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#63 ✓ committed
Ian White

[BUG] rake db:create and observers

Reported by Ian White | April 29th, 2008 @ 07:29 PM

If you have an observer, then doing rake db:create in some circumstances (one is described below) causes rail to die with 'unknown database'.

Obviously a circular dependency problem.

I've been poking around the test suite, and can't seem to find the right place for testing this, can anyone offer any pointers?

The problem can be reproduced with (fresh rails app, with dbs wiped)

config/environment.rb:
  config.active_record.observers = :user_observer

app/models/user.rb
  class User < ActiveRecord::Base
    has_many :posts, :conditions => ['posts.published = ?', true], :order => 'updated_at DESC', :dependent => :destroy
  end

app/models/user_observer.rb
  class UserObserver < ActiveRecord::Observer
  end

Comments and changes to this ticket

  • Michael Koziarski

    Michael Koziarski May 4th, 2008 @ 01:47 AM

    Can you post a stack trace by using rake --trace.

  • Michael Koziarski

    Michael Koziarski May 4th, 2008 @ 01:47 AM

    • Assigned user set to “Michael Koziarski”
  • Ian White

    Ian White May 4th, 2008 @ 09:39 AM

    Stack trace below

    I've attached a git diff of what I had to add to a fresh rails app (6a6b439 Sun Apr 20 12:57:36 2008 +0800) to get the problem to occur.

    I'd be happy to investigate, but couldn't find the obvious place to start adding tests.

    
    ~/dev/sandbox/ticket63(master)$ rake db:create --trace
    (in /Users/ian/dev/sandbox/ticket63)
    ** Invoke db:create (first_time)
    ** Invoke environment (first_time)
    ** Execute environment
    rake aborted!
    Unknown database 'ticket63_development'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb:505:in `real_connect'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb:505:in `connect'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb:183:in `initialize'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb:88:in `new'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb:88:in `mysql_connection'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb:292:in `send'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb:292:in `connection='
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb:260:in `retrieve_connection'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb:78:in `connection'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/base.rb:2067:in `quote_bound_value'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/base.rb:2035:in `replace_bind_variables'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/base.rb:2035:in `gsub'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/base.rb:2035:in `replace_bind_variables'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/base.rb:2024:in `sanitize_sql_array'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/base.rb:1921:in `sanitize_sql'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/associations.rb:1249:in `configure_dependency_for_has_many'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/associations.rb:700:in `has_many'
    /Users/ian/dev/sandbox/ticket63/app/models/user.rb:2
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/dependencies.rb:214:in `load_without_new_constant_marking'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/dependencies.rb:214:in `load_file'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/dependencies.rb:353:in `new_constants_in'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/dependencies.rb:213:in `load_file'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/dependencies.rb:94:in `require_or_load'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/dependencies.rb:259:in `load_missing_constant'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/dependencies.rb:466:in `const_missing'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/dependencies.rb:478:in `const_missing'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/inflector.rb:271:in `constantize'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/core_ext/string/inflections.rb:143:in `constantize'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/observer.rb:157:in `observed_class'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/observer.rb:183:in `observed_classes'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/observer.rb:166:in `initialize'
    /opt/local/lib/ruby/1.8/singleton.rb:95:in `new'
    /opt/local/lib/ruby/1.8/singleton.rb:95:in `instance'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/observer.rb:38:in `instantiate_observers'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/observer.rb:36:in `each'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activerecord/lib/active_record/observer.rb:36:in `instantiate_observers'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/actionpack/lib/action_controller/dispatcher.rb:26:in `define_dispatcher_callbacks'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/callbacks.rb:177:in `call'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/callbacks.rb:177:in `evaluate_method'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/callbacks.rb:161:in `call'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/callbacks.rb:90:in `run'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/callbacks.rb:90:in `each'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/callbacks.rb:90:in `send'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/callbacks.rb:90:in `run'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/callbacks.rb:272:in `run_callbacks'
    /Users/ian/dev/sandbox/ticket63/config/../vendor/rails/railties/lib/initializer.rb:460:in `send'
    /Users/ian/dev/sandbox/ticket63/config/../vendor/rails/railties/lib/initializer.rb:460:in `prepare_dispatcher'
    /Users/ian/dev/sandbox/ticket63/config/../vendor/rails/railties/lib/initializer.rb:146:in `process'
    /Users/ian/dev/sandbox/ticket63/config/../vendor/rails/railties/lib/initializer.rb:89:in `send'
    /Users/ian/dev/sandbox/ticket63/config/../vendor/rails/railties/lib/initializer.rb:89:in `run'
    /Users/ian/dev/sandbox/ticket63/config/environment.rb:13
    /opt/local/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require'
    /opt/local/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:27:in `require'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/dependencies.rb:508:in `require'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/dependencies.rb:353:in `new_constants_in'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/activesupport/lib/active_support/dependencies.rb:508:in `require'
    /Users/ian/dev/sandbox/ticket63/vendor/rails/railties/lib/tasks/misc.rake:3
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:546:in `call'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:546:in `execute'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:541:in `each'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:541:in `execute'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:508:in `invoke_with_call_chain'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:501:in `synchronize'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:501:in `invoke_with_call_chain'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:518:in `invoke_prerequisites'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:1183:in `each'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:1183:in `send'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:1183:in `each'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:515:in `invoke_prerequisites'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:507:in `invoke_with_call_chain'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:501:in `synchronize'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:501:in `invoke_with_call_chain'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:494:in `invoke'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:1931:in `invoke_task'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:1909:in `top_level'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:1909:in `each'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:1909:in `top_level'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:1948:in `standard_exception_handling'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:1903:in `top_level'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:1881:in `run'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:1948:in `standard_exception_handling'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/lib/rake.rb:1878:in `run'
    /opt/local/lib/ruby/gems/1.8/gems/rake-0.8.1/bin/rake:31
    /opt/local/bin/rake:16:in `load'
    /opt/local/bin/rake:16
    
    
  • Michael Koziarski

    Michael Koziarski May 4th, 2008 @ 09:44 AM

    So it's trying to generate the finder sql for your has_many association, and needs the database connection in order to quote the sql,

    I'm not sure how easy this will be to patch, don't worry about the tests initially, try to figure out the solution ;)

  • Ian White

    Ian White May 4th, 2008 @ 10:09 AM

    Well, a really trivial 'fix' is to just rescue observer instantiation, and log the error (patch given on right)

    Given that this is a bootstrapping dependency problem, this might be appropraite. It's a bit icky though.

    A more sophisticated version of this approach would be to have a config setting 'allow_observer_instatiation_failure', which is set by various bootstrapping tasks (like db:create, or db:migrate). Also, being more discriminating on error catching would be useful.

    Could you advise on whether this general approach (ignore snafus when bootstrapping) is likely to get traction? It could hide sins if used badly. It would be in effect saying 'bootstrapping is different to running the app'

  • Ian White

    Ian White May 4th, 2008 @ 10:20 AM

    Even simpler: rescue the bootstrapping tasks' db loading

    Given that this is an edge case (trying to load up framework when db

    doesn't yet exist), it makes sense to allow for snafus that result

    from this.

  • Joshua Peek

    Joshua Peek July 17th, 2008 @ 01:08 AM

    • State changed from “new” to “open”
    • Tag set to activerecord, bug

    Koz, you going apply this?

  • Gerrit Kaiser

    Gerrit Kaiser October 6th, 2008 @ 01:52 AM

    This one trips me up a lot aswell. Pretty much makes db:create and co unusable for me (I’m heavily using branch-specific databases so have a need to create them even after the initial app generation).

    I don’t really see why db:create would depend on the whole environment at all… Couldn’t it just load the database.yml and use ActiveRecord independent of the app? That would reduce the startup time for those tasks aswell.

  • Michael Koziarski

    Michael Koziarski October 6th, 2008 @ 01:05 PM

    That sounds like a much nicer fix, if you can make those tasks just read the yml file, (and some how know the RAILS_ENV) then we solve most of these issues.

  • Gerrit Kaiser

    Gerrit Kaiser October 22nd, 2008 @ 05:22 AM

    • Tag changed from activerecord, bug to activerecord, bug, create_database, databases.rake, patch, rake

    whipped up a patch against a03e2b356c66ddc8809fa2b23a2a7d652f173b8b that won’t load the full environment for db:create:* and db:drop but instead just performs the minium config loading necessary.

    successfully manually tested on a skeleton rails app (didn’t see any examples of how to automatically test rake tasks)

  • Aliaksey Kandratsenka

    Aliaksey Kandratsenka November 28th, 2008 @ 03:41 PM

    After Gerrit's patch db:drop stopped working for mysql. That's because mysql connection wasn't established before call to #drop_database. I'm attaching a trivial fix.

  • Aliaksey Kandratsenka

    Aliaksey Kandratsenka November 28th, 2008 @ 03:42 PM

    Ah. I forgot to mention that Gerrit's patch fixed the problem for us.

  • Repository

    Repository December 1st, 2008 @ 08:40 PM

    • State changed from “open” to “committed”

    (from [a0bc480e1ddcaa015927c2d941e7b96a8ce4f6fa]) establish mysql connection before dropping database

    Signed-off-by: Michael Koziarski michael@koziarski.com [#63 state:committed] http://github.com/rails/rails/co...

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