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name: plutonium-nested-resources description: Plutonium nested resources - parent/child routes, scoping, and URL generation

Nested Resources

Plutonium automatically creates nested routes for has_many and has_one associations, scopes queries to the parent, and handles URL generation.

How It Works

When you register resources with parent-child relationships:

Copy# In portal routes
register_resource ::Company
register_resource ::Property  # has belongs_to :company
register_resource ::CompanyProfile  # has belongs_to :company (has_one on Company)

Plutonium automatically creates nested routes with a nested_ prefix:

• /companies/:company_id/nested_properties - Properties scoped to company (has_many)
• /companies/:company_id/nested_properties/new - New property for company
• /companies/:company_id/nested_properties/:id - Property in company context
• /companies/:company_id/nested_company_profile - Singular profile (has_one)
• /companies/:company_id/nested_company_profile/new - New profile for company

The nested_ prefix prevents route conflicts when the same resource is registered both as a top-level and nested resource.

Automatic Behavior

When accessing nested routes, Plutonium automatically:

1. Resolves the parent via current_parent
2. Scopes queries to only show records belonging to parent
3. Assigns parent to new records on create
4. Hides parent field in forms (already determined by URL)
5. Authorizes parent access before proceeding

Controller Methods

current_parent

Returns the parent record from the URL:

Copy# URL: /companies/123/properties
current_parent  # => Company.find(123)

parent_route_param

The URL parameter containing the parent ID:

Copyparent_route_param  # => :company_id

parent_input_param

The association name on the child model:

Copyparent_input_param  # => :company

Presentation Hooks

Control whether parent field appears in views/forms:

Copyclass PropertiesController < ResourceController
  private

  # Show parent field in displays (default: false)
  def present_parent?
    true
  end

  # Allow changing parent in forms (default: same as present_parent?)
  def submit_parent?
    false  # Parent is set from URL, don't allow changing
  end
end

Query Scoping

Collections are automatically scoped to the parent via policies. The policy receives parent and parent_association context:

Copyclass PropertyPolicy < ResourcePolicy
  # parent: the parent record (e.g., Company instance)
  # parent_association: the association name (e.g., :properties)

  relation_scope do |relation|
    relation = super(relation)  # Applies parent scoping automatically
    relation
  end
end

How Parent Scoping Works

For has_many associations, scoping uses the association directly:

Copy# parent.properties => Company#properties
parent.send(parent_association)

For has_one associations, scoping uses a where clause:

Copy# Property.where(company_id: company.id) with limit
relation.where(foreign_key => parent.id)

Parent vs Entity Scope

When a parent is present, parent scoping takes precedence over entity scoping:

Copy# With parent: scopes via parent association
# Without parent: falls back to entity_scope (multi-tenancy)

This prevents double-scoping - the parent was already authorized and entity-scoped during its own authorization.

Custom Association Scope

For complex relationships, define a custom scope:

Copyclass Property < ResourceRecord
  scope :associated_with_organization, ->(org) {
    joins(:company).where(companies: { organization_id: org.id })
  }
end

URL Generation

Use resource_url_for with the parent: option:

Copy# Child collection (has_many)
resource_url_for(Property, parent: company)
# => /companies/123/nested_properties

# Child record
resource_url_for(property, parent: company)
# => /companies/123/nested_properties/456

# New child form
resource_url_for(Property, action: :new, parent: company)
# => /companies/123/nested_properties/new

# Edit child
resource_url_for(property, action: :edit, parent: company)
# => /companies/123/nested_properties/456/edit

# Singular resource (has_one)
resource_url_for(company_profile, parent: company)
# => /companies/123/nested_company_profile

resource_url_for(CompanyProfile, action: :new, parent: company)
# => /companies/123/nested_company_profile/new

Cross-Package URL Generation

Generate URLs for resources in a different package:

Copy# From AdminPortal, generate URL to CustomerPortal resource
resource_url_for(property, parent: company, package: CustomerPortal)

Association Panels

On the parent's show page, child resources are displayed via association panels:

Copyclass CompanyPolicy < ResourcePolicy
  def permitted_associations
    %i[properties contacts]  # Shows panels for these
  end
end

The panel loads children via the nested route automatically.

Authorization

Parent Authorization

The parent is authorized for :read? before current_parent returns:

Copydef current_parent
  # ... resolution logic ...
  authorize! parent, to: :read?
  parent
end

Policy Context

The parent is passed to child policies as entity_scope:

Copyclass PropertyPolicy < ResourcePolicy
  def create?
    # entity_scope is the parent company
    entity_scope.present? && user.member_of?(entity_scope)
  end

  def read?
    entity_scope.present? && record.company == entity_scope
  end
end

Parameter Handling

Parent is automatically injected into resource params:

Copy# When creating a property under /companies/123/properties
resource_params
# => { name: "...", company: <Company:123>, company_id: 123 }

You don't need to include hidden fields for the parent in forms.

has_one Associations

Plutonium supports both has_many and has_one associations:

Copyclass Company < ResourceRecord
  has_many :properties           # Plural routes
  has_one :company_profile       # Singular routes
end

Routes generated:

• has_many: /companies/:id/nested_properties (plural, with :id param)
• has_one: /companies/:id/nested_company_profile (singular, no :id param)

For has_one associations:

• Index redirects to show (or new if no record exists)
• Only one record can exist per parent
• Forms don't show parent field (determined by URL)

Nesting Limitations

Plutonium supports one level of nesting:

• ✅ /companies/:company_id/nested_properties (parent → child)
• ❌ /companies/:company_id/nested_properties/:property_id/nested_units (grandparent → parent → child)

Common Patterns

Scoped Uniqueness

Validate uniqueness within parent:

Copyclass Property < ResourceRecord
  belongs_to :company
  validates :code, uniqueness: { scope: :company_id }
end

Conditional Parent Display

Show parent only in certain contexts:

Copyclass PropertiesController < ResourceController
  private

  def present_parent?
    # Show parent when accessed standalone, hide when nested
    current_parent.nil?
  end
end

Custom Parent Resolution

Override parent lookup:

Copyclass PropertiesController < ResourceController
  private

  def current_parent
    @current_parent ||= Company.friendly.find(params[:company_id])
  end
end

Breadcrumbs

Breadcrumbs automatically include the parent:

CopyCompanies > Acme Corp > Properties > Property #123

Route Registration with Custom Routes

Add custom member/collection routes to nested resources:

Copyregister_resource ::Property do
  member do
    get :analytics
    post :archive
  end
end

Generates nested routes:

• /companies/:company_id/properties/:id/analytics
• /companies/:company_id/properties/:id/archive

Related Skills

• plutonium-portal - Route registration
• plutonium-policy - Authorization and scoping
• plutonium-controller - Presentation hooks
• plutonium-model-features - associated_with scope