如何使form_for选择帮助程序显示日期降序排列？

I'm new to both Ruby and Rails and am having trouble getting a select drop down to show the current year first and then go back 30 years in descending order. I'm using form_for to generate the form/fields.

我是Ruby和Rails的新手，我很难通过选择下拉来显示当前年份，然后按降序返回30年。我正在使用form_for来生成表单/字段。

I can get it to work in ascending order with the following:

我可以通过以下方式按升序工作：

<%= builder.label :modelyear, "Model Year" %>        
<%= builder.select :modelyear, (Time.zone.now.year - 30)..(Time.zone.now.year + 0) %>

These do not work:

这些不起作用：

<%= builder.label :modelyear, "Model Year" %>        
<%= builder.select :modelyear, (Time.zone.now.year)..(Time.zone.now.year - 30) %>

<%= builder.label :modelyear, "Model Year" %>        
<%= builder.select :modelyear, (Time.zone.now.year + 0)..(Time.zone.now.year - 30) %>

Edit: complete code as requested (with original attempt at selector)

编辑：按要求完成代码（原始尝试选择器）

<%= form_for(@user) do |f| %>
        <%= render 'shared/error_messages' %>

    <%= f.label :first_name %>
    <%= f.text_field :first_name %>
    <br /><br />

    <%= f.label :last_name %>
    <%= f.text_field :last_name %>
    <br /><br />

    <%= f.label :email %>
    <%= f.text_field :email %>
    <br /><br />

    <%= f.label :address1 %>
    <%= f.text_field :address1 %>
    <br /><br />

    <%= f.label :address2 %>
    <%= f.text_field :address2 %>
    <br /><br />

    <%= f.label :city %>
    <%= f.text_field :city %>
    <br /><br />

    <%= f.label :state %>
    <%= f.text_field :state %>
    <br /><br />

    <%= f.label :zipcode %>
    <%= f.text_field :zipcode %>
    <br /><br />

    <%= f.label :country %>
    <%= f.text_field :country %>
    <br /><br />

    <!-- Fields For Product -->
    <%= f.fields_for :products do |builder| %>
    <div>
             <%= builder.label :serial, "Serial Number" %>        
             <%= builder.text_field :serial %>
             <br /><br />


             <%= builder.label :modelyear, "Model Year" %>        
             <%= builder.select :modelyear, (Time.zone.now.year - 30)..(Time.zone.now.year + 0) %>
             <br /><br />

 </div>
<% end %>

<%= f.submit "Register Your Product", class: "button" %>

user.rb

user.rb

    class User < ActiveRecord::Base
has_many :products, dependent: :destroy
accepts_nested_attributes_for :products, :allow_destroy => true
before_save { email.downcase! }
validates :first_name, presence: true
validates :last_name, presence: true
validates :email, presence: true
validates :address1, presence: true
validates :address2, length: { maximum: 30 }
validates :city, presence: true
validates :state, length: { maximum: 20 }
validates :zipcode, length: { maximum: 20 }
validates :country, presence: true
    end

product.rb

product.rb

    class Product < ActiveRecord::Base
belongs_to :user
validates :serial, presence: true
validates :modelyear,     length: { maximum: 4 }
    end

2 个解决方案

#1

This should work

这应该工作

<%= builder.select :modelyear, ((Time.zone.now.year - 30)..(Time.zone.now.year + 0)).to_a.reverse %>

Here I am converting the Range object to an Array, which is also accepted by select as parameter. So you can use the convenient array reverse method.

这里我将Range对象转换为Array，select也作为参数接受。所以你可以使用方便的数组反向方法。

#2

Try this:

尝试这个：

<%= builder.select :modelyear, Time.zone.now.year.downto(Time.zone.now.year - 30)
.to_a, class:'form-control' %>

#1