's not actually chaining statements, it's parallel assignment. It means: assign the value of b to a, and assign the value of a%b to b, at the same time.

Because the values are interdependent, it can't simply be written as:

# WRONG
a = b
b = a%b

You'd need a temporary variable:

# Correct, but more verbose and less readable
old_b = b
b = a%b
a = old_b

The same syntax is also useful when destructuring arrays, for example:

my_array = [1,2,3]
a, b, c = my_array

How to format a number 1000 as 1 000

see: http://www.justskins.com/forums/format-number-with-comma-37369.html

there is no built in way to it ( unless you using Rails, ActiveSupport Does have methods to do this) but you can use a Regex like

formatted_n = n.to_s.reverse.gsub(/...(?=.)/,'\&,').reverse

Allowing commas in a numerical field

I actually figured this out just as I was reading over my question.

The key is to use a virtual attribute.

class Job < ActiveRecord::Base
  def flexible_quantity
    quantity
  end

  def flexible_quantity=(quantity)
    self.quantity = quantity.gsub(',', '') unless quantity.blank?
  end
 end

Then in the form, use the virtual attribute.

<%= f.text_field :flexible_quantity %>

Now validate the presence of the flexible_quantity value instead.

class Job < ActiveRecord::Base
  validates :flexible_quantity, presence: true

  # The cool this is that we can leave the numericality validation on the quantity field.
  validates :quantity, presence: true, numericality: { only_integer: true }
end

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