Connect to database if not connected

[bijalhopkins]

Fix for this issue #308 (comment)

[mceachen]

Thanks for the PR!

This is partially reverting a recent commit--let's make sure we're addressing everyone's use cases before merging (see #305)

[n-rodriguez]

Hi! As I was suspecting it breaks when the DB don't exist, for example during tests on a real app :

   ✔ 03 nicolas@localhost 8.502s
      04 ~/.rvm/bin/rvm 2.5.1 do bundle exec rake db:create
      04 Unable to connect to a database. Globalize skipped ignoring columns of translated attributes.
      04 Unable to connect to a database. Globalize skipped ignoring columns of translated attributes.
      04 rake aborted!
      04 PG::ConnectionBad: FATAL:  la base de données « concerto » n'existe pas
      04 /home/nicolas/.rvm/gems/ruby-2.5.1/gems/pg-1.0.0/lib/pg.rb:56:in `initialize'
      04 /home/nicolas/.rvm/gems/ruby-2.5.1/gems/pg-1.0.0/lib/pg.rb:56:in `new'
      04 /home/nicolas/.rvm/gems/ruby-2.5.1/gems/pg-1.0.0/lib/pg.rb:56:in `connect'
      04 /home/nicolas/.rvm/gems/ruby-2.5.1/gems/activerecord-5.2.0/lib/active_record/connection_adapters/postgresql_adapter.rb:684:in `connect'
      04 /home/nicolas/.rvm/gems/ruby-2.5.1/gems/activerecord-5.2.0/lib/active_record/connection_adapters/postgresql_adapter.rb:215:in `initialize'
      04 /home/nicolas/.rvm/gems/ruby-2.5.1/gems/activerecord-5.2.0/lib/active_record/connection_adapters/postgresql_adapter.rb:40:in `new'
      04 /home/nicolas/.rvm/gems/ruby-2.5.1/gems/activerecord-5.2.0/lib/active_record/connection_adapters/postgresql_adapter.rb:40:in `postgresql_connection'
      04 /home/nicolas/.rvm/gems/ruby-2.5.1/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:809:in `new_connection'
      04 /home/nicolas/.rvm/gems/ruby-2.5.1/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:853:in `checkout_new_connection'
      04 /home/nicolas/.rvm/gems/ruby-2.5.1/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:832:in `try_to_checkout_new_connection'
      04 /home/nicolas/.rvm/gems/ruby-2.5.1/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:793:in `acquire_connection'
      04 /home/nicolas/.rvm/gems/ruby-2.5.1/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:521:in `checkout'
      04 /home/nicolas/.rvm/gems/ruby-2.5.1/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:380:in `connection'
      04 /home/nicolas/.rvm/gems/ruby-2.5.1/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:1008:in `retrieve_connection'
      04 /home/nicolas/.rvm/gems/ruby-2.5.1/gems/activerecord-5.2.0/lib/active_record/connection_handling.rb:118:in `retrieve_connection'
      04 /home/nicolas/.rvm/gems/ruby-2.5.1/gems/activerecord-5.2.0/lib/active_record/connection_handling.rb:90:in `connection'
      04 /home/nicolas/PROJECTS/CONCERTO/concerto/vendor/gems/closure_tree/lib/closure_tree/support_flags.rb:22:in `order_is_numeric?'
      04 /home/nicolas/PROJECTS/CONCERTO/concerto/vendor/gems/closure_tree/lib/closure_tree/support.rb:28:in `initialize'
      04 /home/nicolas/PROJECTS/CONCERTO/concerto/vendor/gems/closure_tree/lib/closure_tree/has_closure_tree.rb:16:in `new'
      04 /home/nicolas/PROJECTS/CONCERTO/concerto/vendor/gems/closure_tree/lib/closure_tree/has_closure_tree.rb:16:in `has_closure_tree'
      04 /home/nicolas/PROJECTS/CONCERTO/concerto/app/models/page.rb:45:in `<class:Page>'
      04 /home/nicolas/PROJECTS/CONCERTO/concerto/app/models/page.rb:24:in `<main>'

As you can notice, Globalize gem has the same chicken and egg issue :

      04 Unable to connect to a database. Globalize skipped ignoring columns of translated attributes.
      04 Unable to connect to a database. Globalize skipped ignoring columns of translated attributes.

It's here : https://github.com/globalize/globalize/blob/master/lib/globalize/active_record/act_macro.rb#L44

[mceachen]

@n-rodriguez thanks a bunch for taking the time to research that. Can you think of a way to write a breaking test so this can be automated?

[n-rodriguez]

Well... this one is a bit complicated : Ruby module inclusion depends on the return value of order_is_numeric? :

closure_tree/lib/closure_tree/has_closure_tree.rb

Line 31 in 0f405ca

include ClosureTree::NumericDeterministicOrdering if _ct.order_is_numeric?

[n-rodriguez]

The method is evaluated only once (I think) : at boot time.

[n-rodriguez]

So the patch I've made is wrong because it will always return false and thus the module won't be included.

[n-rodriguez]

In fact I don't why this part should be dynamic...

[n-rodriguez]

We make a DB query to check if the DB field is an integer... Well... (us) the developer should know in advance the field type and pass it as an option to has_closure_tree method.
It's just a suggestion as I don't know the implications of such a change ^^

[n-rodriguez]

By reading the doc (https://github.com/ClosureTree/closure_tree#deterministic-ordering) it seems legit to get the info from the DB... but sometimes a good duplication is better than a bad abstraction ^^

[n-rodriguez]

This one should fix it for good :) #311

[n-rodriguez]

Hello! I think this issue can be closed as it's fixed by #311

[bijalhopkins]

👍