Add Assignable helper

Author: bradgessler

app/controllers/oxidizer/assignable.rb

@@ -0,0 +1,98 @@
+module Oxidizer
+  module Assignable
+    extend ActiveSupport::Concern
+
+    included do
+      class_attribute :model, :parent_model, :context_method_name
+
+      before_action :assign_parent_collection, if: :has_parent_model?
+      before_action :assign_parent_member, if: :has_parent_model?
+      before_action :assign_collection
+      before_action :assign_member
+    end
+
+    def assign_collection
+      instance_variable_set "@#{model.model_name.plural}", model_scope
+    end
+
+    def assign_parent_collection
+      instance_variable_set "@#{parent_model.model_name.plural}", parent_model_scope
+    end
+
+    def model_scope
+      if has_parent_model?
+        parent_model_instance.association(model.model_name.collection)
+      elsif has_assignable_context?
+        assignable_context.association(model.model_name.collection).scope
+      else
+        model.scope_for_association
+      end
+    end
+
+    def parent_model_scope
+      if has_assignable_context?
+        assignable_context.association(parent_model.model_name.collection)
+      else
+        parent_model.scope_for_association
+      end
+    end
+
+    def parent_model_instance
+      parent_model_scope.find(params.fetch(parent_model_param_key))
+    end
+
+    def assign_parent_member
+      instance_variable_set "@#{parent_model.model_name.singular}", parent_model_instance
+    end
+
+    def has_parent_model?
+      parent_model.present?
+    end
+
+    def assign_member
+      instance_variable_set "@#{model.model_name.singular}", model_instance
+    end
+
+    def model_instance
+      if member?
+        model_scope.find params.fetch(model_param_key)
+      else
+        model_scope.build
+      end
+    end
+
+    def member?
+      params.key? model_param_key
+    end
+
+    def model_param_key
+      :id
+    end
+
+    def parent_model_param_key
+      "#{parent_model.model_name.singular}_id".to_sym
+    end
+
+    def assignable_context
+      self.send self.class.context_method_name
+    end
+
+    def has_assignable_context?
+      if self.class.context_method_name
+        self.respond_to? self.class.context_method_name
+      end
+    end
+
+    class_methods do
+      def assign(scope, through: nil, from: nil)
+        self.model = Assignable.find_scope scope
+        self.parent_model = Assignable.find_scope through
+        self.context_method_name = from
+      end
+    end
+
+    def self.find_scope(name)
+      name.to_s.singularize.camelize.constantize if name
+    end
+  end
+end