Make array like classes configurable

CHANGELOG.md

@@ -1,4 +1,8 @@
-## 1.0.0  - 2023/05/01
+## 1.1.0 - 2023/02/02
+* 🚀 [FEATURE] Allow configuring custom array-like classes to be treated as collections when serializing.  More details can be found [here](https://github.com/blueprinter-ruby/blueprinter/pull/6). Thanks to [@toddnestor](https://github.com/toddnestor).
+* 💅 [ENHANCEMENT] Reduce object allocations in fields calculations to save some memory.  More details can be found [here](https://github.com/blueprinter-ruby/blueprinter/pull/5). Thanks to [@nametoolong](https://github.com/nametoolong).
+
+## 1.0.0  - 2023/01/05
 * 🚀 [Official Release] Released [`blueprinter-rb`](https://rubygems.org/gems/blueprinter-rb) under a new organisation. More details can be found [here](https://github.com/procore/blueprinter/issues/288).
 
 ## 0.25.3  - 2021/03/03

README.md

@@ -72,6 +72,24 @@ This will result in JSON that looks something like this:
 ]
 ```
 
+
+You can also configure other classes to be treated like collections. For example, if you are using Mongoid, you can configure it to treat `Mongoid::Criteria` objects as collections:
+
+```ruby
+Blueprinter.configure do |config|
+  config.custom_array_like_classes = [Mongoid::Criteria]
+end
+```
+
+Or if you wanted it to treat the `Set` class as a collection:
+
+```ruby
+Blueprinter.configure do |config|
+  config.custom_array_like_classes = [Set]
+end
+```
+
+---
 </details>
 
 

lib/blueprinter/configuration.rb

@@ -2,7 +2,7 @@
 
 module Blueprinter
   class Configuration
-    attr_accessor :association_default, :datetime_format, :deprecations, :field_default, :generator, :if, :method, :sort_fields_by, :unless, :extractor_default, :default_transformers
+    attr_accessor :association_default, :datetime_format, :deprecations, :field_default, :generator, :if, :method, :sort_fields_by, :unless, :extractor_default, :default_transformers, :custom_array_like_classes
 
     VALID_CALLABLES = %i(if unless).freeze
 
@@ -18,6 +18,15 @@ def initialize
       @unless = nil
       @extractor_default = AutoExtractor
       @default_transformers = []
+      @custom_array_like_classes = []
+    end
+
+    def array_like_classes
+      @array_like_classes ||= [
+        Array,
+        defined?(ActiveRecord::Relation) && ActiveRecord::Relation,
+        *custom_array_like_classes
+      ].compact
     end
 
     def jsonify(blob)

lib/blueprinter/helpers/type_helpers.rb

@@ -3,13 +3,11 @@
 module Blueprinter
   module TypeHelpers
     private
-    def active_record_relation?(object)
-      !!(defined?(ActiveRecord::Relation) &&
-        object.is_a?(ActiveRecord::Relation))
-    end
 
     def array_like?(object)
-      object.is_a?(Array) || active_record_relation?(object)
+      Blueprinter.configuration.array_like_classes.any? do |klass|
+        object.is_a?(klass)
+      end
     end
   end
 end

lib/blueprinter/version.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module Blueprinter
-  VERSION = '1.0.0'
+  VERSION = '1.1.0'
 end

spec/integrations/base_spec.rb

@@ -58,6 +58,30 @@
       end
     end
 
+    context 'Given passed object is array-like' do
+      let(:blueprint) { blueprint_with_block }
+      let(:additional_object) { OpenStruct.new(obj_hash.merge(id: 2)) }
+      let(:obj) { Set.new([object_with_attributes, additional_object]) }
+
+      context 'and is an instance of a configured array-like class' do
+        before do
+          reset_blueprinter_config!
+          Blueprinter.configure { |config| config.custom_array_like_classes = [Set] }
+        end
+        after { reset_blueprinter_config! }
+
+        it 'should return the expected array of hashes' do
+          should eq('[{"id":1,"position_and_company":"Manager at Procore"},{"id":2,"position_and_company":"Manager at Procore"}]')
+        end
+      end
+
+      context 'and is not an instance of a configured array-like class' do
+        it 'should raise an error' do
+          expect { blueprint.render(obj) }.to raise_error(NoMethodError)
+        end
+      end
+    end
+
     context 'Inside Rails project' do
       include FactoryBot::Syntax::Methods
       let(:obj) { create(:user) }
@@ -383,6 +407,36 @@ def extract(association_name, object, _local_options, _options={})
           end
         end
       end
+
+      context 'Given passed object is an instance of a configured array-like class' do
+        let(:blueprint) do
+          Class.new(Blueprinter::Base) do
+            identifier :id
+            fields :make
+          end
+        end
+        let(:vehicle1) { build(:vehicle, id: 1) }
+        let(:vehicle2) { build(:vehicle, id: 2, make: 'Mediocre Car') }
+        let(:vehicle3) { build(:vehicle, id: 3, make: 'Terrible Car') }
+        let(:vehicles) { [vehicle1, vehicle2, vehicle3] }
+        let(:obj) { Set.new(vehicles) }
+        let(:result) do
+          vehicles_json = vehicles.map do |vehicle|
+            "{\"id\":#{vehicle.id},\"make\":\"#{vehicle.make}\"}"
+          end.join(',')
+          "[#{vehicles_json}]"
+        end
+
+        before do
+          reset_blueprinter_config!
+          Blueprinter.configure do |config|
+            config.custom_array_like_classes = [Set]
+          end
+        end
+        after { reset_blueprinter_config! }
+
+        it('returns the expected result') { should eq(result) }
+      end
     end
   end
   describe '::render_as_hash' do