Continuing with my series on the Nifty Generators gem by Ryan Bates (see part 1 on nifty_layout), in this post I want to talk about a second feature this gem provides, called
nifty_config, you can quickly create a set of global variables for your application, dependent on the environment in which your Rails application is currently running.
To get started, generate a config file:
This adds two files to your app: A configuration file called
app_config.yml located inside
config, and an initializer (to load the config file when your Rails app starts) in
From there you can customize the default values created by the generator. For example, I use the Passenger preference pane for Mac OS X to manage multiple local development environments, instead of running
script/server within my apps. The preference pane defaults to
appname.local as its convention, so I use that as my local domain.
You can also add your own values to the YAML file. For me, the most useful addition is an e-mail address for mailers to use when sending e-mail. I might use a personal account during development, but a more official contact address once the app is in production. I sometimes also include a
name value for each environment, mainly because there are times I’ll start on application development before I know what it’s going to be called–so I use some sort of code name during development, and want to have placeholders for the final name. This isn’t always a good practice, but it generally works for me. It’s no substitute for error-checking your views and your copy before deployment, though.
Here’s what a completed
config.yml file might look like for me:
Don’t forget: The values in your
app_config.yml file are loaded when your application starts, so you’ll need to restart your application after you first create the file or whenever you make changes to its values.
From there, it’s just a matter of calling up your values wherever they’re needed. All you need to do is refer to
APP_CONFIG[:value] within your application’s code to use whatever you assigned to
value in your
config.yml file, for the environment in which your app is currently running. For example, given the above configuration file,
APP_CONFIG[:email] would return
firstname.lastname@example.org if I were running the code in development mode; it would return
email@example.com if I were in production.
So in a standard Rails view file, you might include your application’s name like
Using Haml, I’d write the above like
Or in a mailer model like
Here’s a simple example of using APP_CONFIG values outside of view-type files. In this case, I wanted to limit the number of people who could create accounts while I was scaling up. I created a
max_users value in my
app_config.yml file, then called the below method with a
before_filter call in the controller that created new user accounts.
That’s all for Nifty Generators’ nifty_config feature. These are my uses for it, but I recommend experimenting with it in your own apps. Next time I’ll close out my series on Nifty Generators with
nifty_scaffold, the real meat of this very useful gem.
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