【发布时间】：2011-12-01 07:31:45
【问题描述】：
在 Michael Hartl 的 Ruby on Rails Tutorial 第 12 章中，用户的个人资料页面上有一个按钮，您可以翻转以关注或取消关注他/她。 （见图12.12和12.13）
我正在使用 rvm 1.8.6 和 Rails 3.1.1。
当我使用 Prototype 时，单击按钮的行为可以正常工作。 在 /sample_app/app/views/layouts/application.html.erb 中，
<%= javascript_include_tag :defaults %>
点击“关注”时，它会先 POST 然后 GET 以重新呈现页面。日志如下。
Started POST "/relationships" for 127.0.0.1 at 2011-11-30 22:07:04 -0800
Processing by RelationshipsController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"sVoNM/yyDmn0czvbza+dxzLsPW4mPNlGxAI1vKN7Ez4=", "relationship"=>{"followed_id"=>"13"}, "commit"=>"Follow"}
User Load (0.1ms) SELECT "users".* FROM "users" WHERE "users"."id" = 1 LIMIT 1
User Load (0.3ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", "13"]]
SQL (0.6ms) INSERT INTO "relationships" ("created_at", "followed_id", "follower_id", "updated_at") VALUES (?, ?, ?, ?) [["created_at", Thu, 01 Dec 2011 06:07:04 UTC +00:00], ["followed_id", 13], ["follower_id", 1], ["updated_at", Thu, 01 Dec 2011 06:07:04 UTC +00:00]]
Redirected to ht.p://localhost:3000/users/13
Completed 302 Found in 52ms
Started GET "/users/13" for 127.0.0.1 at 2011-11-30 22:07:04 -0800
Processing by UsersController#show as HTML
Parameters: {"id"=>"13"}
User Load (0.1ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", "13"]]
User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = 1 LIMIT 1
Relationship Load (0.2ms) SELECT "relationships".* FROM "relationships" WHERE "relationships"."follower_id" = 1 AND "relationships"."followed_id" = 13 LIMIT 1
CACHE (0.0ms) SELECT "relationships".* FROM "relationships" WHERE "relationships"."follower_id" = 1 AND "relationships"."followed_id" = 13 LIMIT 1
Rendered users/_unfollow.html.erb (6.9ms)
Rendered users/_follow_form.html.erb (54.5ms)
(0.2ms) SELECT COUNT(*) FROM "microposts" WHERE "microposts"."user_id" = 13
CACHE (0.0ms) SELECT COUNT(*) FROM "microposts" WHERE "microposts"."user_id" = 13
(0.2ms) SELECT COUNT(*) FROM "users" INNER JOIN "relationships" ON "users"."id" = "relationships"."followed_id" WHERE "relationships"."follower_id" = 13
(0.1ms) SELECT COUNT(*) FROM "users" INNER JOIN "relationships" ON "users"."id" = "relationships"."follower_id" WHERE "relationships"."followed_id" = 13
Rendered shared/_stats.html.erb (4.2ms)
Rendered users/show.html.erb within layouts/application (67.5ms)
Rendered layouts/_stylesheets.html.erb (1.4ms)
Rendered layouts/_header.html.erb (2.5ms)
Rendered layouts/_footer.html.erb (0.7ms)
Completed 200 OK in 100ms (Views: 83.1ms | ActiveRecord: 1.9ms)
但是，在我按照第 13 章切换到 JQuery 后，单击关注按钮的行为导致异常并导致 Web 服务器崩溃。 在我将 /sample_app/app/views/layouts/application.html.erb 修改为之后，
<%= javascript_include_tag "application" %>
它会 POST 两次。而且我猜 db 唯一违规使 Ruby 崩溃了。日志如下。
Started POST "/relationships" for 127.0.0.1 at 2011-11-30 21:08:51 -0800
Processing by RelationshipsController#create as JS
Parameters: {"utf8"=>"✓", "authenticity_token"=>"sVoNM/yyDmn0czvbza+dxzLsPW4mPNlGxAI1vKN7Ez4=", "relationship"=>{"followed_id"=>"19"}, "commit"=>"Follow"}
User Load (0.1ms) SELECT "users".* FROM "users" WHERE "users"."id" = 1 LIMIT 1
User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", "19"]]
SQL (4.6ms) INSERT INTO "relationships" ("created_at", "followed_id", "follower_id", "updated_at") VALUES (?, ?, ?, ?) [["created_at", Thu, 01 Dec 2011 05:08:51 UTC +00:00], ["followed_id", 19], ["follower_id", 1], ["updated_at", Thu, 01 Dec 2011 05:08:51 UTC +00:00]]
Relationship Load (0.2ms) SELECT "relationships".* FROM "relationships" WHERE "relationships"."follower_id" = 1 AND "relationships"."followed_id" = 19 LIMIT 1
Rendered users/_unfollow.html.erb (3.7ms)
(0.2ms) SELECT COUNT(*) FROM "users" INNER JOIN "relationships" ON "users"."id" = "relationships"."follower_id" WHERE "relationships"."followed_id" = 19
Rendered relationships/create.js.erb (7.7ms)
Completed 200 OK in 103ms (Views: 13.7ms | ActiveRecord: 6.0ms)
Started POST "/relationships" for 127.0.0.1 at 2011-11-30 21:08:51 -0800
Processing by RelationshipsController#create as JS
Parameters: {"utf8"=>"✓", "authenticity_token"=>"sVoNM/yyDmn0czvbza+dxzLsPW4mPNlGxAI1vKN7Ez4=", "relationship"=>{"followed_id"=>"19"}, "commit"=>"Follow"}
User Load (0.1ms) SELECT "users".* FROM "users" WHERE "users"."id" = 1 LIMIT 1
User Load (0.3ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", "19"]]
SQL (0.5ms) INSERT INTO "relationships" ("created_at", "followed_id", "follower_id", "updated_at") VALUES (?, ?, ?, ?) [["created_at", Thu, 01 Dec 2011 05:08:51 UTC +00:00], ["followed_id", 19], ["follower_id", 1], ["updated_at", Thu, 01 Dec 2011 05:08:51 UTC +00:00]]
SQLite3::ConstraintException: constraint failed: INSERT INTO "relationships" ("created_at", "followed_id", "follower_id", "updated_at") VALUES (?, ?, ?, ?)
Completed 500 Internal Server Error in 86ms
SQLite3::ConstraintException (columns follower_id, followed_id are not unique):
Rendered /home/anson/.rvm/gems/ruby-1.9.2-p290/gems/actionpack-3.1.1/lib/action_dispatch/middleware/templates/rescues/_trace.erb (1.2ms)
Rendered /home/anson/.rvm/gems/ruby-1.9.2-p290/gems/actionpack-3.1.1/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (1.0ms)
Rendered /home/anson/.rvm/gems/ruby-1.9.2-p290/gems/actionpack-3.1.1/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (4.2ms)
/home/anson/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.1/lib/active_record/connection_adapters/sqlite_adapter.rb:84: [BUG] Segmentation fault
ruby 1.9.2p290 (2011-07-09 revision 32553) [x86_64-linux]
-- control frame ----------
c:0044 p:---- s:0205 b:0205 l:000204 d:000204 CFUNC :close
...
[NOTE]
You may have encountered a bug in the Ruby interpreter or extension libraries.
Bug reports are welcome.
Aborted
有人可以帮忙吗？
代码如下。 app/views/users/_follow_form.html.erb
<% unless current_user?(@user) %>
<div id="follow_form">
<% if current_user.following?(@user) %>
<%= render 'unfollow' %>
<% else %>
<%= render 'follow' %>
<% end %>
</div>
<% end %>
app/views/users/_follow.html.erb
<%= form_for current_user.relationships.build(:followed_id => @user.id),
:remote => true do |f| %>
<div><%= f.hidden_field :followed_id %></div>
<div class="actions"><%= f.submit "Follow" %></div>
<% end %>
app/views/users/_unfollow.html.erb
<%= form_for current_user.relationships.find_by_followed_id(@user),
:html => { :method => :delete },
:remote => true do |f| %>
<div class="actions"><%= f.submit "Unfollow" %></div>
<% end %>
app/controllers/relationships_controller.rb
class RelationshipsController < ApplicationController
before_filter :authenticate
def create
@user = User.find(params[:relationship][:followed_id])
current_user.follow!(@user)
respond_to do |format|
format.html { redirect_to @user }
format.js
end
end
def destroy
@user = Relationship.find(params[:id]).followed
current_user.unfollow!(@user)
respond_to do |format|
format.html { redirect_to @user }
format.js
end
end
end
app/views/relationships/create.js.erb
$("follow_form").update("<%= escape_javascript(render('users/unfollow')) %>")
$("followers").update('<%= "#{@user.followers.count} followers" %>')
app/views/relationships/destroy.js.erb
$("follow_form").update("<%= escape_javascript(render('users/follow')) %>")
$("followers").update('<%= "#{@user.followers.count} followers" %>')
【问题讨论】：
-
虽然我需要查看代码，但可能是默认表单行为（提交）正在采取行动以及您的 js 代码。尝试在处理表单提交的 js 代码开头添加一个 e.preventDefault。
-
我已经添加了代码。你能告诉我在哪里可以添加 e.preventDefault 吗？
-
在js事件处理函数中，function(e) { e.preventDefault(); ... }
-
如果您使用的是 Rails 3.1，那么您并没有完全遵循使用 Rails 3.0 的教程。使用与教程中不同的 Rails 版本可能会产生不同的结果。我建议使用教程中使用的确切 gem 版本。如果你渴望使用 Rails 3.1，请参阅第 13 章。目前正在准备一个新版本，整个使用 Rails 3.1。
标签： ruby-on-rails railstutorial.org