Validations: Default context based on persistence

This commit proposed that Active Resource follow the same pattern as
[Active Record Validations][], namely that an instance's default
validation context will be `:create` when the record **is not yet**
persisted and `:update` when the record **is** persisted.

[Active Record Validations]: https://api.rubyonrails.org/v8.1/classes/ActiveRecord/Validations.html#method-i-valid-3F

Author: seanpdoyle

lib/active_resource/validations.rb

@@ -314,6 +314,14 @@ def load_remote_errors(remote_errors, save_cache = false) # :nodoc:
     # saved.
     # Remote errors can only be cleared by trying to re-save the resource.
     #
+    # If the argument is +false+ (default is +nil+), the context is set to <tt>:create</tt> if
+    # {new_record?}[rdoc-ref:Base#new_record?] is +true+, and to <tt>:update</tt> if it is not.
+    # If the argument is an array of contexts, <tt>post.valid?([:create, :update])</tt>, the validations are
+    # run within multiple contexts.
+    #
+    # \Validations with no <tt>:on</tt> option will run no matter the context. \Validations with
+    # some <tt>:on</tt> option will only run in the specified context.
+    #
     # ==== Examples
     #   my_person = Person.create(params[:person])
     #   my_person.valid?
@@ -324,6 +332,8 @@ def load_remote_errors(remote_errors, save_cache = false) # :nodoc:
     #   # => false
     #
     def valid?(context = nil)
+      context ||= new_record? ? :create : :update
+
       run_callbacks :validate do
         super
         load_remote_errors(@remote_errors, true) if defined?(@remote_errors) && @remote_errors.present?

test/cases/validations_test.rb

@@ -8,6 +8,13 @@
 # This test case simply makes sure that they are all accessible by
 # Active Resource objects.
 class ValidationsTest < ActiveSupport::TestCase
+  class DraftProject < ::Project
+    self.element_name = "project"
+
+    validates :name, format: { with: /\ACREATE:/, on: :create }
+    validates :name, format: { with: /\AUPDATE:/, on: :update }
+  end
+
   VALID_PROJECT_HASH = { name: "My Project", description: "A project" }
   def setup
     @my_proj = { "person" => VALID_PROJECT_HASH }.to_json
@@ -38,6 +45,33 @@ def test_save_with_context
     assert_equal [ "can't be blank" ], p.errors.messages_for(:summary)
   end
 
+  def test_save_with_default_create_context
+    p = DraftProject.new VALID_PROJECT_HASH.merge(name: "Invalid")
+    assert_not p.save
+    assert_equal [ "is invalid" ], p.errors.messages_for(:name)
+
+    p.name = "CREATE: Valid"
+    assert p.save, "should save"
+    assert_empty p.errors
+  end
+
+  def test_save_with_default_update_context
+    attributes = VALID_PROJECT_HASH.merge(id: 1, name: "CREATE: Created")
+
+    ActiveResource::HttpMock.respond_to do |mock|
+      mock.get "/projects/1.json", {}, attributes.to_json
+      mock.put "/projects/1.json", {}, attributes.to_json
+    end
+
+    p = DraftProject.find(1)
+    assert_not p.save
+    assert_equal [ "is invalid" ], p.errors.messages_for(:name)
+
+    p.name = "UPDATE: Updated"
+    assert p.save, "should save"
+    assert_empty p.errors
+  end
+
   def test_save_bang_with_context
     p = new_project(summary: nil)
     assert_raise(ActiveResource::ResourceInvalid) { p.save!(context: :completed) }