Added policy to create

app/controllers/lessons_controller.rb

@@ -22,6 +22,7 @@ def create
     @lesson = Lesson.new(lesson_params)
     @course = Course.friendly.find(params[:course_id])
     @lesson.course_id = @course.id
+    authorize @lesson
     respond_to do |format|
       if @lesson.save
         format.html { redirect_to [ @course, @lesson ], notice: "Lesson was successfully created." }
@@ -62,6 +63,6 @@ def set_lesson
       @lesson = Lesson.friendly.find(params[:id])
     end
     def lesson_params
-      params.require(:lesson).permit(:title, :content, :course_id)
+      params.require(:lesson).permit(:title, :content)
     end
 end

app/policies/lesson_policy.rb

@@ -13,7 +13,7 @@ class Scope < ApplicationPolicy::Scope
   end
 
   def show?
-    @user.has_role?(:admin) || @record.course.user == @user.id
+    @user.has_role?(:admin) || @record.course.user_id == @user.id
   end
 
   def edit?
@@ -25,9 +25,11 @@ def update?
   end
 
   def new?
+    # @record.course.user_id == @user.id
   end
 
   def create?
+    @record.course.user_id == @user.id
   end
 
   def destroy?

app/views/courses/show.html.haml

@@ -6,6 +6,8 @@
   .col-lg-6
     = render 'courses/course', course: @course
   .col-lg-6
-    = link_to 'Add lesson', new_course_lesson_path(@course, @lesson)
+    -if policy(@course).edit?
+      = link_to "Add lesson", new_course_lesson_path(@course, @lesson), class: "d-flex justify-content-center btn btn-primary"
+    %p 
     - @lessons.each do |lesson|
-      = render 'lessons/lesson', lesson: lesson
+      = render "lessons/lesson", lesson: lesson

app/views/lessons/_form.html.haml

@@ -7,10 +7,11 @@
     = f.input :title
     = f.label :content
     = f.rich_text_area :content
+    %small= f.error :content, class: "text-danger"
     -# como estaba 
     -# = f.association :course
     -# Esto de abajo asigno el input del html por defecto si ya es un lesson o por params. as: :hidden hide the input
     -# = f.input :course_id, input_html: {value: @course.id || params[:course_id]}, as: :hidden
 
   .form-actions
-    = f.button :submit
+    = f.button :submit, {class: "btn btn-success mb-2 mt-2"}

app/views/lessons/new.html.haml

@@ -2,4 +2,4 @@
 
 = render 'form'
 
-= link_to 'Back', course_path(@course)
+= link_to 'Back to course', course_path(@course)