= Presenters

There are more types of presenters, that Decidim is using:

- ResourcePresenter - This presenter type is used to ensure consistency by properly format the resource in the views, like creating links to the resource, formatting or escaping the resource texts, ensure the references are being correctly represented.
- AdminLogPresenter - This presenter type is used to properly display the resource in the admin area, so that Decidim is able to display any changes done on a resource, or provide additional links, etc.

== ResourcePresenter

This presenter is used to show in the views the resource.

The presenter classes are located in the `app/presenter/decidim/<my_module>/` directory, and named: `<my_resource>_presenter.rb`.

If you need to use this, you can add in your model a method like this:

``` ruby
# Returns the presenter for this author, to be used in the views.
# Required by ResourceRenderer.
def presenter
  Decidim::MyModule::MyResourcePresenter.new(self)
end

```

Then, you can implement the presenter like this:

```ruby
# frozen_string_literal: true

# app/presenters/decidim/my_module/my_resource_presenter.rb
module Decidim
  module MyModule
    class MyResourcePresenter < Decidim::ResourcePresenter
    end
  end
end
```


== AdminLogPresenter

This presenter is used to show the admin log in the admin panel.

The presenter classes are located in the `app/presenter/decidim/<my_module>/admin_log` directory, and named: `<my_resource>_presenter.rb`.

If you need to use this, you can add in your model a method like this:

```ruby
def self.log_presenter_class_for(_log)
  Decidim::MyModule::AdminLog::MyResourcePresenter
end
```

Then, you can implement the presenter like this:

```ruby
# frozen_string_literal: true

# app/presenters/decidim/my_module/admin_log/my_resource_presenter.rb
module Decidim
  module MyModule
    module AdminLog
      class MyResourcePresenter < Decidim::Log::BasePresenter

        # This is the list of field types that we want to show in the admin log, in the revision history
        def diff_fields_mapping
          {
            title: :i18n,
            some_field: :boolean,
            some_other_field: :string
          }
        end

        # This is the i18n key that we are using to load any strings
        def i18n_labels_scope
          "activemodel.attributes.my_resource"
        end

        def action_string
          case action
          when "publish"
            "decidim.my_module.admin_log.my_resource.#{action}"
          else
            super
          end
        end
      end
    end
  end
end
```

When handling custom events, like `publish`, you need to add the translation to the `decidim.my_module.admin_log.my_resource` scope.
You will also need to use a command to handle the event, having a method like this:

```ruby
# frozen_string_literal: true

# app/commands/decidim/my_module/publish_my_resource.rb
module Decidim
  module MyModule
    # A command with the business logic to invite an user to an organization.
    class PublishMyResource < Decidim::Command
      # Public: Initializes the command.
      #
      # form
      # resource
      def initialize(resource, current_user)
        @resource = resource
        @current_user = current_user
      end

      def call
        return broadcast(:invalid) unless resource.condition?

        Decidim.traceability.perform_action!(
          "publish",
          @resource,
          @current_user
        ) do
          resource.publish!
        end

        broadcast(:ok)
      end
    end
  end
end
```