Add this line to your application's Gemfile:
gem 'decent_exposure', '~> 3.0'
And then execute:
$ bundle
Or install it yourself as:
$ gem install decent_exposure
The whole API consists of three methods so far: expose
, expose!
, and
exposure_config
.
In the simplest scenario you'll just use it to expose a model in the controller:
class ThingsController < ApplicationController
expose :thing
end
Now every time you call thing
in your controller or view, it will look for an
ID and try to perform Thing.find(id)
. If the ID isn't found, it will call
Thing.new(thing_params)
. The result will be memoized in an @exposed_thing
instance variable.
Here's what a standard Rails 5 CRUD controller using Decent Exposure might look like:
class ThingsController < ApplicationController
expose :things, ->{ Thing.all }
expose :thing
def create
if thing.save
redirect_to thing_path(thing)
else
render :new
end
end
def update
if thing.update(thing_params)
redirect_to thing_path(thing)
else
render :edit
end
end
def destroy
thing.destroy
redirect_to things_path
end
private
def thing_params
params.require(:thing).permit(:foo, :bar)
end
end
The default resolving workflow is pretty powerful and customizable. It could be expressed with the following pseudocode:
def fetch(scope, id)
instance = id ? find(id, scope) : build(build_params, scope)
decorate(instance)
end
def id
params[:thing_id] || params[:id]
end
def find(id, scope)
scope.find(id)
end
def build(params, scope)
scope.new(params) # Thing.new(params)
end
def scope
model # Thing
end
def model
exposure_name.classify.constantize # :thing -> Thing
end
def build_params
if respond_to?(:thing_params, true) && !request.get?
thing_params
else
{}
end
end
def decorate(thing)
thing
end
The exposure is also lazy, which means that it won't do anything until you call
the method. To eliminate this laziness you can use the expose!
macro instead,
which will try to resolve the exposure in a before filter.
It is possible to override each step with options. The acceptable options to the
expose
macro are:
This is the entry point. The fetch
proc defines how to resolve your exposure
in the first place.
expose :thing, fetch: ->{ get_thing_some_way_or_another }
Because the above behavior overrides the normal workflow, all other options would be ignored. However, Decent Exposure is decent enough to actually blow up with an error so you don't accidentally do this.
There are other less verbose ways to pass the fetch
block, since you'll
probably be using it often:
expose(:thing){ get_thing_some_way_or_another }
Or
expose :thing, ->{ get_thing_some_way_or_another }
Or even shorter
expose :thing, :get_thing_some_way_or_another
There is another shortcut that allows you to redefine the entire fetch block with less code:
expose :comments, from: :post
# equivalent to
expose :comments, ->{ post.comments }
The default fetch logic relies on the presence of an ID. And of course Decent Exposure allows you to specify how exactly you want the ID to be extracted.
Default behavior could be expressed using following code:
expose :thing, id: ->{ params[:thing_id] || params[:id] }
But nothing is stopping you from throwing in any arbitrary code:
expose :thing, id: ->{ 42 }
Passing lambdas might not always be fun, so here are a couple of shortcuts that could help make life easier.
expose :thing, id: :custom_thing_id
# equivalent to
expose :thing, id: ->{ params[:custom_thing_id] }
expose :thing, id: [:try_this_id, :or_maybe_that_id]
# equivalent to
expose :thing, id: ->{ params[:try_this_id] || params[:or_maybe_that_id] }
If an ID was provided, Decent Exposure will try to find the model using it. Default behavior could be expressed with this configuration:
expose :thing, find: ->(id, scope){ scope.find(id) }
Where scope
is a model scope, like Thing
or User.active
or
Post.published
.
Now, if you're using FriendlyId or Stringex or something similar, you'd have to customize your finding logic. Your code might look somewhat like this:
expose :thing, find: ->(id, scope){ scope.find_by!(slug: id) }
Again, because this is likely to happen a lot, Decent Exposure gives you a decent shortcut so you can get more done by typing less.
expose :thing, find_by: :slug
When an ID is not present, Decent Exposure tries to build an object for you. By default, it behaves like this:
expose :thing, build: ->(thing_params, scope){ scope.new(thing_params) }
These options are responsible for calulating params before passing them to the
build step. The default behavior was modeled with Strong Parameters in mind and
is somewhat smart: it calls the thing_params
controller method if it's
available and the request method is not GET
. In all other cases it produces
an empty hash.
You can easily specify which controller method you want it to call instead of
thing_params
, or just provide your own logic:
expose :thing, build_params: :custom_thing_params
expose :other_thing, build_params: ->{ { foo: "bar" } }
private
def custom_thing_params
# strong parameters stuff goes here
end
Defines the scope that's used in find
and build
steps.
expose :thing, scope: ->{ current_user.things }
expose :user, scope: ->{ User.active }
expose :post, scope: ->{ Post.published }
Like before, shortcuts are there to make you happier:
expose :post, scope: :published
# equivalent to
expose :post, scope: ->{ Post.published }
and
expose :thing, parent: :current_user
# equivalent to:
expose :thing, scope: ->{ current_user.things }
Allows you to specify the model class to use. Pretty straightforward.
expose :thing, model: ->{ AnotherThing }
expose :thing, model: AnotherThing
expose :thing, model: "AnotherThing"
expose :thing, model: :another_thing
Before returning the thing, Decent Exposure will run it through the decoration process. Initially, this does nothing, but you can obviously change that:
expose :things, ->{ Thing.all.map{ |thing| ThingDecorator.new(thing) } }
expose :thing, decorate: ->(thing){ ThingDecorator.new(thing) }
You can pre-save some configuration with exposure_config
method to reuse it
later.
exposure_config :cool_find, find: ->{ very_cool_find_code }
exposure_config :cool_build, build: ->{ very_cool_build_code }
expose :thing, with: [:cool_find, :cool_build]
expose :another_thing, with: :cool_build
Mailers and Controllers use the same decent_exposure dsl.
class PostMailer < ApplicationMailer
expose(:posts, -> { Post.last(10) })
expose(:post)
def top_posts
@greeting = "Top Posts"
mail to: "to@example.org"
end
def featured_post(id:)
@greeting = "Featured Post"
mail to: "to@example.org"
end
end
If you want to generate rails scaffold templates prepared for decent_exposure
run:
rails generate decent_exposure:scaffold_templates [--template_engine erb|haml]
This will create the templates in your lib/templates
folder.
Make sure you have configured your templates engine for generators in config/application.rb
:
# config/application.rb
config.generators do |g|
g.template_engine :erb
end
Now you can run scaffold like:
rails generate scaffold post title description:text
- Fork it (https://github.com/hashrocket/decent_exposure/fork)
- Create your feature branch (
git checkout -b my-new-feature
) - Commit your changes (
git commit -am 'Add some feature'
) - Push to the branch (
git push origin my-new-feature
) - Create a new Pull Request
Decent Exposure is supported by the team at Hashrocket, a multidisciplinary design & development consultancy. If you'd like to work with us or join our team, don't hesitate to get in touch.