NoExistingObject exception when using Sequel::Model.plugin timestamps and touch

Question

As part of a project, I have created a Session model to store the dates when it was first created and updated (using the timestamps plugin provided by Sequel). This is to facilitate server-side handling of session timeouts. The updated_at column can be updated using Sequel's touch plugin, which provides an equivalent method.

However, when trying to use it, I receive the following error

Sequel::NoExistingObject: Attempt to update object did not result in a single row modification (SQL: UPDATE sessions SET updated_at = '2016-07-01 12:17:06.373469' WHERE (id = 14))
from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sequel-4.35.0/lib/sequel/model/base.rb:2018:in _update' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sequel-4.35.0/lib/sequel/model/base.rb:2011:in_update_columns'
from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sequel-4.35.0/lib/sequel/model/base.rb:1965:in block (2 levels) in _save' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sequel-4.35.0/lib/sequel/model/base.rb:1146:inaround_update'
from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sequel-4.35.0/lib/sequel/model/base.rb:1949:in block in _save' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sequel-4.35.0/lib/sequel/model/base.rb:1146:inaround_save'
from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sequel-4.35.0/lib/sequel/model/base.rb:1935:in _save' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sequel-4.35.0/lib/sequel/model/base.rb:1587:inblock (2 levels) in save'
from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sequel-4.35.0/lib/sequel/model/base.rb:2089:in block in checked_transaction' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sequel-4.35.0/lib/sequel/database/transactions.rb:163:in_transaction'
from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sequel-4.35.0/lib/sequel/database/transactions.rb:138:in block in transaction' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sequel-4.35.0/lib/sequel/database/connecting.rb:251:inblock in synchronize'
from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sequel-4.35.0/lib/sequel/connection_pool/threaded.rb:105:in hold' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sequel-4.35.0/lib/sequel/database/connecting.rb:251:insynchronize'
from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sequel-4.35.0/lib/sequel/database/transactions.rb:104:in transaction' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/sequel-4.35.0/lib/sequel/model/base.rb:2089:inchecked_transaction'
... 7 levels...
from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/commands/console.rb:9:in start' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/commands/commands_tasks.rb:68:inconsole' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/commands/commands_tasks.rb:39:in run_command!' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/commands.rb:17:in' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in require' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:inblock in require' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:240:in load_dependency' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:inrequire' from /Users/[FILTERED USERNAME]/Sync/RubymineProjects/[FILTERED PROJECT NAME]/bin/rails:9:in <top (required)>' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:268:inload' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:268:in block in load' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:240:inload_dependency' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:268:in load' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/site_ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:inrequire' from /Users/[FILTERED USERNAME]/.rbenv/versions/2.3.1/lib/ruby/site_ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in require' from -e:1:in'

I have already tried using the Sequel::Model.update and Sequel::Model.update_all methods, but to no avail (receiving the same error).

What is intriguing is that I am able to run the SQL query produced above via the command line, with both SQLite and MySQL.

==== app/models/session.rb ====

class Session < Sequel::Model
  plugin :validation_helpers
  plugin :timestamps
  plugin :touch

  def before_update
    self.touch
  end

  def before_save
    Session.where(user_id: self.user_id).delete
  end

  def self.sweep(time = 2.hours)
    time = time.split.inject { |count, unit| count.to_i.send(unit) } if time.is_a?(String)
    Session.where("updated_at < '#{time.ago.to_s(:db)}' OR created_at < '#{1.day.ago.to_s(:db)}'").delete
  end

  def validates
    validates_presence [:user_id]
  end
end

Thanks advance for any help provided.

Jeremy Evans Jeremy Evans · Accepted Answer · 2016-07-01T14:38:43

def before_save
  Session.where(user_id: self.user_id).delete
end

This is going to delete all rows in the sessions table with the same user_id before saving the session, including the current row (if updating and not creating). If you only want to allow a single session, you should probably switch to using before_create. Also, don't forget to call super in your hooks.

NoExistingObject exception when using Sequel::Model.plugin timestamps and touch

1 Answers