[Function Category] Ruby on Rails Blog with categroy 分類功能

category的重點就在選單，配上simple_form會讓事情簡單很多。
<%=f.select :category_id,Category.all.map{|c| [c.name, c.id]}%>

ch01_post
rails g scaffold post title content:text

ch02_category
rails g scaffold category name
可以選擇的表單
參考資料
https://www.jianshu.com/p/02168102eb97

<%= simple_form_for @post do |f|%>

<%=f.input :title%>

<%=f.input :content%>

- <%=f.select :category_id,Category.all.map{|c| [c.id]}%>

+<%=f.select :category_id,Category.all.map{|c| [c.name, c.id]}%>

<%=f.submit %>

<%end%>

hello
->將|c| [c.id]換成|c| [c.name,c.id]