Add GlobalId::Identification::build_global_id

lib/global_id/identification.rb

@@ -116,5 +116,35 @@ def to_signed_global_id(options = {})
     def to_sgid_param(options = {})
       to_signed_global_id(options).to_param
     end
+
+    class << self
+      def included(base)
+        base.extend(ClassMethods)
+      end
+    end
+
+    module ClassMethods
+      # Build a Global ID from the given object.
+      #
+      # If the object responds to `to_global_id` it will return the result of that call.
+      #   Person.build_global_id(Person.find(1)) # => #<GlobalID:0x000000012b7dcea0 @uri=#<URI::GID gid://app/Person/1>>
+      # If the object is a string or an integer, it will build a GlobalID using that object.
+      #   Person.build_global_id(1) # => #<GlobalID:0x000000012b7dcea0 @uri=#<URI::GID gid://app/Person/1>>
+      # If the object is not a string or an integer, it will raise an ArgumentError.
+      #   Person.build_global_id(Person) # => ArgumentError: Can't build a Global ID for Class
+      #
+      # An app is required to create a GlobalID. Pass the :app option or set the default GlobalID.app.
+
+      def build_global_id(obj, options = {})
+        return obj.to_global_id(options) if obj.respond_to?(:to_global_id)
+        raise ArgumentError, "Can't build a Global ID for #{obj.class}" unless obj.is_a?(String) || obj.is_a?(Integer)
+
+        unless (app = options.fetch(:app) { GlobalID.app })
+          raise ArgumentError, "An app is required to create a GlobalID. Pass the :app option or set the default GlobalID.app."
+        end
+
+        GlobalID.new(URI::GID.build(app: app, model_name: name, model_id: obj, params: options.except(:app, :verifier, :for)))
+      end
+    end
   end
 end

test/cases/global_identification_test.rb

@@ -8,11 +8,15 @@ class GlobalIdentificationTest < ActiveSupport::TestCase
   test 'creates a Global ID from self' do
     assert_equal GlobalID.create(@model), @model.to_global_id
     assert_equal GlobalID.create(@model), @model.to_gid
+    assert_equal PersonModel.build_global_id(@model), @model.to_gid
+    assert_equal PersonModel.build_global_id(1), @model.to_global_id
   end
 
   test 'creates a Global ID with custom params' do
     assert_equal GlobalID.create(@model, some: 'param'), @model.to_global_id(some: 'param')
     assert_equal GlobalID.create(@model, some: 'param'), @model.to_gid(some: 'param')
+    assert_equal PersonModel.build_global_id(@model, some: 'param'), @model.to_gid(some: 'param')
+    assert_equal PersonModel.build_global_id(1, some: 'param'), @model.to_global_id(some: 'param')
   end
 
   test 'creates a signed Global ID from self' do
@@ -30,6 +34,10 @@ class GlobalIdentificationTest < ActiveSupport::TestCase
     assert_equal SignedGlobalID.create(@model, some: 'param'), @model.to_sgid(some: 'param')
   end
 
+  test "doesn't create a Global ID if ID is not valid" do
+    assert_raises(ArgumentError) { PersonModel.build_global_id(PersonModel) }
+  end
+
   test 'dup should clear memoized to_global_id' do
     global_id = @model.to_global_id
     dup_model = @model.dup