Rails - Sep 2007 - How can I create array of strings or a hash from ActiveRecord result set?

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-/E1597aS9LQAvxtiuMwx3w@public.gmane.org'',
''Email Everybody 1'', :subject =>
''Subject'', :bcc => @emails1.join('','')
%>
<%= mail_to ''me-/E1597aS9LQAvxtiuMwx3w@public.gmane.org'',
''Email Everybody 2'', :subject =>
''Subject'', :bcc => @emails2 %>
<%= mail_to ''me-/E1597aS9LQAvxtiuMwx3w@public.gmane.org'',
''Email Group '' + @group_id, :subject =>
''Subject'', :bcc =>
@emails[@group_id].join('','') %>
etc


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@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:
> 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-/E1597aS9LQAvxtiuMwx3w@public.gmane.org'', ''Email
Everybody 1'', :subject =>
> ''Subject'', :bcc =>
@emails1.join('','') %>
> <%= mail_to
''me-/E1597aS9LQAvxtiuMwx3w@public.gmane.org'', ''Email
Everybody 2'', :subject =>
> ''Subject'', :bcc => @emails2 %>
> <%= mail_to
''me-/E1597aS9LQAvxtiuMwx3w@public.gmane.org'', ''Email
Group '' + @group_id, :subject =>
> ''Subject'', :bcc =>
@emails[@group_id].join('','') %>
> etc
>
>
> >
>   
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This is amazing. Works perfect.
Thanks!!!


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On 9/26/07, eafonsof <eafonsof-/E1597aS9LQAvxtiuMwx3w@public.gmane.org>
wrote:
>
>
> This is amazing. Works perfect.
> Thanks!!!

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

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On Sep 26, 2007, at 12:49 AM, William Pratt wrote:
> eafonsof wrote:
>> 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-/E1597aS9LQAvxtiuMwx3w@public.gmane.org'', ''Email
Everybody 1'', :subject =>
>> ''Subject'', :bcc =>
@emails1.join('','') %>
>> <%= mail_to
''me-/E1597aS9LQAvxtiuMwx3w@public.gmane.org'', ''Email
Everybody 2'', :subject =>
>> ''Subject'', :bcc => @emails2 %>
>> <%= mail_to
''me-/E1597aS9LQAvxtiuMwx3w@public.gmane.org'', ''Email
Group '' + @group_id, :subject =>
>> ''Subject'', :bcc =>
@emails[@group_id].join('','') %>
>> etc
>
> @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.
@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 ;-)

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob-xa9cJyRlE0mWcWVYNo9pwxS2lgjeYSpx@public.gmane.org



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