README.md
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# 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`:
```ruby
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:
```ruby
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`:
```ruby
# 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:
```ruby
class Post < ActiveRecord::Base
include SafeFinder
safe_attribute :title, "Null"
safe_method :some_method do
"Do Something"
end
end
```
```ruby
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:
```ruby
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`
```ruby
module SafeFinder
class NullObject
def hello
"Hello"
end
end
end
```
```ruby
null_object = Post.null_object
null_object.hello # "Hello"
```
## TODOs
- Add association support, like `user.post` should also returns `Null 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](https://rubygems.org).
## Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/st0012/SafeFinder.