只要用户更改下拉菜单中的值并点击“开始”按钮,我的应用程序中的下拉菜单(由 select_tag 构建)应该调用过滤器类别操作。
现在,我想摆脱“开始”按钮并让观察者(observe_field?)在用户更改下拉菜单中的值后立即调用过滤器类别操作。
下面你会看到我写的代码。它可以使用“Go”按钮工作,但不能仅通过更改下拉菜单中的值来工作。我的 observe_category_select-helper 有什么问题?
带有下拉菜单和项目列表的视图部分
<!-- drop down menu -->
<% form_tag(filter_category_path(:id), :method => :post, :class => 'categories') do %>
<label>Categories</label>
<%= select_tag(:category, options_for_select(Category.all.map {|category| [category.name, category.id]}, @category_id)) %>
<!-- i would like to get rid of this button -->
<%= submit_tag "Go" %>
<% end %>
<!-- list of projects related to categories chosen in drop down menu -->
<ul class="projects">
<% @projects.each do |_project| %>
<li>
<%= link_to(_project.name, _project) %>
</li>
<% end %>
</ul>
<%= observe_category_select -%>
辅助方法
def observe_category_select
observe_field(
:category,
:url => filter_category_path(:id),
:with => 'category',
:on => 'change'
)
end
HelperMethod 的 Javascript 输出
<script type="text/javascript">
//<![CDATA[
new Form.Element.EventObserver('category', function(element, value) {
new Ajax.Request('/categories/id/filter', {asynchronous:true, evalScripts:true, parameters:'category=' + encodeURIComponent(value) + '&authenticity_token=' + encodeURIComponent('edc8b20b701f72285068290779f7ed17cfc1cf8c')})
}, 'change')
//]]>
</script>
类别控制器
class CategoriesController < ApplicationController
def show
@category = Category.find(params[:id])
@category_id = @category.id
@projects = @category.projects.find(:all)
respond_to do |format|
format.html # index.html.erb
end
end
def index
@projects = Category.find(params[:id]).projects.find(:all)
respond_to do |format|
format.html # index.html.erb
end
end
def filter
@category = Category.find(params[:category])
@category_id = @category.id
@projects = @category.projects.find(:all)
respond_to do |format|
format.html # index.html.erb
end
end
结尾
'rake routes | 的输出 grep 过滤器'
filter_category POST /categories/:id/filter {:controller=>"categories", :action=>"filter"}
formatted_filter_category POST /categories/:id/filter.:format {:controller=>"categories", :action=>"filter"}