SafeFinder
SafeFinder lets you define a model's Null Object
through a simple DSL, and returns that when you don't find an instance of that model.
Installation
Add this line to your application's Gemfile
:
gem 'safe_finder'
And then execute:
$ bundle
Or install it yourself as:
$ gem install safe_finder
Usage
Basic
Let's say you have a Post
class, and it has title
and content
column.
First, you need to include SafeFinder
in your model:
class Post < ActiveRecord::Base
include SafeFinder
end
Now you can query like this, and if it doesn't find anything it returns a Null Object
:
# It returns a Null Object
null_object = Post.safely.find_by_title("Not Exists")
null_object.class # NullPost
null_object.title # nil
null_object.content # nil
Custom Attributes and Methods
And you can customize the Null Object's attributes or methods using a DSL:
class Post < ActiveRecord::Base
include SafeFinder
safe_attribute :title, "Null"
safe_method :some_method do
"Do Something"
end
end
null_object = Post.safely.find_by_title("Not Exists")
null_object.title # "Null"
null_object.some_method # "Do Something"
Get a Null Object directly
Just simply use:
Post.null_object # <NullPost:0x007fa8a4713be0>
Inheritance
All Null Object
s inherit SafeFinder::NullObject
, so you can add it in
app/models/safe_finder/null_object.rb
by generate it with
rails g safe_finder:model
and define general methods for every Null Object
module SafeFinder
class NullObject
def hello
"Hello"
end
end
end
null_object = Post.null_object
null_object.hello # "Hello"
TODOs
- Add association support, like
user.post
should also returnsNull Object
when it's nil - More use cases in readme
Development
After checking out the repo, run bin/setup
to install dependencies. Then, run rake spec
to run the tests. You can also run bin/console
for an interactive prompt that will allow you to experiment.
To install this gem onto your local machine, run bundle exec rake install
. To release a new version, update the version number in version.rb
, and then run bundle exec rake release
, which will create a git tag for the version, push git commits and tags, and push the .gem
file to rubygems.org.
Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/st0012/SafeFinder.