I am using a form select in ruby on rails. How do I get the blank default to show prompt message?

Question

= f.select:from_id, decorated_froms.map { |from| [from.name, from.id] }, include_blank: "Please select a role to send a message."

Answer 1

include_blank

<%= f.select :from_id, decorated_froms.map { |from| [from.name, from.id] }, include_blank: 'Please select a role to send a message.') %>

This will always include a blank option in the select, which will allow people to set the value back to the blank value if they're seeing this on an edit form.

prompt which is the better option

<%= f.select :from_id, decorated_froms.map { |from| [from.name, from.id] }, prompt: 'Please select a role to send a message.') %>

This will include the specified prompt value, so long as the field hasn't already been set. If it has (on an edit form for example), there's no need to remind the user that they need to select a value so the prompt doesn't appear.

More on #select https://apidock.com/rails/ActionView/Helpers/FormOptionsHelper/select