rails カテゴリー機能　追加ボタンを押しても追加されない

### index.html.erb

<%= content_tag :div, nil, class: 'row' do %>
  <%= content_tag :div, nil, class: 'col-xs-3' do %>
    <%= form_with model: @category, local: true do |f| %>
      <%= f.label :name, '｜カテゴリー名' %>
      <%= content_tag :br %>
      <%= f.text_field :name, class: 'form-control' %>
      <%= content_tag :br %>
      <%= f.submit '追加', class: 'btn btn-primary btn-block' %>
    <% end %>
  <% end %>

  <%= content_tag :div, nil, class: 'col-xs-9' do %>
    <%= content_tag :table, nil, class: 'table' do %>
      <%= content_tag :thead do %>
        <%= content_tag :tr %>
          <%= content_tag :th %>
            ｜カテゴリー名
          <%= content_tag :th %>
          <%= content_tag :th %>
      <% end %>
      <%= content_tag :tbody do %>

        <% @categories.each do |category| %>
          <%= content_tag :tr %>
            <%= content_tag :td %>
              <%= category.name %>
            <%= content_tag :td %>
              <%= link_to '編集', edit_category_path(category), class: 'btn-sm btn-primary' %>
            <%= content_tag :td %>
              <%= link_to '削除', category_path(category), method: :delete, data: 
              {confirm: '本当に削除しますか？'}, class: 'btn-sm btn-danger' %>
        <% end %>
      <% end %>
    <% end %>
  <% end %>
<% end %>

###categories_controller.rb

class CategoriesController < ApplicationController
  before_action :set_category, only: [:edit, :update, :destroy]

  def index
    @category = Category.new
    @categories = Category.all
  end

  def create 
    @category = Category.new(category_params)
    if @category.save
      redirect_to categories_path
    else
      @categories = Category.all
      render 'index'
    end
  end


  def update
    if @category.update(category_params)
      redirect_to categories_path
    else
      render 'edit'
    end
  end

  def destroy
    @category.destroy
    redirect_to categories_path
  end


  private

    def set_category
      @category = Category.find(params[:id])
    end

    def category_params
      params.require(:category).permit(:name)
    end
end