Merb devel - Dec 2007 - Loading config YAML into merb process for the life of the process

Hey Chaps,

Forgive me for not fully understanding the inner workings of merb, but  
I would like to read in a YAML configuration file once when the  
application is booted rather than reading it every time it is used (as  
presumably the overhead in doing that is significant?) - I had  
presumed this is how both Merb and rails do it for there database.yml  
config files (hence its a requirement to restart the process if you  
change the DB config) but after looking at the rails trunk there seems  
to be nothing obvious going on that would cache the returned  
configuration.

Are there hooks available so that gem plugins for merb can run code  
when the application is at different parts of booting? If so, how on  
earth would I then store said configuration?

Many thanks for any pointers

Tim

On Dec 30, 2007, at 3:34 PM, Tim Perrett wrote:
> Hey Chaps,
>
> Forgive me for not fully understanding the inner workings of merb, but
> I would like to read in a YAML configuration file once when the
> application is booted rather than reading it every time it is used (as
> presumably the overhead in doing that is significant?) - I had
> presumed this is how both Merb and rails do it for there database.yml
> config files (hence its a requirement to restart the process if you
> change the DB config) but after looking at the rails trunk there seems
> to be nothing obvious going on that would cache the returned
> configuration.
>
> Are there hooks available so that gem plugins for merb can run code
> when the application is at different parts of booting? If so, how on
> earth would I then store said configuration?
>
> Many thanks for any pointers
>
> Tim

Hey Tim-

	There are a few ways of doing this. The best way it to use the  
Merb::Plugins.config hash. If you generate a fresh plugin:

merb -P foobar

	Then look in the plugin at the lib/foobar.rb file you will see this:

# make sure we''re running inside Merb
if defined?(Merb::Plugins)

   # Merb gives you a Merb::Plugins.config hash...feel free to put  
your stuff in your piece of it
   Merb::Plugins.config[:foobar] = {
     :chickens => false
   }

   Merb::Plugins.add_rakefiles "foobar/merbtasks"
end


So your best bet is to load the yaml file here and store it away in  
the Merb::Plugins.config hash.. Something like this:


   # Merb gives you a Merb::Plugins.config hash...feel free to put  
your stuff in your piece of it
   Merb::Plugins.config[:foobar] = Erubis.load_yaml_file(MERB_ROOT /  
''config'' / ''foobar.yml'' )


Then you can put your foobar.yml  file inside of MERB_ROOT/config/   
And now in your app when you want to refer to the hash of stuff loaded  
from the yaml file you woudl access it like this:

  Merb::Plugins.config[:foobar][:somekey]


Doing it will Erubis.load_yaml_file  will load the yaml file and  
interpolate any erb tags inside of it before yaml loading it.

Make sense?

Cheers-

- Ezra Zygmuntowicz
-- Founder & Software Architect
-- ezra at engineyard.com
-- EngineYard.com

Hey Ezra,

Thanks, thats brilliant :)

Cheers

Tim

On 31 Dec 2007, at 00:12, Ezra Zygmuntowicz wrote:
> Hey Tim-
>
> 	There are a few ways of doing this. The best way it to use the  
> Merb::Plugins.config hash. If you generate a fresh plugin:
>
> merb -P foobar
>
> 	Then look in the plugin at the lib/foobar.rb file you will see this:
>
> # make sure we''re running inside Merb
> if defined?(Merb::Plugins)
>
>  # Merb gives you a Merb::Plugins.config hash...feel free to put  
> your stuff in your piece of it
>  Merb::Plugins.config[:foobar] = {
>    :chickens => false
>  }
>
>  Merb::Plugins.add_rakefiles "foobar/merbtasks"
> end
>
>
> So your best bet is to load the yaml file here and store it away in  
> the Merb::Plugins.config hash.. Something like this:
>
>
>  # Merb gives you a Merb::Plugins.config hash...feel free to put  
> your stuff in your piece of it
>  Merb::Plugins.config[:foobar] = Erubis.load_yaml_file(MERB_ROOT /  
> ''config'' / ''foobar.yml'' )
>
>
> Then you can put your foobar.yml  file inside of MERB_ROOT/config/   
> And now in your app when you want to refer to the hash of stuff  
> loaded from the yaml file you woudl access it like this:
>
> Merb::Plugins.config[:foobar][:somekey]
>
>
> Doing it will Erubis.load_yaml_file  will load the yaml file and  
> interpolate any erb tags inside of it before yaml loading it.
>
> Make sense?
>
> Cheers-
>
> - Ezra Zygmuntowicz