Validate presence of `notes.content`

This commit adds both model and controller coverage for validating that Note model is created with its required fields.

Extends the Note model to use the validates_presence_of validator by passing presence: true to the validates macro.

When validating a record without a content field, the presence: true validation’s failure supersedes the previous behavior of violating the column’s NOT NULL constraint and raising a ActiveRecord::NotNullViolation error. Since the two are not compatible, this commit removes the previous test coverage from notes_test.rb.

When responding to a POST /notes request that would result in an invalid Note record, our controller will re-render the notes#new to present the client with another opportunity to submit a Note. In addition, the controller will respond with a 422 HTTP Status to indicate to the client that the previous request was unprocessable entity.


      app/controllers/notes_controller.rb

diff --git a/app/controllers/notes_controller.rb b/app/controllers/notes_controller.rb
index 7534670..8375672 100644
--- a/app/controllers/notes_controller.rb
+++ b/app/controllers/notes_controller.rb
@@ -8,8 +8,18 @@ class NotesController < ApplicationController
   end
 
   def create
-    note = Note.create!(params.to_unsafe_h.slice(:content))
+    note = Note.new(note_params)
 
-    redirect_to notes_url
+    if note.save
+      redirect_to notes_url
+    else
+      render(:new, status: :unprocessable_entity)
+    end
+  end
+
+  private
+
+  def note_params
+    params.to_unsafe_h.slice(:content)
   end
 end


      app/models/note.rb

diff --git a/app/models/note.rb b/app/models/note.rb
index b6b1e5a..67129f0 100644
--- a/app/models/note.rb
+++ b/app/models/note.rb
@@ -1,2 +1,3 @@
 class Note < ApplicationRecord
+  validates :content, presence: true
 end


      test/controllers/notes_controller_test.rb

diff --git a/test/controllers/notes_controller_test.rb b/test/controllers/notes_controller_test.rb
index eebcb0a..2d64375 100644
--- a/test/controllers/notes_controller_test.rb
+++ b/test/controllers/notes_controller_test.rb
@@ -10,10 +10,18 @@ class NotesControllerTest < ActionDispatch::IntegrationTest
   end
 
   test "#create redirects to /notes" do
-    notes_attributes = { content: "Hello, World" }
+    note_attributes = { content: "Hello, World" }
 
-    post notes_path, params: notes_attributes
+    post notes_path, params: note_attributes
 
     assert_redirected_to notes_url
   end
+
+  test "#create with invalid data responds with unprocessable entity" do
+    note_attributes = {}
+
+    post notes_path, params: note_attributes
+
+    assert_response :unprocessable_entity
+  end
 end


      test/models/note_test.rb

diff --git a/test/models/note_test.rb b/test/models/note_test.rb
index 42a53e2..679348d 100644
--- a/test/models/note_test.rb
+++ b/test/models/note_test.rb
@@ -1,11 +1,12 @@
 require 'test_helper'
 
 class NoteTest < ActiveSupport::TestCase
-  test "NOT NULL database constraint on notes.content" do
+  test "validates content is present" do
     note = Note.new
 
-    exercise = -> { note.save! }
+    valid = note.validate
 
-    assert_raises(ActiveRecord::NotNullViolation, /content/, &exercise)
+    assert_equal valid, false
+    assert_equal note.errors[:content], [I18n.translate("errors.messages.blank")]
   end
 end

Validate presence of notes.content

Validate presence of `notes.content`