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Tim Ferrell

2007-Jun-06 14:29 UTC

questions about inheritance in Rails

I am in the process of subclassing some things in a current Rails
project and would like some feedback on how I''m approaching it... what
I
have works but I''m not sure if there is a better way to approach this.
:-)

I am currently subclassing controllers like so:

class LookupsController < ApplicationController
  # GET /lookups
  def index
  end

  #-----------------------------------------------------------------
  # the rest of these methods are called from subclassed controllers
  #-----------------------------------------------------------------

  # GET /{controller_name}
  # GET /{controller_name}.xml
  def index_list
    render ''lookups/index'' and return if controller_name ==
''lookups''
    eval(''@'' + controller_name + '' = '' +
model_name + ''.find(:all)'')
    respond_to do |format|
      format.html { render ''lookups/list'' }
      format.xml  { render :xml => eval(''@'' +
controller_name +
''.to_xml'') }
    end
  end

  # ... and so on ...
end

class StatesController < LookupsController
  def index
    index_list
  end
end

and the shared view template looks like this;


<h1><%= pretty_controller_name %></h1>
<table>
  <thead>
  <tr>
    <td id="col_actions">Actions</td>
    <td id="col_name">Name</td>
  </tr>
  </thead>
  <tbody>
  <% for item in eval(''@'' + controller_name) %>
    <tr class="<%= cycle("even","odd")
%>">
      <td>
  <span class="itemActions">
  &nbsp;
      <%= link_to(image_tag(''item_delete.gif''),
             eval(model_name + ''_path(:id => item)''),
                    :confirm => ''Are you sure?'',
                    :method => :delete,
                    :class => ''image_link'') %>
      <%= link_to(image_tag(''item_edit.gif''),
                    eval(''edit_'' + model_name +
''_path(:id => item)''),
                    :class => ''image_link'') %>
  </span>
      </td>
      <td class="itemName">
  <%= item.name %> <span
class="itemCount">(<%pluralize(item.jobs.count, "job")
%>)</span>
      </td>
    </tr>
  <% end %>
  </tbody>
</table>
<br />
<%= submit_tag "Add a " + pretty_model_name, {:type =>
''button'',
:onClick=>"parent.location=''" +
eval(''new_'' + model_name + ''_path'') +
"''" } %>

and a helper like so:

module LookupsHelper
  def controller_name
    controller.controller_name
  end
  def model_name
    controller.controller_name.singularize
  end
  def pretty_model_name
    model_name.gsub(''_'', '' '').capitalize_all
  end
  def pretty_controller_name
    controller_name.gsub(''_'', ''
'').capitalize_all
  end
end

My main question revolves around the liberal use of eval() ... is there
a better way? Am I making this harder than it should be?

Thanks for any feedback...

Cheers,
Tim

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dblack-TKXtfPMJ4Ozk1uMJSBkQmQ@public.gmane.org

2007-Jun-06 14:39 UTC

head link

Re: questions about inheritance in Rails

Hi --

On Wed, 6 Jun 2007, Tim Ferrell wrote:
>
>
> I am in the process of subclassing some things in a current Rails
> project and would like some feedback on how I''m approaching it...
what I
> have works but I''m not sure if there is a better way to approach
this.
> :-)
>
> I am currently subclassing controllers like so:
>
> class LookupsController < ApplicationController
>  # GET /lookups
>  def index
>  end
>
>  #-----------------------------------------------------------------
>  # the rest of these methods are called from subclassed controllers
>  #-----------------------------------------------------------------
>
>  # GET /{controller_name}
>  # GET /{controller_name}.xml
>  def index_list
>    render ''lookups/index'' and return if controller_name
== ''lookups''
>    eval(''@'' + controller_name + '' = '' +
model_name + ''.find(:all)'')
>    respond_to do |format|
>      format.html { render ''lookups/list'' }
>      format.xml  { render :xml => eval(''@'' +
controller_name +
> ''.to_xml'') }
>    end
>  end
This is all sort of at first glance, so I could well be overlooking
some pitfalls, but why don''t you just say @items or something instead
of all the eval''ing?  Also, instead of model_name, you could have your
helper method return a model class.  That way, you could do:

   @items = model.find(:all)
>  # ... and so on ...
> end
>
> class StatesController < LookupsController
>  def index
>    index_list
>  end
> end
>
> and the shared view template looks like this;
>
>
> <h1><%= pretty_controller_name %></h1>
> <table>
>  <thead>
>  <tr>
>    <td id="col_actions">Actions</td>
>    <td id="col_name">Name</td>
>  </tr>
>  </thead>
>  <tbody>
>  <% for item in eval(''@'' + controller_name) %>
>    <tr class="<%= cycle("even","odd")
%>">
>      <td>
>  <span class="itemActions">
>  &nbsp;
>      <%= link_to(image_tag(''item_delete.gif''),
>             eval(model_name + ''_path(:id => item)''),
At the very least I would use send there:

   send("#{model_name}_path", :id => item)

But it''s nicer if you can encapsulated that kind of calculation in the
controller or a helper method.

I''ll leave it at that, pending feedback on what I''ve missed
:-)


David

-- 
Q. What is THE Ruby book for Rails developers?
A. RUBY FOR RAILS by David A. Black (http://www.manning.com/black)
    (See what readers are saying!  http://www.rubypal.com/r4rrevs.pdf)
Q. Where can I get Ruby/Rails on-site training, consulting, coaching?
A. Ruby Power and Light, LLC (http://www.rubypal.com)

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Tim Ferrell

2007-Jun-06 14:54 UTC

head link

Re: questions about inheritance in Rails

David wrote:>
> This is all sort of at first glance, so I could well be overlooking
> some pitfalls, but why don''t you just say @items or something
instead
> of all the eval''ing?  Also, instead of model_name, you could have
your
> helper method return a model class.  That way, you could do:
> 
>    @items = model.find(:all)
> 
Thanks... good point. :-) I was so focused on translating the existing 
code that I missed that.
> 
> At the very least I would use send there:
> 
>    send("#{model_name}_path", :id => item)
> 
> But it''s nicer if you can encapsulated that kind of calculation in
the
> controller or a helper method.
> 
In other words, wrap the route method invocation with a helper method to 
simplify the view code?

One other question comes to mind... in the view I am creating a 
button...

<%= submit_tag "Add a " + pretty_model_name, {:type =>
''button'',
:onClick=>"parent.location=''" +
eval(''new_'' + model_name + ''_path'') +
"''" } %>

Is there a cleaner way to do this besides building the onClick 
javascript?
> I''ll leave it at that, pending feedback on what I''ve
missed :-)
Thanks much for the feedback!

Cheers,
Tim

-- 
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dblack-TKXtfPMJ4Ozk1uMJSBkQmQ@public.gmane.org

2007-Jun-06 14:58 UTC

head link

Re: questions about inheritance in Rails

Hi --

On Wed, 6 Jun 2007, Tim Ferrell wrote:
>
> David wrote:
>>
>> This is all sort of at first glance, so I could well be overlooking
>> some pitfalls, but why don''t you just say @items or something
instead
>> of all the eval''ing?  Also, instead of model_name, you could
have your
>> helper method return a model class.  That way, you could do:
>>
>>    @items = model.find(:all)
>>
>
> Thanks... good point. :-) I was so focused on translating the existing
> code that I missed that.
>
>>
>> At the very least I would use send there:
>>
>>    send("#{model_name}_path", :id => item)
>>
>> But it''s nicer if you can encapsulated that kind of
calculation in the
>> controller or a helper method.
>>
>
> In other words, wrap the route method invocation with a helper method to
> simplify the view code?
Yes -- something like:

   def model_path(*args)
     send("#{model_name}_path", *args)
   end

at which point you could do:

   <%= link to "Click here", model_path :id => item %>

There may be yet further ways to simplify it all but initially at
least I''d go for pushing all the low-level-ish stuff out of the views
and see what happens.

(Punting on the JS question... :-)


David

-- 
Q. What is THE Ruby book for Rails developers?
A. RUBY FOR RAILS by David A. Black (http://www.manning.com/black)
    (See what readers are saying!  http://www.rubypal.com/r4rrevs.pdf)
Q. Where can I get Ruby/Rails on-site training, consulting, coaching?
A. Ruby Power and Light, LLC (http://www.rubypal.com)

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Rails - Jun 2007 - questions about inheritance in Rails

questions about inheritance in Rails

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