我在部署到Heroku的其中一个应用程序时遇到了一些问题。本地应用程序工作正常，但是当我按下违反Ajax请求的按钮时，在Heroku上我得到500错误。错误更具体地来自我的控制器中称为添加的方法。以下是Heroku的日志。链接到应用： https://ouinyc.herokuapp.com/
** p.s要查看提示您必须注册的错误的按钮，它是停止和播放按钮下方的两个按钮。 **
奇怪的是，这是最突出的错误。
NoMethodError (undefined method `delete!' for nil:NilClass):
app/controllers/static_pages_controller.rb:27:in `add_song'
以下是Heroku的一些日志
2016-04-25T22:28:09.603876+00:00 app[web.1]: vendor/bundle/ruby/2.2.0/gems/rack-1.6.4/lib/rack/lock.rb:17:in `call'
2016-04-25T22:28:09.603878+00:00 app[web.1]: vendor/ruby-2.2.4/lib/ruby/2.2.0/webrick/httpserver.rb:138:in `service'
2016-04-25T22:28:09.603874+00:00 app[web.1]: vendor/bundle/ruby/2.2.0/gems/rack-1.6.4/lib/rack/sendfile.rb:113:in `call'
2016-04-25T22:28:09.603875+00:00 app[web.1]: vendor/bundle/ruby/2.2.0/gems/railties-4.2.5/lib/rails/engine.rb:518:in `call'
2016-04-25T22:28:09.603879+00:00 app[web.1]: vendor/ruby-2.2.4/lib/ruby/2.2.0/webrick/httpserver.rb:94:in `run'
2016-04-25T22:28:09.603877+00:00 app[web.1]: vendor/bundle/ruby/2.2.0/gems/rack-1.6.4/lib/rack/content_length.rb:15:in `call'
2016-04-25T22:28:09.603878+00:00 app[web.1]: vendor/bundle/ruby/2.2.0/gems/rack-1.6.4/lib/rack/handler/webrick.rb:88:in `service'
2016-04-25T22:28:09.603880+00:00 app[web.1]: vendor/ruby-2.2.4/lib/ruby/2.2.0/webrick/server.rb:294:in `block in start_thread'
2016-04-25T22:28:09.603881+00:00 app[web.1]:
2016-04-25T22:28:09.603881+00:00 app[web.1]:
2016-04-25T22:28:11.095771+00:00 app[web.1]: Rendered layouts/_shim.html.erb (0.4ms)
2016-04-25T22:28:11.133322+00:00 app[web.1]: Rendered layouts/_audio_part.html.erb (7.2ms)
2016-04-25T22:28:11.133624+00:00 app[web.1]: Completed 200 OK in 50ms (Views: 45.6ms | ActiveRecord: 3.8ms)
2016-04-25T22:28:11.107578+00:00 app[web.1]: Rendered layouts/_header.html.erb (7.9ms)
2016-04-25T22:28:11.105471+00:00 app[web.1]: User Load (3.8ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 ORDER BY "users"."id" ASC LIMIT 1 [["id", 1]]
2016-04-25T22:28:11.120143+00:00 app[web.1]: Rendered layouts/_footer.html.erb (2.8ms)
2016-04-25T22:28:11.090234+00:00 app[web.1]: Rendered static_pages/home.html.erb within layouts/application (0.6ms)
2016-04-25T22:28:11.081117+00:00 app[web.1]: Started GET "/home" for 98.14.169.85 at 2016-04-25 22:28:11 +0000
2016-04-25T22:28:11.083194+00:00 app[web.1]: Processing by StaticPagesController#home as HTML
2016-04-25T22:28:11.135758+00:00 heroku[router]: at=info method=GET path="/home" host=ouinyc.herokuapp.com request_id=2be011c5-bff4-4ac6-8c0b-a681f7826f32 fwd="98.14.169.85" dyno=web.1 connect=0ms service=63ms status=200 bytes=7100
2016-04-25T22:28:23.338889+00:00 heroku[router]: at=info method=GET path="/90210%20by%20Travis%20Scott.mp3" host=ouinyc.herokuapp.com request_id=b8770d58-15e2-40d9-a002-8ddd4fb9d4db fwd="98.14.169.85" dyno=web.1 connect=0ms service=166ms status=206 bytes=8526220
2016-04-25T22:28:41.387156+00:00 heroku[router]: at=info method=POST path="/adding" host=ouinyc.herokuapp.com request_id=5c6bd67b-2c43-4086-90ff-b0fd0f524cd9 fwd="98.14.169.85" dyno=web.1 connect=0ms service=58ms status=500 bytes=1754
2016-04-25T22:28:41.375423+00:00 app[web.1]: Started POST "/adding" for 98.14.169.85 at 2016-04-25 22:28:41 +0000
2016-04-25T22:28:41.377153+00:00 app[web.1]: Processing by StaticPagesController#add_song as */*
2016-04-25T22:28:41.377249+00:00 app[web.1]: Parameters: {"data_value"=>"\"https://ouinyc.herokuapp.com/90210%20by%20Travis%20Scott.mp3\"", "authenticity_token"=>""}
2016-04-25T22:28:41.379928+00:00 app[web.1]: User Load (0.5ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 ORDER BY "users"."id" ASC LIMIT 1 [["id", 1]]
2016-04-25T22:28:41.381122+00:00 app[web.1]: User Load (0.5ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIMIT 1 [["id", 1]]
2016-04-25T22:28:41.382269+00:00 app[web.1]: Completed 500 Internal Server Error in 5ms (ActiveRecord: 1.0ms)
2016-04-25T22:28:41.385136+00:00 app[web.1]:
2016-04-25T22:28:41.385145+00:00 app[web.1]: NoMethodError (undefined method `delete!' for nil:NilClass):
2016-04-25T22:28:41.385146+00:00 app[web.1]: app/controllers/static_pages_controller.rb:27:in `add_song'
2016-04-25T22:28:41.385147+00:00 app[web.1]:
修改 所以这个问题看起来必须要处理控制器。这就是说我不明白为什么它说字符串对象是空的。
控制器
class StaticPagesController < ApplicationController
respond_to :js, :json, :html
def get_songs()
if user_signed_in?
session[:user_id] = current_user.id
present_user = User.find(session[:user_id])
present_user = present_user.playlist.keys
@songs = present_user
respond_to do |format|
format.json { render :json => @songs}
end
end
end
def add_song()
if user_signed_in?
session[:user_id] = current_user.id
present_user = User.find(session[:user_id])
var = params[:data_value]
var = var.sub!("http://localhost:3000/", "")
var.delete!('""','')
present_user.playlist.store(var, 1)
if present_user.save
render json: {success: "It works"}
end
end
end
def remove_song()
if user_signed_in?
session[:user_id] = current_user.id
present_user = User.find(session[:user_id])
var = params[:data_value]
present_user.playlist.delete(var)
if present_user.save
render json: {success: "It works"}
end
end
end
def news
end
def home
end
end
ajax请求
$.ajax({
url: "removing",
type: "post",
data: {data_value: JSON.stringify(player.src), authenticity_token: "<%= @form_auth_token %>" }
}
);
答案 0 :(得分：1)
嗯，问题代码如下，请不要＆＃39;没有真正原因使用!的非纯方法。此行评估var至nil，因为之前的var值没有前缀行：
var = var.sub!("http://localhost:3000/", "")
所以下一个var.delete!会导致异常：
代码的一部分：
var = params[:data_value]
var = var.sub!("http://localhost:3000/", "")
var.delete!('""','')
present_user.playlist.store(var, 1)
可以替换为（因为您传递的是JSON编码值）：
song = JSON.parse((params[:data_value]).sub("localhost:3000/", ""),
{:quirks_mode => true})'
present_user.playlist.store(song, 1)