Rails - Nov 2005 - How to find out which actions are available on a controller?

Hi!

How can I find out which actions a controller supports? I want something
like

  is_available( :controller => ''foo'', :action =>
''bar'' )

which tells me whether a link to

  url_for( :controller => ''foo'', :action =>
''bar'' )

will succeed.

I want to dynamically place links on a page to actions on some specific
controller, but only when this action is actually supported.

Jochen
-- 
Jochen Topf  jochen-VkTBmBTYYDUdnm+yROfE0A@public.gmane.org 
http://www.remote.org/jochen/  +49-721-388298

Jochen Topf wrote:
> Hi!
> 
> How can I find out which actions a controller supports? I want something
> like
> 
>   is_available( :controller => ''foo'', :action =>
''bar'' )
> 
> which tells me whether a link to
> 
>   url_for( :controller => ''foo'', :action =>
''bar'' )
> 
> will succeed.
> 
> I want to dynamically place links on a page to actions on some specific
> controller, but only when this action is actually supported.
Since actions are just methods you could use ruby reflection to get all 
methods of the controller:

#!/usr/bin/ruby

class Test
   def ciao
     print "ciao!\n"
   end
end

class Hello
   #all methods that the class supports:
   #print a.methods.sort.join("\n")

   #public instance methods:
   print Test.public_instance_methods(false)
   print "\n"

   #or use the respond_to? method to see if a known
   #method is supported
   #print a.respond_to?(:ciao)
end

Jochen Topf wrote:
>Hi!
>
>How can I find out which actions a controller supports? I want something
>like
>
>  is_available( :controller => ''foo'', :action =>
''bar'' )
>
>which tells me whether a link to
>
>  url_for( :controller => ''foo'', :action =>
''bar'' )
>
>will succeed.
>
>I want to dynamically place links on a page to actions on some specific
>controller, but only when this action is actually supported.
>
>Jochen
>  
>
If you''re inside the controller you can call 
action_methods.include?(''bar''). From the outside,
it''s
FooController.action_methods.include?(''bar'').

-- stefan

On Sat, Nov 19, 2005 at 04:27:39PM +0100, Stefan Kaes
wrote:
> Jochen Topf wrote:
> 
> >Hi!
> >
> >How can I find out which actions a controller supports? I want
something
> >like
> >
> > is_available( :controller => ''foo'', :action =>
''bar'' )
> >
> >which tells me whether a link to
> >
> > url_for( :controller => ''foo'', :action =>
''bar'' )
> >
> >will succeed.
> >
> >I want to dynamically place links on a page to actions on some specific
> >controller, but only when this action is actually supported.
> >
> >Jochen
> > 
> >
> If you''re inside the controller you can call 
> action_methods.include?(''bar''). From the outside,
it''s
> FooController.action_methods.include?(''bar'').
Thanks. That solves half of the problem. But is there also a way to get
from the string ''foo'' to the controller
''FooController''? This would make
things look a bit nicer and consistent with other functions. I am sure
there must be a function for this somewhere in Rails, because it has to
do it itself for each request, but I can''t find it.

Jochen
-- 
Jochen Topf  jochen-VkTBmBTYYDUdnm+yROfE0A@public.gmane.org 
http://www.remote.org/jochen/  +49-721-388298

On 19-nov-2005, at 19:14, Jochen Topf wrote:
> On Sat, Nov 19, 2005 at 04:27:39PM +0100, Stefan Kaes wrote:
>> Jochen Topf wrote:
>>
>>> Hi!
>>>
>>> How can I find out which actions a controller supports? I want  
>>> something
>>> like
>>>
>>> is_available( :controller => ''foo'', :action
=> ''bar'' )
>>>
>>> which tells me whether a link to
>>>
>>> url_for( :controller => ''foo'', :action =>
''bar'' )
>>>
>>> will succeed.
>>>
>>> I want to dynamically place links on a page to actions on some  
>>> specific
>>> controller, but only when this action is actually supported.
>>>
>>> Jochen
>>>
>>>
>> If you''re inside the controller you can call
>> action_methods.include?(''bar''). From the outside,
it''s
>> FooController.action_methods.include?(''bar'').
>
> Thanks. That solves half of the problem. But is there also a way to  
> get
> from the string ''foo'' to the controller
''FooController''? This would
> make
> things look a bit nicer and consistent with other functions. I am sure
> there must be a function for this somewhere in Rails, because it  
> has to
> do it itself for each request, but I can''t find it.
Jochen, you can take a look at the Inflector - methods as  
Inflector::modulize, symbolize, demodulize, constantize etc.
However, it "feels" to me that you are trying to do something which  
already IS in rails, you just not know how to get to it.

For instance, have you thought about asking Routes if your route is  
mappable and hiding the link if it''s not there? I think if you could  
do that
you would get away with much less code that what you are trying to do  
now.

On Sat, Nov 19, 2005 at 07:35:10PM +0100, Julian ''Julik''
Tarkhanov wrote:
> On 19-nov-2005, at 19:14, Jochen Topf wrote:
> 
> >On Sat, Nov 19, 2005 at 04:27:39PM +0100, Stefan Kaes wrote:
> >>Jochen Topf wrote:
> >>
> >>>Hi!
> >>>
> >>>How can I find out which actions a controller supports? I want
> >>>something
> >>>like
> >>>
> >>>is_available( :controller => ''foo'',
:action => ''bar'' )
> >>>
> >>>which tells me whether a link to
> >>>
> >>>url_for( :controller => ''foo'', :action
=> ''bar'' )
> >>>
> >>>will succeed.
> >>>
> >>>I want to dynamically place links on a page to actions on some
> >>>specific
> >>>controller, but only when this action is actually supported.
> >>>
> >>>Jochen
> >>>
> >>>
> >>If you''re inside the controller you can call
> >>action_methods.include?(''bar''). From the outside,
it''s
> >>FooController.action_methods.include?(''bar'').
> >
> >Thanks. That solves half of the problem. But is there also a way to  
> >get
> >from the string ''foo'' to the controller
''FooController''? This would
> >make
> >things look a bit nicer and consistent with other functions. I am sure
> >there must be a function for this somewhere in Rails, because it  
> >has to
> >do it itself for each request, but I can''t find it.
> 
> Jochen, you can take a look at the Inflector - methods as  
> Inflector::modulize, symbolize, demodulize, constantize etc.
> However, it "feels" to me that you are trying to do something
which
> already IS in rails, you just not know how to get to it.
> 
> For instance, have you thought about asking Routes if your route is  
> mappable and hiding the link if it''s not there? I think if you
could
> do that
> you would get away with much less code that what you are trying to do  
> now.
Well, how would I ask Routes if my route is mappable? I couldn''t find
any documentation about this.

Jochen
-- 
Jochen Topf  jochen-VkTBmBTYYDUdnm+yROfE0A@public.gmane.org 
http://www.remote.org/jochen/  +49-721-388298

Jochen Topf wrote:
>On Sat, Nov 19, 2005 at 04:27:39PM +0100, Stefan Kaes wrote:
>  
>
>>Jochen Topf wrote:
>>
>>    
>>
>>>Hi!
>>>
>>>How can I find out which actions a controller supports? I want
something
>>>like
>>>
>>>is_available( :controller => ''foo'', :action
=> ''bar'' )
>>>
>>>which tells me whether a link to
>>>
>>>url_for( :controller => ''foo'', :action =>
''bar'' )
>>>
>>>will succeed.
>>>
>>>I want to dynamically place links on a page to actions on some
specific
>>>controller, but only when this action is actually supported.
>>>
>>>Jochen
>>>
>>>
>>>      
>>>
>>If you''re inside the controller you can call 
>>action_methods.include?(''bar''). From the outside,
it''s
>>FooController.action_methods.include?(''bar'').
>>    
>>
>
>Thanks. That solves half of the problem. But is there also a way to get
>from the string ''foo'' to the controller
''FooController''? This would make
>things look a bit nicer and consistent with other functions. I am sure
>there must be a function for this somewhere in Rails, because it has to
>do it itself for each request, but I can''t find it.
>
>Jochen
>  
>
Fo top level controllers you can do

    Module.const_get(''foo''.camelize + "Controller")

If your controller lives inside a module, with a patch like
"admin/foo",
it''s probably

    Module.const_get("admin/foo".split("/").collect!{|m| 
m.camelize}.join("::") + "Controller")

But I''m not sure, as I haven''t used modules yet. Maybe
there''s a builtin
function for this.

-- stefan