socialforge/app/views/welcome/_search_project.html.erb

<%
	select_option = []
	(select_option << ['项目', 'projects']) if project_type == Project::ProjectType_project
	(select_option << ['课程', 'courses']) if project_type == Project::ProjectType_course
	select_option << ['用户', 'users']
%>
<style type="text/css">
form #q, form #search_type{
	-webkit-box-sizing: border-box;
	-moz-box-sizing: border-box;
	box-sizing: border-box;
	display: inline-block;
	margin: 0px;
	padding: 5px;
	height: 33px;
}
form #q{
	font-size: 13px;
	border-top-left-radius: 5px;
	border-bottom-left-radius: 5px;
	border-right: none;

}
form #search_type{
	font-size: 13px;
	color: #363739;
	border-top-right-radius: 5px;
	border-bottom-right-radius: 5px;
	border-bottom-left-radius: 0px;
	border-top-left-radius: 0px;
	border-left: 1px outset #83A9A9;
	margin-left: 0px;
	-webkit-appearance: none;
	-moz-appearance: none;
	text-indent: 0.01px;
	text-overflow: '';
}

form #search_by
{
    font-size: 13px;
    color: #363739;
    border-top-right-radius: 5px;
    border-bottom-right-radius: 5px;
    border-bottom-left-radius: 0px;
    border-top-left-radius: 0px;
    border-left: 1px outset #83A9A9;
    margin-left: 0px;
    -webkit-appearance: none;
    -moz-appearance: none;
    text-indent: 0.01px;
    text-overflow: '';
    -moz-box-sizing: border-box;
    box-sizing: border-box;
    display: inline-block;
    padding: 5px;
    height: 33px;
    display: none;
}

.search_widget{
	display:inline-block;
	border-radius: 5px;
}
.search_widget:hover{
	box-shadow: 0px 0px 3px #56B4EF;
}
<%#完了把上面东西放到 .css 里%>
</style>
<script type="text/javascript">
  function searchTypeChange()
  {
      if($("#search_type").val() == "users")
      {
          $("#search_by").show();
      }
      else
      {
          $("#search_by").hide();
      }
  }

  function searchByChange()
  {
      $("#search_by_input").val($("#search_by").val());
  }
</script>
<%= form_tag({controller: :welcome, action: :search }, method: :get) do %>
<div class="project-search" style="float: right; width: 260px">
	<div class='search_widget' >

		<%= text_field_tag :q, nil, placeholder:'请输入要搜索的关键字', style:"float:left" %>
        <input type="text" name="search_by_input" style="display: none" id="search_by_input" value="0">
		<%= select_tag(:search_type, options_for_select(select_option), :onchange => "searchTypeChange();", :style => "float:right" ) %>
        <%= select_tag(:search_by,options_for_select([["昵称","0"],["姓名","1"],["邮箱","2"]]), :onchange => "searchByChange();",:style => "float:right" )  %>
	</div>
		<%#= hidden_field_tag 'project_type', project_type %>
		<%= submit_tag l(:label_search), :class => "enterprise", :name => nil,:style =>"float: right; margin-left:3px;margin-top:2px" %>
		</div>	
<% end %>