# Custom Controller Actions

Active Admin allows you to override and modify the underlying controller which
is generated for you. There are helpers to add collection and member actions, or
you can drop right in to the controller and modify its behavior.

## Collection Actions

A collection action is a controller action which operates on the collection of
resources. This method adds both the action to the controller as well as
generating a route for you.

To add a collection action, use the collection_action method:

```ruby
ActiveAdmin.register Post do

  collection_action :import_csv, method: :post do
    # Do some CSV importing work here...
    redirect_to collection_path, notice: "CSV imported successfully!"
  end

end
```

This collection action will generate a route at `/admin/posts/import_csv`
pointing to the `Admin::PostsController#import_csv` controller action.

## Member Actions

A member action is a controller action which operates on a single resource.

For example, to add a lock action to a user resource, you would do the
following:

```ruby
ActiveAdmin.register User do

  member_action :lock, method: :put do
    resource.lock!
    redirect_to resource_path, notice: "Locked!"
  end

end
```

This will generate a route at `/admin/users/:id/lock` pointing to the
`Admin::UserController#lock` controller action.

## HTTP Verbs

The `collection_action` and `member_action` methods both accept the `:method`
argument to set the HTTP verb for the controller action and route.

Sometimes you want to create an action with the same name, that handles multiple
HTTP verbs. In that case, this is the suggested approach:

```ruby
member_action :foo, method: [:get, :post] do
  if request.post?
    resource.update_attributes! foo: params[:foo] || {}
    head :ok
  else
    render :foo
  end
end
```

## Rendering

Custom controller actions support rendering within the standard Active Admin
layout.

```ruby
ActiveAdmin.register Post do

  # /admin/posts/:id/comments
  member_action :comments do
    @comments = resource.comments
    # This will render app/views/admin/posts/comments.html.erb
  end

end
```

If you would like to use the same view syntax as the rest of Active Admin, you
can use the Arbre file extension: .arb.

For example, create `app/views/admin/posts/comments.html.arb` with:

```ruby
table_for assigns[:post].comments do
  column :id
  column :author
  column :body do |comment|
    simple_format comment.body
  end
end
```

## Page Titles

The page title for the custom action will be the translated version of
the controller action name. For example, a member_action named "upload_csv" will
look up a translation key of `active_admin.upload_csv`. If none are found, it
defaults to the name of the controller action.

If this doesn't work for you, you can always set the `@page_title` instance
variable in your controller action to customize the page title.

```ruby
ActiveAdmin.register Post do

  member_action :comments do
    @comments   = resource.comments
    @page_title = "#{resource.title}: Comments" # Sets the page title
  end

end
```

# Action Items

To include your own action items (like the New, Edit and Delete buttons), add an
`action_item` block. The first parameter is just a name to identify the action,
and is required. For example, to add a "View on site" button to view a blog
post:

```ruby
action_item :view, only: :show do
  link_to 'View on site', post_path(post) if post.published?
end
```

Actions items also accept the `:if` option to conditionally display them:

```ruby
action_item :super_action, only: :show, if: proc{ current_admin_user.super_admin? } do
  "Only display this to super admins on the show screen"
end
```

# Modifying the Controller

The generated controller is available to you within the registration block by
using the `controller` method.

```ruby
ActiveAdmin.register Post do

  controller do
    # This code is evaluated within the controller class

    def define_a_method
      # Instance method
    end
  end

end
```