我浏览了Michael Hartl的Rails教程书，我想使用Ajax进行自动提要刷新，创建微博和删除微博。
据我了解，我只需要在正确的partial内部的表单中指定remote：true参数，并在适当的方法内响应js。
然而，当我尝试使用create动作完成部分刷新时，我得到一个奇怪的NoMethodError，表明我的@feed_items是一个nil对象。
Started POST "/microposts" for 77.70.8.167 at 2016-06-28 10:21:32 +0000
Processing by MicropostsController#create as JS
Parameters: {"utf8"=>"✓", "authenticity_token"=>"qJHp9flp+EV+cxdeF69L8eSzC1fMsjr+mi57f3u3z2Y/fJI9dl1to9t4jlrX4g2uhIP67FiwvjwL7SP2Hmc4fw==", "micropost"=>{"content"=>"dsdsds"}, "commit"=>"Post"}
User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 1]]
(0.1ms) begin transaction
SQL (0.3ms) INSERT INTO "microposts" ("content", "user_id", "created_at", "updated_at") VALUES (?, ?, ?, ?) [["content", "dsdsds"], ["user_id", 1], ["created_at", "2016-06-28 10:21:32.797365"], ["updated_at", "2016-06-28 10:21:32.797365"]]
(11.1ms) commit transaction
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@NilClass
Rendered shared/_feed.html.erb (7.7ms)
Rendered microposts/create.js.erb (11.5ms)
Completed 500 Internal Server Error in 43ms (ActiveRecord: 11.7ms)
NoMethodError (undefined method `any?' for nil:NilClass):
app/views/shared/_feed.html.erb:3:in `_app_views_shared__feed_html_erb___1168566426182367941_69986820092480'
app/views/microposts/create.js.erb:1:in `_app_views_microposts_create_js_erb__3336806296105309297_69986601152860'
app/controllers/microposts_controller.rb:9:in `create'
这是我的_micropost.html.erb部分：
<%= form_for(@micropost, remote: true) do |f| %>
<%= render 'shared/error_messages', object: f.object %>
<div class="field">
<%= f.text_area :content, placeholder: "Compose new micropost..." %>
</div>
<%= f.submit "Post", class: "btn btn-primary" %>
<span class="picture">
<%= f.file_field :picture, accept: 'image/jpeg, image/gif, image/png' %>
</span>
<% end %>
<script type="text/javascript">
$('#micropost_picture').bind('change', function(){
size_in_megabytes = this.files[0].size/1024/1024;
if (size_in_megabytes > 5) {
alert('Maximum file size is 5MB. Please chose a smaller file.')
}
})
</script>
Create.js.erb：
$(".ajaxreloadposts").html("<%= escape_javascript(render('shared/feed')) %>");
_feed.html.erb：
<% if @feed_items.any? %>
<ol class="microposts">
<%= render @feed_items %>
</ol>
<%= will_paginate @feed_items %>
<% end %>
创建行动：
def create
@micropost = current_user.microposts.build(micropost_params)
if @micropost.save!
# flash[:success] = "Micropost created!"
respond_to do |format|
format.html { redirect_to root_path }
format.js
end
else
@feed_items = []
render 'static_pages/home'
end
end
_home_logged_in.html.erb：
<div class="row">
<aside class="col-md-4">
<section class="user_info">
<%= render 'shared/user_info' %>
</section>
<section class="stats">
<%= render 'shared/stats' %>
</section>
<section class="micropost_form">
<%= render 'shared/micropost_form' %>
</section>
</aside>
<div class="col-md-8">
<h3>Where are your buddies right now?</h3>
<%= render 'shared/gmaps' %>
</div>
<div class="col-md-8">
<h3>Micropost Feed</h3>
<span class="ajaxreloadposts">
<%= render 'shared/feed' %>
</span>
</div>
</div>
最后，我想，我的static_pages_controller的相关部分：
def home
if logged_in?
@micropost = current_user.microposts.build
@feed_items = current_user.feed.paginate(page: params[:page])
@gmaps_users = current_user.gmaps_feed
@hash = Gmaps4rails.build_markers(@gmaps_users) do |spot, marker|
marker.lat spot.lat
marker.lng spot.lng
marker.infowindow spot.user.name
end
if !current_user.checkin.nil?
@user_lat = current_user.checkin.lat
@user_lng = current_user.checkin.lng
end
end
end
我尝试了这些资源，但徒劳无功： AJAX to update micropost vote up/down partial only refreshes the most recent post 和 AJAX feed update on post 和 How to update feed using ajax in Rails 4.0
我可能错过了一些东西，但由于我是Rails的新手，我希望你会怜悯。
感谢您的时间，帮助和欢呼。
答案 0 :(得分：0)
好吧，它可能有点像noobish，但我设法通过在create和destroy方法中插入一个名为@feed_items的实例变量来解决问题。
def create
@feed_items = current_user.feed.paginate(page: params[:page])
@micropost = current_user.microposts.build(micropost_params)
if @micropost.save!
# flash[:success] = "Micropost created!"
respond_to do |format|
format.html { redirect_to root_path }
format.js
end
else
@feed_items = []
render 'static_pages/home'
end
end
def destroy
@micropost.destroy
@feed_items = current_user.feed.paginate(page: params[:page])
# flash[:success] = "Micropost deleted!"
respond_to do |format|
format.html { redirect_to request.referrer || root_url }
format.js
end
end
这里是微博创建和删除的轨道输出：
Started POST "/microposts" for 77.70.8.167 at 2016-06-28 12:20:56 +0000
Processing by MicropostsController#create as JS
Parameters: {"utf8"=>"✓", "authenticity_token"=>"wd7XeH4MYDINH2+PrDy8perRJ77VKTwjZ82tsHdESbNWM6yw8Tj11KgU9otscfr6iuHWBUEruOH2DvU5EpS+qg==", "micropost"=>{"content"=>"workworkwork"}, "commit"=>"Post"}
User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 1]]
(0.1ms) begin transaction
SQL (0.3ms) INSERT INTO "microposts" ("content", "user_id", "created_at", "updated_at") VALUES (?, ?, ?, ?) [["content", "workworkwork"], ["user_id", 1], ["created_at", "2016-06-28 12:20:56.699428"], ["updated_at", "2016-06-28 12:20:56.699428"]]
(11.0ms) commit transaction
(3.5ms) SELECT COUNT(*) FROM "microposts" WHERE (user_id IN (SELECT followed_id FROM relationships
WHERE follower_id = 1)
OR user_id = 1)
Micropost Load (1.2ms) SELECT "microposts".* FROM "microposts" WHERE (user_id IN (SELECT followed_id FROM relationships
WHERE follower_id = 1)
OR user_id = 1) ORDER BY "microposts"."created_at" DESC LIMIT 30 OFFSET 0
CACHE...
Rendered microposts/_micropost.html.erb (43.1ms)
Rendered shared/_feed.html.erb (60.3ms)
Rendered microposts/create.js.erb (65.5ms)
Completed 200 OK in 99ms (Views: 76.4ms | ActiveRecord: 17.6ms)
Started DELETE "/microposts/348" for 77.70.8.167 at 2016-06-28 12:20:59 +0000
Processing by MicropostsController#destroy as JS
Parameters: {"id"=>"348"}
User Load (0.3ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 1]]
Micropost Load (0.1ms) SELECT "microposts".* FROM "microposts" WHERE "microposts"."user_id" = ? AND "microposts"."id" = ? ORDER BY "microposts"."created_at" DESC LIMIT 1 [["user_id", 1], ["id", 348]]
(0.1ms) begin transaction
SQL (0.4ms) DELETE FROM "microposts" WHERE "microposts"."id" = ? [["id", 348]]
(9.5ms) commit transaction
(0.5ms) SELECT COUNT(*) FROM "microposts" WHERE (user_id IN (SELECT followed_id FROM relationships
WHERE follower_id = 1)
OR user_id = 1)
Micropost Load (1.3ms) SELECT "microposts".* FROM "microposts" WHERE (user_id IN (SELECT followed_id FROM relationships
WHERE follower_id = 1)
OR user_id = 1) ORDER BY "microposts"."created_at" DESC LIMIT 30 OFFSET 0
CACHE...
Rendered microposts/_micropost.html.erb (50.9ms)
Rendered shared/_feed.html.erb (65.8ms)
Rendered microposts/destroy.js.erb (71.0ms)
Completed 200 OK in 99ms (Views: 75.6ms | ActiveRecord: 18.9ms)