How can I format the value shown in a Rails edit field?

Question

I would like to make editing form fields as user-friendly as possible. For example, for numeric values, I would like the field to be displayed with commas (like number

Answer 1

This is an old question, but in case anyone comes across this you could use the number_to_X helpers. They have all of the attributes you could ever want for displaying your edit value:

<%= f.text_field :my_number, :value => number_to_human(f.object.my_number, :separator => '', :unit => '', :delimiter => '', :precision => 0) %>

There are more attributes available too: http://api.rubyonrails.org/classes/ActionView/Helpers/NumberHelper.html