Rails：在下拉列表中列出记录

Question

I've got some Users in my DB with a column called "role". The role contains either admin, manager or user as the value. Now I want to loop through this column and list only the respective role once and not all in a Dropdown. The current dropdown lists something like:

• admin
• user
• user
• user
• user
• manager

But I want it to be only like

• admin
• user
• manager

This is my current code:

    <%= f.label :role %>
    <%= f.collection_select(:role, User.all, :role, :role, {prompt:true},    {class: 'form-control'}) %>

Any Ideas? Thank you guys!

Answer 1

要做到这一点， pluck了User通过uniq的角色模型：

<%= f.select(:role, User.pluck(:role).uniq, {prompt:true}, {class: 'form-control'}) %>