ActiveRecord 4.1.1正在生成一些特殊的SQL保存postgres窒息：
SELECT "projects".* FROM "projects" WHERE ('uid') LIMIT 1
PG::InvalidTextRepresentation: ERROR: invalid input syntax for type boolean: "uid"
我非常确定＆＃34;布尔＆＃34;这里提到的实际上是WHERE()语法，它期望一个布尔表达式作为参数。
uid被定义为我模型的主键（见下文）......但是为什么它只是在WHERE('uid')执行select_all时（参见stacktrace）？ （为什么在保存时执行select_all？）
p = Project.new(name: "test", description: "test", workflow_id: 1)
=> #<Project name: "test", description: "test", user_id: nil, uid: nil, created_at: nil, updated_at: nil, workflow_id: 1, active: nil>
irb(main):031:0> p.save
(1.9ms) BEGIN
Project Load (5.5ms) SELECT "projects".* FROM "projects" WHERE ('uid') LIMIT 1
PG::InvalidTextRepresentation: ERROR: invalid input syntax for type boolean: "uid"
LINE 1: SELECT "projects".* FROM "projects" WHERE ('uid') LIMIT 1
^
: SELECT "projects".* FROM "projects" WHERE ('uid') LIMIT 1
(1.7ms) ROLLBACK
ActiveRecord::StatementInvalid: PG::InvalidTextRepresentation: ERROR: invalid input syntax for type boolean: "uid"
LINE 1: SELECT "projects".* FROM "projects" WHERE ('uid') LIMIT 1
^
: SELECT "projects".* FROM "projects" WHERE ('uid') LIMIT 1
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/connection_adapters/postgresql_adapter.rb:815:in `async_exec'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/connection_adapters/postgresql_adapter.rb:815:in `block in exec_no_cache'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/connection_adapters/abstract_adapter.rb:373:in `block in log'
from /app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.1/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/connection_adapters/abstract_adapter.rb:367:in `log'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/connection_adapters/postgresql_adapter.rb:815:in `exec_no_cache'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:137:in `exec_query'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/connection_adapters/postgresql_adapter.rb:947:in `select'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/connection_adapters/abstract/database_statements.rb:31:in `select_all'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/connection_adapters/abstract/query_cache.rb:69:in `select_all'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/querying.rb:39:in `find_by_sql'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/relation.rb:603:in `exec_queries'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/relation.rb:487:in `load'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/relation.rb:231:in `to_a'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/relation/finder_methods.rb:451:in `find_take'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/relation/finder_methods.rb:98:in `take'
... 41 levels...
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/connection_adapters/abstract/database_statements.rb:211:in `block in transaction'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/connection_adapters/abstract/database_statements.rb:219:in `within_new_transaction'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/connection_adapters/abstract/database_statements.rb:211:in `transaction'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/transactions.rb:208:in `transaction'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/transactions.rb:326:in `with_transaction_returning_status'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/transactions.rb:268:in `block in save'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/transactions.rb:283:in `rollback_active_record_state!'
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.1/lib/active_record/transactions.rb:267:in `save'
from (irb):31
from /app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.1/lib/rails/commands/console.rb:90:in `start'
from /app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.1/lib/rails/commands/console.rb:9:in `start'
from /app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.1/lib/rails/commands/commands_tasks.rb:69:in `console'
from /app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.1/lib/rails/commands/commands_tasks.rb:40:in `run_command!'
from /app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.1/lib/rails/commands.rb:17:in `<top (required)>'
from /app/bin/rails:4:in `require'
from /app/bin/rails:4:in `<main>
class Project < ActiveRecord::Base
self.primary_key = "uid"
end
module ActiveRecordUIDExtension
extend ActiveSupport::Concern
def generate_uid
return unless self.class.column_names.include?("uid")
self.id = SecureRandom.random_number(36**10).to_s(36)
while !self.class.find_by(:uid, self.id).nil? do
self.id = SecureRandom.random_number(36**10).to_s(36)
end
end
end
ActiveRecord::Base.send(:include, ActiveRecordUIDExtension)
ActiveRecord::Base.send(:before_create, :generate_uid)
activerecord (4.1.1)
activemodel (= 4.1.1)
activesupport (= 4.1.1)
arel (~> 5.0.0)
答案 0 :(得分：2)
你的mixin没有任何意义。这部分就是导致错误的SQL：
self.class.find_by(:uid, self.id)
由于您正在告诉它，因此产生了无效的SQL。 find_by具有灵活的界面，因此必须进行一些解析以查看您是如何调用它的。当你说：
find_by(a, b)
参数解析可能假设您尝试使用此表单：
find_by('some_sql_snippet', placeholder_valid)
，如本例中的文档：
find_by("published_at < ?", 2.weeks.ago)
然后它可能会to_s第一个参数并扫描它占位符。当你说：
find_by(:uid, self.id)
您最终会被:uid.to_s和self.id忽略，因为该字符串中没有占位符。这可以解释为什么你在SQL中看到where ('uid')。
修复你的mixin有意义：
self.class.find_by(:uid => self.id)
或更好，切换到exists?以避免构建整个模型实例，只是为了查看数据库中是否有一行：
self.class.where(:uid => self.id).exists?
self.class.exists?(:uid => self.id)