Currently Active Record can be configured via the environment variable `DATABASE_URL` or by manually injecting a hash of values which is what Rails does, reading in `database.yml` and setting Active Record appropriately. Active Record expects to be able to use `DATABASE_URL` without the use of Rails, and we cannot rip out this functionality without deprecating. This presents a problem though when both config is set, and a `DATABASE_URL` is present. Currently the `DATABASE_URL` should "win" and none of the values in `database.yml` are used. This is somewhat unexpected to me if I were to set values such as `pool` in the `production:` group of `database.yml` they are ignored.
There are many ways that active record initiates a connection today:
- Stand Alone (without rails)
- `rake db:<tasks>`
- ActiveRecord.establish_connection
- With Rails
- `rake db:<tasks>`
- `rails <server> | <console>`
- `rails dbconsole`
We should make all of these behave exactly the same way. The best way to do this is to put all of this logic in one place so it is guaranteed to be used.
Here is my prosed matrix of how this behavior should work:
```
No database.yml
No DATABASE_URL
=> Error
```
```
database.yml present
No DATABASE_URL
=> Use database.yml configuration
```
```
No database.yml
DATABASE_URL present
=> use DATABASE_URL configuration
```
```
database.yml present
DATABASE_URL present
=> Merged into `url` sub key. If both specify `url` sub key, the `database.yml` `url`
sub key "wins". If other paramaters `adapter` or `database` are specified in YAML,
they are discarded as the `url` sub key "wins".
```
### Implementation
Current implementation uses `ActiveRecord::Base.configurations` to resolve and merge all connection information before returning. This is achieved through a utility class: `ActiveRecord::ConnectionHandling::MergeAndResolveDefaultUrlConfig`.
To understand the exact behavior of this class, it is best to review the behavior in activerecord/test/cases/connection_adapters/connection_handler_test.rb though it should match the above proposal.
The build is broken: https://travis-ci.org/rails/rails/builds/15824530
This commit fixes it.
The problem: Sqlite expects the `database` part to be an absolute path. That prompted this change to be committed to master: fbb79b517f
This change provides correct behavior. Unfortunately tests were introduced in 971d5107cd that were relying on the incorrect behavior. We can avoid the fix by changing to another database url such as `mysql` or `postgresql`
In addition to fixing the failure, the assertions are changed so that the "expected" value comes before "actual" value.
Allow environment name to start with a substring of the default
environment names.
For example: tes, pro, prod, dev, devel, etc.
Fixing identation.
Adding test for Rails::Console.parse_arguments method.
Fix issue 8628 for Rails::DBConsole.
When using sqlite3 it was attempting to find the database file based on
Rails.root, the problem is that Rails.root is not always present because
we try to first manually load "config/database.yml" instead of loading
the entire app, to make "rails db" faster.
This means that when we're in the root path of the app, calling "rails db"
won't allow us to use Rails.root, making the command fail for sqlite3
with the error:
./rails/commands/dbconsole.rb:62:in `start':
undefined method `root' for Rails:Module (NoMethodError)
The fix is to simply not pass any dir string to File.expand_path, which
will make it use the current directory of the process as base, or the
root path of the app, which is what we want.
When we are in any other subdirectory, calling "rails db" should work
just fine, because "config/database.yml" won't be found, thus "rails db"
will fallback to loading the app, making Rails.root available.
Closes#8257.
Rails uses sqlit3 db file with a path relative to the rails root. It
allows to execute server not from rails root only. For example you
can fire `./spec/dummy/script/rails s` to start dummy application
server if you develop some engine gem.
Now the `rails db` command uses relative paths also and you can explore
your dummy db via `./spec/dummy/script/rails db` command.
