ruby on rails - NoMethodError in Student#categories -

showing /home/ns/school/app/views/student/_student_category_list.erb line #4 raised:

undefined method `each' nil:nilclass

<ul id="category-list">               <% @student_categories.each |c| %>                  <li class="list<%=cycle('odd', 'even')%>">                     <div class="category-name"><%= c.name %></div>                     <div class="category-edit"><%= link_to "#{t('edit_text')}", :url => { :action => 'category_edit', :id => c.id } %>                      </div>                     <div class="category-delete"><%= link_to  "#{t('delete_text')}", :url => { :action => 'category_delete', :id => c.id } , :confirm =>"#{t('delete_confirm_msg')}"%>                     </div>                 </li>             <% end %>      </ul> 

essentially, needs see controller code, because want ensure instance variable @student_categories contains hash of data.

however, can infer @student_categories either:

1. not being initialized in controller @ all, result in error.
2. not being initialized in correct controller action.
3. is being misspelled @student_category/@student_categories someplace in code, (rails pluralization can confusing @ first.)

solution:

• check model named student_category.rb or student.rb
• check controller named student_categories_controller.rb or students.rb

since listing of categories, i'm going assume @student_categories variable found in index action, within student_categories_controller.rb in case student_category_list action.

adjust appropriately.

class studentcategoriescontroller < applicationcontroller   def student_categories_list     # action     end end 

you should have index action in controller, this:

def index   @student_categories = studentcategory.all # not production end 

or maybe, looks this:

def index   @student_category = studentcategory.all # not production end 

perhaps looks this:

def index   @student_categories = student.all # not production end 

with model, view, , controller code, give exact solution, 99% of time it's problem pluralization. rails has naming conventions should at.

also, careful using model.all in production, since there tens of thousands of records in model.