draper-decorators

# Draper Decorators for Rails

This skill provides guidance for creating effective Draper decorators in Rails applications.

## Philosophy

Decorators implement separation of concerns between **business logic** (models) and **presentation logic** (views). A decorator wraps a model to add view-specific methods without polluting the model.

**What belongs in decorators:**
- Date/time formatting (`created_at.strftime("%B %d, %Y")`)
- String concatenation (`"#{first_name} #{last_name}"`)
- HTML generation (`h.content_tag(:span, status, class: css_class)`)
- Conditional rendering based on state
- Number formatting (currency, percentages)
- CSS class generation based on object state

**What does NOT belong in decorators:**
- Business logic (validations, calculations, state changes)
- Database queries (use includes in controllers)
- Anything not directly related to presentation

## Basic Structure

```ruby
# app/decorators/user_decorator.rb
class UserDecorator < ApplicationDecorator
  delegate_all

  def full_name
    "#{first_name} #{last_name}"
  end

  def formatted_created_at
    created_at.strftime("%B %d, %Y")
  end

  def status_badge
    css_class = active? ? "badge-success" : "badge-secondary"
    h.content_tag(:span, status, class: "badge #{css_class}")
  end
end
```

## Delegation Strategies

### Option 1: `delegate_all` (Convenient)

Delegates all methods to the wrapped object via `method_missing`. Use for most decorators.

```ruby
class ProductDecorator < ApplicationDecorator
  delegate_all

  def formatted_price
    h.number_to_currency(price)
  end
end
```

### Option 2: Explicit Delegation (Strict)

Explicitly declare which methods to delegate. Use for larger apps where control matters.

```ruby
class ProductDecorator < ApplicationDecorator
  delegate :id, :name, :price, :created_at, :persisted?

  def formatted_price
    h.number_to_currency(price)
  end
end
```

## Accessing the Wrapped Object

Three equivalent ways to access the model:

```ruby
class Art