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Diffstat (limited to 'doc/development/rails_initializers.md')
| -rw-r--r-- | doc/development/rails_initializers.md | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/doc/development/rails_initializers.md b/doc/development/rails_initializers.md index ee73dac2b72..9bf4109f1cb 100644 --- a/doc/development/rails_initializers.md +++ b/doc/development/rails_initializers.md @@ -20,3 +20,21 @@ Some examples where you would need to do this are: 1. Modifying Rails' `config.autoload_paths` 1. Changing configuration that Zeitwerk uses, for example, inflections + +## Database connections in initializers + +Ideally, database connections are not opened from Rails initializers. Opening a +database connection (e.g. checking the database exists, or making a database +query) from an initializer means that tasks like `db:drop`, and +`db:test:prepare` will fail because an active session prevents the database from +being dropped. + +To help detect when database connections are opened from initializers, we now +warn in stderr. For example: + +```shell +DEPRECATION WARNING: Database connection should not be called during initializers (called from block in <module:HasVariable> at app/models/concerns/ci/has_variable.rb:22) +``` + +If you wish to print out the full backtrace, set the +`DEBUG_INITIALIZER_CONNECTIONS` environment variable. |