Module: NextPage::Pagination

Extended by:
ActiveSupport::Concern
Defined in:
lib/next_page/pagination.rb

Overview

Pagination

Module Pagination provides pagination for index methods. It assigns a limit and offset to the resource query and extends the relation with mixin NextPage::PaginationAttributes.

There are two ways to paginate: using a before filter or by calling ‘paginate_resource` explicitly.

Before Filter

Here’s an example of using the before filter in a controller:

before_action :apply_next_page_pagination, only: :index

This entry point uses the following conventions to apply pagination:

  • the name of the instance variable is the same as the component (for example PhotosController -> @photos)

  • the name of the model is the controller name singularized (for example PhotosController -> Photo)

Either can be overridden by calling method ‘paginate_with` in the controller. The two override options are `instance_variable_name` and `model_class`. For example, if the PhotosController used the model Picture and the instance variable name @photographs, the controller declares it as follows:

paginate_with instance_variable_name: :photographs, model_class: 'Picture'

If the before filter is used, it will populate an instance variable. The action should NOT reset the variable, as that removes pagination.

Invoking Pagination Directly

To paginate a resource pass the resource into method ‘paginate_resource` then store the return value back in the resource:

@photos = paginate_resource(@photos)

Default Limit

The default size limit can be overridden with the ‘paginate_with` method for either type of pagination. Pass option `default_limit` to specify an override:

paginate_with default_limit: 25

All the options can be mixed and matches when calling ‘paginate_with`:

paginate_with model_class: 'Photo', default_limit: 12
paginate_with default_limit: 12, instance_variable_name: 'data'

Instance Method Summary collapse

Instance Method Details

#apply_next_page_pagination ⇒ Object

Called with before_action in order to automatically paginate the resource.



62
63
64
 
# File 'lib/next_page/pagination.rb', line 62

def apply_next_page_pagination
  self.class.next_page_paginator.paginate(self, params.slice(:page, :sort))
end

#paginate_resource(resource) ⇒ Object

Invokes pagination directly, the result must be stored as the resource itself is not modified.



67
68
69
 
# File 'lib/next_page/pagination.rb', line 67

def paginate_resource(resource)
  self.class.next_page_paginator.paginate_resource(resource, params.slice(:page, :sort))
end

#render(*args) ⇒ Object

:nodoc:



71
72
73
74
75
76
77
78
79
80
 
# File 'lib/next_page/pagination.rb', line 71

def render(*args) #:nodoc:
  return super unless action_name == 'index' && request.headers[:Accept] == 'application/vnd.api+json'

  options = args.first
  return super unless options.is_a?(Hash) && options.key?(:json)

  options[:meta] = options.fetch(:meta, {}).merge!(total_pages: options[:json].total_pages,
                                                   total_count: options[:json].total_count)
  super
end