Rails - Apr 2006 - Pagination with letter (A B C D ... Z)

Hi there,

Is there a neat and easy way to implement pagination with letters  
rather than numbers eg :

A B C D ... Z

Rob

Robert Zolkos wrote:
> Hi there,
>
> Is there a neat and easy way to implement pagination with letters  
> rather than numbers eg :
>
> A B C D ... Z
I''ve implemented somehting akin to this in my latest Rails app.  I have
a partial, called _filter.rhtml, that looks like this:

<div id="filterButtons">
<% LETTERS.each do |l| %>
 <%= if params[:filter] == l
      link_to(l, { :filter => l }, { :id =>
''selectedFilterButton'' })
     else
       link_to(l, :filter => l)
     end -%>
<% end %>
</div>

This creates links for all 26 letters across the top of my list page.

Then, in the controller, I use the :filter param value like so:

  def list
    params[:filter] = ''All'' unless params.has_key?(:filter)

    if params[:filter] == ''All''
      @server_pages, @servers = paginate(:servers, :per_page => 10,
       :order_by => ''name'')
    else
      @server_pages, @servers = paginate(:servers, :per_page => 10,
       :conditions => lambda { |r| r.name[0..0].upcase == params[:filter] },
       :order_by => ''name'')
    end
  end

So, if a user clicks on "B", it will show all servers whose name
begins
with B.  Note that in the :condtions hash value above, I am using a 
lambda.  This is because I am using Ackbar/KirbyBase as the dbms.  If 
you are using a regular dbms like MySQL, you would want to use a SQL 
statement as your :conditions value.

HTH,

Jamey

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I am a bit concerned that the direct use of the params hash in your  
conditions would leave you open to SQL injection attacks.  Since you are  
using a different database, it may be a non-issue, but in general it is  
dangerous to put stuff from your params hash directly into your find  
statements without some sort of sanitizing.
>
>  def list
>    params[:filter] = ''All'' unless
params.has_key?(:filter)
>
>    if params[:filter] == ''All''
>      @server_pages, @servers = paginate(:servers, :per_page => 10,
>       :order_by => ''name'')
>    else
>      @server_pages, @servers = paginate(:servers, :per_page => 10,
>       :conditions => lambda { |r| r.name[0..0].upcase
=>params[:filter] },
>       :order_by => ''name'')
>    end
>  end
>
_Kevin

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Well, this is an intranet app for my company, so I wasn''t too concerned
about injection attacks when I wrote it, but you do have a good point.

Also, since the lambda is actually a Ruby code block, it wouldn''t be a 
SQL injection attack that would have to be used, but, again, in general, 
your point is well taken.

Jamey

Kevin Olbrich wrote:
>I am a bit concerned that the direct use of the params hash in your  
>conditions would leave you open to SQL injection attacks.  Since you are  
>using a different database, it may be a non-issue, but in general it is  
>dangerous to put stuff from your params hash directly into your find  
>statements without some sort of sanitizing.
>
>  
>
>> def list
>>   params[:filter] = ''All'' unless
params.has_key?(:filter)
>>
>>   if params[:filter] == ''All''
>>     @server_pages, @servers = paginate(:servers, :per_page => 10,
>>      :order_by => ''name'')
>>   else
>>     @server_pages, @servers = paginate(:servers, :per_page => 10,
>>      :conditions => lambda { |r| r.name[0..0].upcase
=>>params[:filter] },
>>      :order_by => ''name'')
>>   end
>> end
>>
>>    
>>
>
>_Kevin
>
>  
>

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How about

# your table and field names will vary...
@alpha = find_by_sql(''select distinct substr(short_desc,1,1) from
listings
order by short_desc'')

the resultant AR recordset provides only the letters used (why use the whole
alphabet if only certain letters are used. Then, your pagination links look
like:

<!-- crude attempt at link generation :) -->
<% @alpha.each do |a| %>
  <%= link_to(a, :action => show_page, :start_with => a)
%>&nbsp;
<% end %>
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I''d just like to point out that

"A".upto("Z") do ...

is a lot better than

LETTERS = %w(A B C D ....
LETTERS.each do

--
Kyle Maxwell
Chief Technologist
E Factor Media // FN Interactive
kyle@efactormedia.com
1-866-263-3261

Kyle Maxwell wrote:
>I''d just like to point out that
>
>"A".upto("Z") do ...
>
>is a lot better than
>
>LETTERS = %w(A B C D ....
>LETTERS.each do
>  
>
Except for the fact that my LETTERS constant looks like this:

LETTERS = [''All'', ''0'',
''1'', ''2'', ... ''X'',
''Y'', ''Z'']

Because our server names can begin with a number and I also want to give 
the user the ability to select all servers.

So, I probably should have picked a different name for the constant, but 
I can''t just use #upto like you suggest.

Jamey

<...>
> Except for the fact that my LETTERS constant looks like this:
>
> LETTERS = [''All'', ''0'',
''1'', ''2'', ... ''X'',
''Y'', ''Z'']
> So, I probably should have picked a different name for the constant, but
> I can''t just use #upto like you suggest.
Some typing...

LETTERS =
[''All'',(0..1).to_a,(''A''..''Z'').to_a].flatten

Still not sure if this is most optimal way.


Regards,
Rimantas
--
http://rimantas.com/

On 11/04/2006, at 11:10 PM, Jamey Cribbs wrote:
>> I''d just like to point out that
>>
>> "A".upto("Z") do ...
>>
>> is a lot better than
>>
>> LETTERS = %w(A B C D ....
>> LETTERS.each do
>>
> Except for the fact that my LETTERS constant looks like this:
>
> LETTERS = [''All'', ''0'',
''1'', ''2'', ... ''X'',
''Y'', ''Z'']
>
> Because our server names can begin with a number and I also want to  
> give the user the ability to select all servers.
>
> So, I probably should have picked a different name for the  
> constant, but I can''t just use #upto like you suggest.
LETTERS =
[''All'']+("1".."9").to_a+("A".."Z").to_a

Avoids all that pesky typing ;)

--
Phillip Hutchings
phillip.hutchings@sitharus.com
http://www.sitharus.com/

> LETTERS =
[''All'',(0..1).to_a,(''A''..''Z'').to_a].flatten
oops, (0..9).to_a, of course


Regards,
Rimantas
--
http://rimantas.com/