How can I create array of strings or a hash from ActiveRecord result set?

rubyonrails-talk
1

Is there a way to do that in a single shot? Or what's the most efficient way of doing that? I've researched a lot but did not find out how to do it yet. Any help will be much appreciated.

Example (the syntax is not correct is some cases):

- Models:   User belongs_to :group   Group has_many :users

- Controller:   #User columns: id, email, group_id, etc.   @users = User.find(:all, :order => "group_id")

  #Things I wanted to have:   #@emails1 = array of all emails, i.e. [email_1,email_2, etc]   #@emails2 = string with all emails joined, i.e. "email_1,email_2,email_3,etc"   #@emails3 = hash/map with all emails grouped by group_id, i.e. [group_id_1 => [email_1,email_2], group_id_2 => [email_3,email_4,email_5],etc]

- View: <%= mail_to 'me@yahoo.com', 'Email Everybody 1', :subject => 'Subject', :bcc => @emails1.join(',') %> <%= mail_to 'me@yahoo.com', 'Email Everybody 2', :subject => 'Subject', :bcc => @emails2 %> <%= mail_to 'me@yahoo.com', 'Email Group ' + @group_id, :subject => 'Subject', :bcc => @emails[@group_id].join(',') %> etc

2

@users = User.find(:all, :order => "group_id") @emails1 = @users.collect{|u| u.email} @emails2 = @emails1.join ',' @emails3 = {} @users.each{|u| @emails3[u.group_id] ||= ; @emails3[u.group_id] << u.email}

There may be a more creative way to do the last one, but this should get you started.

eafonsof wrote:

3

This is amazing. Works perfect. Thanks!!!

4

The email array and string part are pretty much as William has shown. For the grouped email hash you can use the group_by method which is part of enumerable. It’s a bit slower than manually doing it. But depending on your tastes it might suit you better.

@emails3 = @users.group_by(&:group_id).each{ |email_array| email_array.map!(&:email) }

HTH Daniel

5

@users = User.find(:all, :order => "group_id") @emails1 = @users.map(&:email)

@emails2 = @emails1.join ','

@emails3 = @users.inject(Hash.new {|h,k| h[k] = }) {|h,u| h[u.group_id] << u.email; h}

Well, that last one might be a bit too creative for some :wink:

-Rob

Rob Biedenharn http://agileconsultingllc.com Rob@AgileConsultingLLC.com