HasScope
¶ ↑
Has scope allows you to map incoming controller parameters to named scopes in your resources. Imagine the following model called graduations:
class Graduation < ActiveRecord::Base scope :featured, -> { where(featured: true) } scope :by_degree, -> degree { where(degree: degree) } scope :by_period, -> started_at, ended_at { where("started_at = ? AND ended_at = ?", started_at, ended_at) } end
You can use those named scopes as filters by declaring them on your controller:
class GraduationsController < ApplicationController has_scope :featured, type: :boolean has_scope :by_degree end
Now, if you want to apply them to an specific resource, you just need to call apply_scopes
:
class GraduationsController < ApplicationController has_scope :featured, type: :boolean has_scope :by_degree has_scope :by_period, using: %i[started_at ended_at], type: :hash def index @graduations = apply_scopes(Graduation).all end end
Then for each request:
/graduations #=> acts like a normal request /graduations?featured=true #=> calls the named scope and bring featured graduations /graduations?by_period[started_at]=20100701&by_period[ended_at]=20101013 #=> brings graduations in the given period /graduations?featured=true&by_degree=phd #=> brings featured graduations with phd degree
You can retrieve all the scopes applied in one action with current_scopes
method. In the last case, it would return: { featured: true, by_degree: 'phd' }
.
Installation¶ ↑
Add has_scope
to your Gemfile or install it from Rubygems.
gem 'has_scope'
Options¶ ↑
HasScope
supports several options:
-
:type
- Checks the type of the parameter sent. By default, it does not allow hashes or arrays to be given, except if type:hash
or:array
are set. Symbols are never permitted to prevent memory leaks, so ensure any routing constraints you have that add parameters use string values. -
:only
- In which actions the scope is applied. -
:except
- In which actions the scope is not applied. -
:as
- The key in the params hash expected to find the scope. Defaults to the scope name. -
:using
- The subkeys to be used as args when type is a hash. -
:in
- A shortcut for combining the:using
option with nested hashes. -
:if
- Specifies a method or proc to call to determine if the scope should apply. Passing a string is deprecated and it will be removed in a future version. -
:unless
- Specifies a method or proc to call to determine if the scope should NOT apply. Passing a string is deprecated and it will be removed in a future version. -
:default
- Default value for the scope. Whenever supplied the scope is always called. -
:allow_blank
- Blank values are not sent to scopes by default. Set to true to overwrite.
Boolean usage¶ ↑
If type: :boolean
is set it just calls the named scope, without any arguments, when parameter is set to a “true” value. 'true'
and '1'
are parsed as true
, everything else as false
.
When boolean scope is set up with allow_blank: true
, it will call the scope with the value as any usual scope.
has_scope :visible, type: :boolean has_scope :active, type: :boolean, allow_blank: true # and models with scope :visible, -> { where(visible: true) } scope :active, ->(value = true) { where(active: value) }
Note: it is not possible to apply a boolean scope with just the query param being present, e.g. ?active
, that's not considered a “true” value (the param value will be nil
), and thus the scope will be called with false
as argument. In order for the scope to receive a true
argument the param value must be set to one of the “true” values above, e.g. ?active=true
or ?active=1
.
Block usage¶ ↑
has_scope
also accepts a block. The controller, current scope and value are yielded to the block so the user can apply the scope on its own. This is useful in case we need to manipulate the given value:
has_scope :category do |controller, scope, value| value != 'all' ? scope.by_category(value) : scope end
When used with booleans without :allow_blank
, it just receives two arguments and is just invoked if true is given:
has_scope :not_voted_by_me, type: :boolean do |controller, scope| scope.not_voted_by(controller.current_user.id) end
Keyword arguments¶ ↑
Scopes with keyword arguments need to be called in a block:
# in the model scope :for_course, lambda { |course_id:| where(course_id: course_id) } # in the controller has_scope :for_course do |controller, scope, value| scope.for_course(course_id: value) end
Apply scope on every request¶ ↑
To apply scope on every request set default value and allow_blank: true
:
has_scope :available, default: nil, allow_blank: true, only: :show, unless: :admin? # model: scope :available, ->(*) { where(blocked: false) }
This will allow usual users to get only available items, but admins will be able to access blocked items too.
Check which scopes have been applied¶ ↑
To check which scopes have been applied, you can call current_scopes
from the controller or view. This returns a hash with the scope name as the key and the scope value as the value.
For example, if a boolean :active
scope has been applied, current_scopes
will return { active: true }
.
Supported Ruby / Rails versions¶ ↑
We intend to maintain support for all Ruby / Rails versions that haven't reached end-of-life.
For more information about specific versions please check Ruby and Rails maintenance policies, and our test matrix.
Bugs and Feedback¶ ↑
If you discover any bugs or want to drop a line, feel free to create an issue on GitHub.
MIT License. Copyright 2009-2019 Plataformatec. blog.plataformatec.com.br