Encapsulate serialization in ActiveModel::SerializableResource

Usage: ActiveModel::SerializableResource.serialize(resource, options)

lib/active_model/serializable_resource.rb

@@ -0,0 +1,82 @@
+require "set"
+module ActiveModel
+  class SerializableResource
+
+    ADAPTER_OPTION_KEYS = Set.new([:include, :fields, :adapter])
+
+    def initialize(resource, options = {})
+      @resource = resource
+      @adapter_opts, @serializer_opts =
+        options.partition { |k, _| ADAPTER_OPTION_KEYS.include? k }.map { |h| Hash[h] }
+    end
+
+    delegate :serializable_hash, :as_json, :to_json, to: :adapter
+
+    # Primary interface to building a serializer (with adapter)
+    # If no block is given,
+    # returns the serializable_resource, ready for #as_json/#to_json/#serializable_hash.
+    # Otherwise, yields the serializable_resource and
+    # returns the contents of the block
+    def self.serialize(resource, options = {})
+      serializable_resource = SerializableResource.new(resource, options)
+      if block_given?
+        yield serializable_resource
+      else
+        serializable_resource
+      end
+    end
+
+    def serialization_scope=(scope)
+      serializer_opts[:scope] = scope
+    end
+
+    def serialization_scope
+      serializer_opts[:scope]
+    end
+
+    def serialization_scope_name=(scope_name)
+      serializer_opts[:scope_name] = scope_name
+    end
+
+    def adapter
+      @adapter ||= ActiveModel::Serializer::Adapter.create(serializer_instance, adapter_opts)
+    end
+    alias_method :adapter_instance, :adapter
+
+    def serializer_instance
+      @serializer_instance ||= serializer.new(resource, serializer_opts)
+    end
+
+    # Get serializer either explicitly :serializer or implicitly from resource
+    # Remove :serializer key from serializer_opts
+    # Replace :serializer key with :each_serializer if present
+    def serializer
+      @serializer ||=
+        begin
+          @serializer = serializer_opts.delete(:serializer)
+          @serializer ||= ActiveModel::Serializer.serializer_for(resource)
+
+          if serializer_opts.key?(:each_serializer)
+            serializer_opts[:serializer] = serializer_opts.delete(:each_serializer)
+          end
+          @serializer
+        end
+    end
+    alias_method :serializer_class, :serializer
+
+    # True when no explicit adapter given, or explicit appear is truthy (non-nil)
+    # False when explicit adapter is falsy (nil or false)
+    def use_adapter?
+      !(adapter_opts.key?(:adapter) && !adapter_opts[:adapter])
+    end
+
+    def serializer?
+      use_adapter? && !!(serializer)
+    end
+
+    private
+
+    attr_reader :resource, :adapter_opts, :serializer_opts
+
+  end
+end