：選定的值正在頁面提交中重置

Question

從下拉列表中選擇的值將在頁面提交中重置。這是代碼正在使用

<%=select_tag 'num_id', options_for_select(@numbers.collect{ |t| [t.firstno]}),:prompt => "Select"%>

我們如何在ruby on rails的select_tag內設置選定的值。

Answer 1

您可以將另一個參數傳遞給options_for_select來設置選定的選項

<%= select_tag 'num_id', options_for_select(@numbers.map(&:firstno), params[:num_id]), prompt: 'Select' %>

Answer 2

select_tag所選值-

options_for_select(@options, @selected_val)

例：

 options_for_select(1..8, 5)  # creates options from range 1..8, with 5 as selected by default.