我正在编写我的第一个Rails应用程序，但无法解决这个恼人的错误。
我想做什么：该应用已连接到用户的保管箱帐户。用户可以指定应用程序随后查找音频文件的路径。然后将这些音频文件下载，元数据，路径等保存到数据库中的Song模型中，该模型属于相应的用户。
我实现了一个方法，该方法会对Dropbox文件夹编制索引，并在几周前保存文件名和直接链接。现在我添加了一行，将整个Dropbox路径保存到数据库中，突然间什么都不再保存了。
这就是我的歌曲模型：
require "dropbox_helper"
require "open-uri"
class Song < ActiveRecord::Base
belongs_to :user
attr_accessible :artist, :expiration, :is_cached, :length, :dropbox_link, :local_path, :title, :dropbox_path
validates_presence_of :title, :is_cached, :dropbox_link, :dropbox_path
#validates :dropbox_path, :uniqueness => true
def self.fetch_basic_songdata(user)
logger.info "++++DEBUG: Song#fetch_basic_songdata started"
dbh = DropboxHelper.new(user.dropbox_access_key, user.dropbox_access_secret, user.dropbox_folder)
logger.info "++++DEBUG: DropboxHelper initialized"
songs_metadata = dbh.generate_audio_index
logger.info "++++DEBUG: Metadata generated"
#logger.debug songs_metadata.inspect
songs_metadata.each do |smd|
logger.info "Preparing song #{smd['path']} for saving"
songdata = dbh.song_data(smd)
user.songs.create do |s|
s.title = songdata['filename']
s.dropbox_path = songdata['path']
s.dropbox_link = songdata['link']
s.is_cached = false
logger.info "Song #{s[:title]} generated"
logger.info "Song #{s[:title]} saved to the data base"
end
end
end
end
现在，当我在rails控制台中调用Song.fetch_basic_songdata(User.find(1))时，会打印以下内容：
irb(main):002:0> Song.fetch_basic_songdata(User.find(1))
User Load (59.4ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 1]]
Song#fetch_basic_songdata started
Preparing song /audiomixer/01 - Paradise.mp3 for saving
(0.1ms) begin transaction
Song 01 - Paradise.mp3 generated
Song 01 - Paradise.mp3 saved to the data base
(0.1ms) commit transaction
Preparing song /audiomixer/02 - Weirdo.mp3 for saving
(0.1ms) begin transaction
Song 02 - Weirdo.mp3 generated
Song 02 - Weirdo.mp3 saved to the data base
(0.2ms) commit transaction
Preparing song /audiomixer/03 - As It Is When It Was.mp3 for saving
(0.1ms) begin transaction
Song 03 - As It Is When It Was.mp3 generated
Song 03 - As It Is When It Was.mp3 saved to the data base
(0.1ms) commit transaction
Preparing song /audiomixer/04 - Broken Promise.mp3 for saving
(0.2ms) begin transaction
Song 04 - Broken Promise.mp3 generated
Song 04 - Broken Promise.mp3 saved to the data base
(0.1ms) commit transaction
Preparing song /audiomixer/05 - Way Of Life.mp3 for saving
(0.1ms) begin transaction
Song 05 - Way Of Life.mp3 generated
Song 05 - Way Of Life.mp3 saved to the data base
(0.1ms) commit transaction
Preparing song /audiomixer/06 - Bizarre Love Triangle.mp3 for saving
(0.1ms) begin transaction
Song 06 - Bizarre Love Triangle.mp3 generated
Song 06 - Bizarre Love Triangle.mp3 saved to the data base
(0.1ms) commit transaction
Preparing song /audiomixer/07 - All Day Long.mp3 for saving
(0.1ms) begin transaction
Song 07 - All Day Long.mp3 generated
Song 07 - All Day Long.mp3 saved to the data base
(0.1ms) commit transaction
Preparing song /audiomixer/08 - Angel Dust.mp3 for saving
(0.1ms) begin transaction
Song 08 - Angel Dust.mp3 generated
Song 08 - Angel Dust.mp3 saved to the data base
(0.1ms) commit transaction
Preparing song /audiomixer/09 - Every Little Counts.mp3 for saving
(0.1ms) begin transaction
Song 09 - Every Little Counts.mp3 generated
Song 09 - Every Little Counts.mp3 saved to the data base
(0.1ms) commit transaction
Preparing song /audiomixer/10 - State Of The Nation.mp3 for saving
(0.1ms) begin transaction
Song 10 - State Of The Nation.mp3 generated
Song 10 - State Of The Nation.mp3 saved to the data base
(0.0ms) commit transaction
=> [#<Dropbox::API::File bytes=3710598 client_mtime="Fri, 23 Jul 2010 00:09:30 +0000" icon="page_white_sound" is_dir=false mime_type="audio/mpeg" modified="Mon, 22 Apr 2013 12:27:54 +0000" path="/audiomixer/01 - Paradise.mp3" rev="4b6ad8fc0010df0f" revision=1265293564 root="dropbox" size="3.5 MB" thumb_exists=false>, #<Dropbox::API::File bytes=3731496 client_mtime="Fri, 23 Jul 2010 00:09:30 +0000" icon="page_white_sound" is_dir=false mime_type="audio/mpeg" modified="Mon, 22 Apr 2013 12:27:54 +0000" path="/audiomixer/02 - Weirdo.mp3" rev="4b6ad8fd0010df0f" revision=1265293565 root="dropbox" size="3.6 MB" thumb_exists=false>, #<Dropbox::API::File bytes=3620319 client_mtime="Sun, 10 Jan 2010 19:50:28 +0000" icon="page_white_sound" is_dir=false mime_type="audio/mpeg" modified="Mon, 22 Apr 2013 12:27:54 +0000" path="/audiomixer/03 - As It Is When It Was.mp3" rev="4b6ad8fa0010df0f" revision=1265293562 root="dropbox" size="3.5 MB" thumb_exists=false>, #<Dropbox::API::File bytes=3645815 client_mtime="Sun, 10 Jan 2010 19:50:28 +0000" icon="page_white_sound" is_dir=false mime_type="audio/mpeg" modified="Mon, 22 Apr 2013 12:27:54 +0000" path="/audiomixer/04 - Broken Promise.mp3" rev="4b6ad8fb0010df0f" revision=1265293563 root="dropbox" size="3.5 MB" thumb_exists=false>, #<Dropbox::API::File bytes=3954295 client_mtime="Sat, 20 Apr 2013 07:09:30 +0000" icon="page_white_sound" is_dir=false mime_type="audio/mpeg" modified="Mon, 22 Apr 2013 12:27:54 +0000" path="/audiomixer/05 - Way Of Life.mp3" rev="4b6ad8fe0010df0f" revision=1265293566 root="dropbox" size="3.8 MB" thumb_exists=false>, #<Dropbox::API::File bytes=4199193 client_mtime="Sun, 10 Jan 2010 19:50:28 +0000" icon="page_white_sound" is_dir=false mime_type="audio/mpeg" modified="Mon, 22 Apr 2013 12:27:54 +0000" path="/audiomixer/06 - Bizarre Love Triangle.mp3" rev="4b6ad8ff0010df0f" revision=1265293567 root="dropbox" size="4 MB" thumb_exists=false>, #<Dropbox::API::File bytes=5002092 client_mtime="Sun, 10 Jan 2010 19:50:28 +0000" icon="page_white_sound" is_dir=false mime_type="audio/mpeg" modified="Mon, 22 Apr 2013 12:27:54 +0000" path="/audiomixer/07 - All Day Long.mp3" rev="4b6ad9010010df0f" revision=1265293569 root="dropbox" size="4.8 MB" thumb_exists=false>, #<Dropbox::API::File bytes=3595686 client_mtime="Sat, 20 Apr 2013 07:09:31 +0000" icon="page_white_sound" is_dir=false mime_type="audio/mpeg" modified="Mon, 22 Apr 2013 12:27:54 +0000" path="/audiomixer/08 - Angel Dust.mp3" rev="4b6ad8f90010df0f" revision=1265293561 root="dropbox" size="3.4 MB" thumb_exists=false>, #<Dropbox::API::File bytes=4307888 client_mtime="Sat, 20 Apr 2013 07:09:32 +0000" icon="page_white_sound" is_dir=false mime_type="audio/mpeg" modified="Mon, 22 Apr 2013 12:27:54 +0000" path="/audiomixer/09 - Every Little Counts.mp3" rev="4b6ad9000010df0f" revision=1265293568 root="dropbox" size="4.1 MB" thumb_exists=false>, #<Dropbox::API::File bytes=6313648 client_mtime="Sun, 10 Jan 2010 19:50:28 +0000" icon="page_white_sound" is_dir=false mime_type="audio/mpeg" modified="Mon, 22 Apr 2013 12:27:54 +0000" path="/audiomixer/10 - State Of The Nation.mp3" rev="4b6ad9020010df0f" revision=1265293570 root="dropbox" size="6 MB" thumb_exists=false>]
检查是否保存了任何内容：
irb(main):003:0> Song.all
Song Load (0.3ms) SELECT "songs".* FROM "songs"
=> []
我还注意到以logger.info "++++DEBUG:[...]"开头的行根本没有打印。在我插入之前，下面的logger.info行没有打印出来。我真的没有这种行为，你们中的任何人都可以帮忙吗？
PS：我希望提供的信息足够。由于应用程序的行为对我来说完全是随机的，因此我很难理解对问题至关重要的是什么。
编辑：感谢您的评论！按照建议，我尝试使用create!。这是它告诉我的：
irb(main):002:0> Song.fetch_basic_songdata(User.find(1))
User Load (0.1ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 1]]
++++DEBUG: Song#fetch_basic_songdata started
++++DEBUG: DropboxHelper initialized
++++DEBUG: Metadata generated
Preparing song /audiomixer/01 - Paradise.mp3 for saving
(0.1ms) begin transaction
Song 01 - Paradise.mp3 generated
Song 01 - Paradise.mp3 saved to the data base
(0.2ms) rollback transaction
ActiveRecord::RecordInvalid: Validation failed: Is cached can't be blank
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/validations.rb:56:in `save!'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/attribute_methods/dirty.rb:33:in `save!'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/transactions.rb:264:in `block in save!'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/transactions.rb:313:in `block in with_transaction_returning_status'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/database_statements.rb:192:in `transaction'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/transactions.rb:208:in `transaction'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/transactions.rb:311:in `with_transaction_returning_status'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/transactions.rb:264:in `save!'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/associations/has_many_association.rb:14:in `insert_record'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/associations/collection_association.rb:436:in `block (2 levels) in create_record'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/associations/collection_association.rb:344:in `add_to_target'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/associations/collection_association.rb:434:in `block in create_record'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/associations/collection_association.rb:149:in `block in transaction'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/database_statements.rb:192:in `transaction'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/transactions.rb:208:in `transaction'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/associations/collection_association.rb:148:in `transaction'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/associations/collection_association.rb:433:in `create_record'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/associations/collection_association.rb:123:in `create!'
from /var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/associations/collection_proxy.rb:46:in `create!'
from /home/sloth/audiomixer/app/models/song.rb:21:in `block in fetch_basic_songdata'
from /home/sloth/audiomixer/app/models/song.rb:18:in `each'
from /home/sloth/audiomixer/app/models/song.rb:18:in `fetch_basic_songdata'
from (irb):2
from /var/lib/gems/1.9.1/gems/railties-3.2.13/lib/rails/commands/console.rb:47:in `start'
from /var/lib/gems/1.9.1/gems/railties-3.2.13/lib/rails/commands/console.rb:8:in `start'
from /var/lib/gems/1.9.1/gems/railties-3.2.13/lib/rails/commands.rb:41:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `
因此，如果我正确解释了这个问题，问题是is_cached变量似乎是空白的（空？无？）。我认为这是由于在s.is_cached = false分配之前发生错误。任何想法如何找到它？
此外，我刚评论了一些logger.info行并添加了新行。重新启动服务器后，我再次尝试打印了我评论的行，但没有新的。我是否缺少使用旧文件的Rails的一些非常重要的信息？在过去的几周里，我一直在做同样的事情，从未经历过任何这种奇怪的经历。
答案 0 :(得分：3)
您不应将validates_presence_of与布尔属性一起使用，因为它通过调用blank?方法检查该属性是否存在。但是，false.blank?为真，因此当属性为false时，它永远不会让您保存记录。
您可能还需要注意，rails控制台不会自动选择您对代码所做的更改。您需要调用reload!或重新启动控制台。使用reload!时，请注意在重新加载调用之前没有创建对象实例！闲逛 - 他们可能指的是上一版的课程。