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rails--rails/activerecord/lib/active_record/schema.rb
Rafael Mendonça França 2d763738d9
Dump the database schema containing the current Rails version
Since https://github.com/rails/rails/pull/42297, Rails now generates
datetime columns on MySQL with a default precision of 6. This means
that users upgrading to Rails 7.0 from 6.1, when loading the database
schema, would get the new precision value, which would not match the
production schema.

To avoid problems like this in the future,
Rails will now freeze `ActiveRecord::Schema` class to
be the 7.0 implementation, and will allow access to other version
using the same mechanism of `ActiveRecord::Migration`.

The schema dumper will generate the new format which will include the
Rails version and will look like this:

```
ActiveRecord::Schema[7.0].define
```

Related to #43934 and #43909.
2022-02-07 18:58:36 +00:00

76 lines
2.4 KiB
Ruby

# frozen_string_literal: true
module ActiveRecord
# = Active Record \Schema
#
# Allows programmers to programmatically define a schema in a portable
# DSL. This means you can define tables, indexes, etc. without using SQL
# directly, so your applications can more easily support multiple
# databases.
#
# Usage:
#
# ActiveRecord::Schema[7.0].define do
# create_table :authors do |t|
# t.string :name, null: false
# end
#
# add_index :authors, :name, :unique
#
# create_table :posts do |t|
# t.integer :author_id, null: false
# t.string :subject
# t.text :body
# t.boolean :private, default: false
# end
#
# add_index :posts, :author_id
# end
#
# ActiveRecord::Schema is only supported by database adapters that also
# support migrations, the two features being very similar.
class Schema < Migration::Current
module Definition
extend ActiveSupport::Concern
module ClassMethods
# Eval the given block. All methods available to the current connection
# adapter are available within the block, so you can easily use the
# database definition DSL to build up your schema (
# {create_table}[rdoc-ref:ConnectionAdapters::SchemaStatements#create_table],
# {add_index}[rdoc-ref:ConnectionAdapters::SchemaStatements#add_index], etc.).
#
# The +info+ hash is optional, and if given is used to define metadata
# about the current schema (currently, only the schema's version):
#
# ActiveRecord::Schema[7.0].define(version: 2038_01_19_000001) do
# ...
# end
def define(info = {}, &block)
new.define(info, &block)
end
end
def define(info, &block) # :nodoc:
instance_eval(&block)
if info[:version].present?
connection.schema_migration.create_table
connection.assume_migrated_upto_version(info[:version])
end
ActiveRecord::InternalMetadata.create_table
ActiveRecord::InternalMetadata[:environment] = connection.migration_context.current_environment
end
end
include Definition
def self.[](version)
@class_for_version ||= {}
@class_for_version[version] ||= Class.new(Migration::Compatibility.find(version)) do
include Definition
end
end
end
end