Rails给出了关系表的问题，SQLite3::SQLException:没有这样的列

Question

似乎找不到解决方案。我有一个关系表BlabsUser，我正试图从中查找并销毁一个记录。我在做这个：

BlabsUser.find_by_user_id_and_blab_id(1,29).destroy

得到这个可爱的错误：

BlabsUser Load (0.2ms)  SELECT "blabs_users".* FROM "blabs_users" WHERE "blabs_users"."user_id" = 1 AND "blabs_users"."blab_id" = 29 LIMIT 1
Could not log "sql.active_record" event. NoMethodError: undefined method `name' for nil:NilClass
SQLite3::SQLException: no such column: blabs_users.: DELETE FROM "blabs_users" WHERE "blabs_users"."" = ?
ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column: blabs_users.: DELETE FROM "blabs_users" WHERE "blabs_users"."" = ?
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/sqlite3-1.3.5/lib/sqlite3/database.rb:91:in `initialize'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/sqlite3-1.3.5/lib/sqlite3/database.rb:91:in `new'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/sqlite3-1.3.5/lib/sqlite3/database.rb:91:in `prepare'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/connection_adapters/sqlite_adapter.rb:234:in `block in exec_query'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract_adapter.rb:244:in `block in log'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activesupport-3.1.3/lib/active_support/notifications/instrumenter.rb:21:in `instrument'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract_adapter.rb:239:in `log'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/connection_adapters/sqlite_adapter.rb:223:in `exec_query'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/connection_adapters/sqlite_adapter.rb:249:in `exec_delete'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract/database_statements.rb:101:in `delete'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract/query_cache.rb:14:in `delete'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/relation.rb:351:in `delete_all'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/persistence.rb:94:in `destroy'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/locking/optimistic.rb:119:in `destroy'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/callbacks.rb:254:in `block in destroy'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activesupport-3.1.3/lib/active_support/callbacks.rb:390:in `_run_destroy_callbacks'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activesupport-3.1.3/lib/active_support/callbacks.rb:81:in `run_callbacks'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/callbacks.rb:254:in `destroy'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/transactions.rb:236:in `block in destroy'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/transactions.rb:295:in `block in with_transaction_returning_status'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/connection_adapters/abstract/database_statements.rb:192:in `transaction'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/transactions.rb:208:in `transaction'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/transactions.rb:293:in `with_transaction_returning_status'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.3/lib/active_record/transactions.rb:236:in `destroy'
    from (irb):1
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.1.3/lib/rails/commands/console.rb:45:in `start'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.1.3/lib/rails/commands/console.rb:8:in `start'
    from /Users/dylandrop/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.1.3/lib/rails/commands.rb:40:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'

为什么它在寻找一个名为blabs_users的列？为什么它不只是在我的blabs_users表中查找一条记录？此外，更重要的是，我该如何解决这个问题？

编辑：我也尝试过同样的问题：

BlabsUser.destroy_all(:blab_id => 29, :user_id => 1)

根据请求编辑2：我的型号只是

class BlabsUser < ActiveRecord::Base
end

迁移只是

class BlabsUsers < ActiveRecord::Migration
  def self.up
      create_table :blabs_users, :id => false, :force => true do |t|
          t.integer :user_id
          t.integer :blab_id
          t.timestamps
      end
  end
  def self.down
      drop_table :blabs_users
  end
end

Answer 1

ActiveRecord在很大程度上取决于是否有一个唯一的键（通常是表的主键）。由于您明确没有定义一个键（:id => false），我强烈怀疑您的问题与此有关。

destroy()也被记录为销毁具有给定id的对象（或多个对象），这强烈表明它需要使用该唯一id。