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rails--rails/activerecord/test/cases/legacy_configurations_test.rb
Eileen Uchitelle fdf3f0b930 Refactors Active Record connection management
While the three-tier config makes it easier to define databases for
multiple database applications, it quickly became clear to offer full
support for multiple databases we need to change the way the connections
hash was handled.

A three-tier config means that when Rails needed to choose a default
configuration (in the case a user doesn't ask for a specific
configuration) it wasn't clear to Rails which the default was. I
[bandaid fixed this so the rake tasks could work](#32271) but that fix
wasn't correct because it actually doubled up the configuration hashes.

Instead of attemping to manipulate the hashes @tenderlove and I decided
that it made more sense if we converted the hashes to objects so we can
easily ask those object questions. In a three tier config like this:

```
development:
  primary:
    database: "my_primary_db"
  animals:
    database; "my_animals_db"
```

We end up with an object like this:

```
  @configurations=[
    #<ActiveRecord::DatabaseConfigurations::HashConfig:0x00007fd1acbded10
      @env_name="development",@spec_name="primary",
      @config={"adapter"=>"sqlite3", "database"=>"db/development.sqlite3"}>,
    #<ActiveRecord::DatabaseConfigurations::HashConfig:0x00007fd1acbdea90
      @env_name="development",@spec_name="animals",
      @config={"adapter"=>"sqlite3", "database"=>"db/development.sqlite3"}>
]>
```

The configurations setter takes the database configuration set by your
application and turns them into an
`ActiveRecord::DatabaseConfigurations` object that has one getter -
`@configurations` which is an array of all the database objects.

The configurations getter returns this object by default since it acts
like a hash in most of the cases we need. For example if you need to
access the default `development` database we can simply request it as we
did before:

```
ActiveRecord::Base.configurations["development"]
```

This will return primary development database configuration hash:

```
{ "database" => "my_primary_db" }
```

Internally all of Active Record has been converted to use the new
objects. I've built this to be backwards compatible but allow for
accessing the hash if needed for a deprecation period. To get the
original hash instead of the object you can either add `to_h` on the
configurations call or pass `legacy: true` to `configurations.

```
ActiveRecord::Base.configurations.to_h
=> { "development => { "database" => "my_primary_db" } }

ActiveRecord::Base.configurations(legacy: true)
=> { "development => { "database" => "my_primary_db" } }
```

The new configurations object allows us to iterate over the Active
Record configurations without losing the known environment or
specification name for that configuration. You can also select all the
configs for an env or env and spec. With this we can always ask
any object what environment it belongs to:

```
db_configs = ActiveRecord::Base.configurations.configurations_for("development")
=> #<ActiveRecord::DatabaseConfigurations:0x00007fd1acbdf800
  @configurations=[
    #<ActiveRecord::DatabaseConfigurations::HashConfig:0x00007fd1acbded10
      @env_name="development",@spec_name="primary",
      @config={"adapter"=>"sqlite3", "database"=>"db/development.sqlite3"}>,
    #<ActiveRecord::DatabaseConfigurations::HashConfig:0x00007fd1acbdea90
      @env_name="development",@spec_name="animals",
      @config={"adapter"=>"sqlite3", "database"=>"db/development.sqlite3"}>
]>

db_config.env_name
=> "development"

db_config.spec_name
=> "primary"

db_config.config
=> { "adapter"=>"sqlite3", "database"=>"db/development.sqlite3" }
```

The configurations object is more flexible than the configurations hash
and will allow us to build on top of the connection management in order
to add support for primary/replica connections, sharding, and
constructing queries for associations that live in multiple databases.
2018-08-30 10:06:45 -04:00

43 lines
1.4 KiB
Ruby

# frozen_string_literal: true
require "cases/helper"
module ActiveRecord
class LegacyConfigurationsTest < ActiveRecord::TestCase
def test_can_turn_configurations_into_a_hash
assert ActiveRecord::Base.configurations.to_h.is_a?(Hash), "expected to be a hash but was not."
assert_equal ["arunit", "arunit2", "arunit_without_prepared_statements"].sort, ActiveRecord::Base.configurations.to_h.keys.sort
end
def test_each_is_deprecated
assert_deprecated do
ActiveRecord::Base.configurations.each do |db_config|
assert_equal "primary", db_config.spec_name
end
end
end
def test_first_is_deprecated
assert_deprecated do
db_config = ActiveRecord::Base.configurations.first
assert_equal "arunit", db_config.env_name
assert_equal "primary", db_config.spec_name
end
end
def test_fetch_is_deprecated
assert_deprecated do
db_config = ActiveRecord::Base.configurations.fetch("arunit").first
assert_equal "arunit", db_config.env_name
assert_equal "primary", db_config.spec_name
end
end
def test_values_are_deprecated
config_hashes = ActiveRecord::Base.configurations.configurations.map(&:config)
assert_deprecated do
assert_equal config_hashes, ActiveRecord::Base.configurations.values
end
end
end
end