yaml -> template file

[Brian Donahue]

Folks,

I am trying to do something that's probably mind-numbingly easy, but I'm far too obtuse to figure it out.  I'm using Rake to build a .NET project (ACK!) and I want to set some local settings in a yaml file then read it and do search and replaces of tokens in a template.  Such as:

yaml:

connection_string: blah

Template:
<ConnectionString>%connection_string%</ConnectionString>

Where at the end of the day, I'd create a new file from my template with the %connection_string% token replaced with the yaml value.

Is there an easy way to do this, so that you end up with symbols or a class that I can use in a replace function?  (i.e. end up with :connection_string or config.connection_string after loading the yaml)?

Thanks for any tips!

Brian

[Randy Schmidt]

You could pass it through erb or liquid.

[Randy Schmidt]

Or MUSTACHE! http://github.com/defunkt/mustache/

[Brian Donahue]

Those would work for the templating part, right?  I'm still trying to figure out how to load yaml and have it be accessible via an object or symbol.  I'm having trouble finding similar examples on google, and I know I'm missing something obvious.  I have:

config = YAML::load_file "local.properties.yaml"

"puts config" just spits the yaml back out.  My ruby is too weak to figure out what kind of object/structure is loaded into config... is it just a string, or is there a way to access each value in the yaml file by name?

[Randy Schmidt]

You could use something like openstruct to create an arbitrary object
with methods from the hash.

<creepy>Go ahead, ride the mustache, you know you want to. </creepy>

[Steve Eichert]

YAML::load_file with the sample you provided will be a hash, so you can access the value by passing in the key that you're interested in.  So config[:connection_string] should provide you back your connection string.

[Angel Pizarro]

Brian, 

config = YAML.load_file( '/path/to/file' ) 

will set config to be a Hash object. from your example yaml file, you can access the connection_string variable via:

config["connection_sting"] # => gives the string "blah" 

See the Erubis project documentation (specifically rendering templates with a context) for more examples. 

--
Angel

[Colin A. Bartlett]

You have mustache, Randy? Ooooh, I can't wait to ride it.

</creepier>

[Brian Donahue]

Thanks, Angel!  That is what was eluding me.

Looking forward to your CouchDB talk on Wednesday!

[Jason Yates]

ActiveSupport, technically a part of Rails, adds a to_xml method into
the Hash class, so you may not need templates as long as the XML and
YAML are structured the same.

require 'active_support'

config = YAML.load_file('/path/to/file');
# assert config.class == "Hash"
puts config.to_xml

The documentation is here(just run a find on to_xml, the to_xml in
ActiveSupport not ActiveRecord).

http://api.rubyonrails.org/

--
Jason Yates
jay...@gmail.com

[Brian Donahue]

Thanks for this!  That looks useful though in this case it's a complex XML file with a lot of other info in it I can't lose, so I am doing token replacement.  Got it working using the YAML hash Angel showed.

Thanks everyone,

Brian