Add partials

Signed-off-by: Jordan Hollinger <[email protected]>

lib/blueprinter.rb

@@ -8,6 +8,7 @@ module Blueprinter
   autoload :Extension, 'blueprinter/extension'
   autoload :Transformer, 'blueprinter/transformer'
   autoload :V2, 'blueprinter/v2'
+  autoload :V3, 'blueprinter/v3'
 
   class << self
     # @return [Configuration]

lib/blueprinter/errors.rb

@@ -3,6 +3,7 @@
 module Blueprinter
   module Errors
     autoload :InvalidBlueprint, 'blueprinter/errors/invalid_blueprint'
+    autoload :UnknownPartial, 'blueprinter/errors/unknown_partial'
     autoload :UnknownView, 'blueprinter/errors/unknown_view'
   end
 end

lib/blueprinter/errors/unknown_partial.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+module Blueprinter
+  module Errors
+    class UnknownPartial < Blueprinter::BlueprinterError; end
+  end
+end

lib/blueprinter/v2.rb

@@ -11,13 +11,14 @@ class V2
     extend Reflection
 
     class << self
-      attr_accessor :views, :fields, :extensions, :options
+      attr_accessor :views, :fields, :partials, :extensions, :options
       # The fully-qualified name, e.g. "MyBlueprint", or "MyBlueprint.foo.bar"
       attr_accessor :blueprint_name
     end
 
     self.views = {}
     self.fields = {}
+    self.partials = {}
     self.extensions = []
     self.options = Options.new(DEFAULT_OPTIONS)
     self.blueprint_name = name
@@ -26,6 +27,7 @@ class << self
     def self.inherited(subclass)
       subclass.views = { default: subclass }
       subclass.fields = fields.transform_values(&:dup)
+      subclass.partials = partials.dup
       subclass.extensions = extensions.dup
       subclass.options = options.dup
       subclass.blueprint_name = subclass.name || blueprint_name

lib/blueprinter/v2/dsl.rb

@@ -23,6 +23,30 @@ def view(name, &definition)
         views[name.to_sym] = view
       end
 
+      #
+      # Define a new partial.
+      #
+      # @param name [Symbol] Name of the partial to create or import
+      # @yield Define a new partial in the block
+      #
+      def partial(name, &definition)
+        partials[name.to_sym] = definition
+      end
+
+      #
+      # Import a partial into this view.
+      #
+      # @param name [Array<Symbol>] One or more partial names
+      #
+      def use(*names)
+        names.each do |name|
+          if !(p = partials[name])
+            raise Errors::UnknownPartial, "Partial '#{name}' could not be found in Blueprint '#{self}'. NOTE: partials must be defined before your views!"
+          end
+          class_eval(&p)
+        end
+      end
+
       #
       # Define a field.
       #
@@ -67,7 +91,11 @@ def association(name, blueprint, from: name, view: nil, **options, &definition)
         )
       end
 
-      # Exclude parent fields/associations from inheritance
+      #
+      # Exclude parent fields and associations from this view.
+      #
+      # @param name [Array<Symbol>] One or more fields or associations to exclude
+      #
       def exclude(*names)
         unknown = []
         names.each do |name|

spec/v2/partials_spec.rb

@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+describe "Blueprinter::V2 Partials" do
+  it "should allow a partial to be used in any view" do
+    blueprint = Class.new(Blueprinter::V2) do
+      field :name
+
+      partial :description do
+        field :description
+      end
+
+      view :foo do
+        use :description
+      end
+
+      view :bar do
+        use :description
+      end
+    end
+
+    expect(blueprint.reflections[:default].fields.keys).to eq %i(name)
+    expect(blueprint.reflections[:foo].fields.keys.sort).to eq %i(
+      name
+      description
+    ).sort
+    expect(blueprint.reflections[:bar].fields.keys.sort).to eq %i(
+      name
+      description
+    ).sort
+  end
+
+  it "should throw an error for an invalid partial name" do
+    expect do
+      Class.new(Blueprinter::V2) do
+        view :foo do
+          use :description
+        end
+      end
+    end.to raise_error(Blueprinter::Errors::UnknownPartial)
+  end
+end