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`rename_index`: add the new index before removing the old one.

This prevents the following error when a MySQL index on a foreign key
column is renamed:

```
ActiveRecord::StatementInvalid: Mysql2::Error: Cannot drop index 'index_engines_on_car_id': needed in a foreign key constraint: DROP INDEX `index_engines_on_car_id` ON `engines`
```

refs: #13038.
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1 parent e4c0a22 commit 6eba8d27e6feecca88303df6500ef6b376344e29 @senny senny committed Nov 26, 2013
@@ -1,9 +1,17 @@
+* `rename_index` adds the new index before removing the old one. This allows
+ to rename indexes on columns with a foreign key and prevents the following error:
+
+ `Cannot drop index 'index_engines_on_car_id': needed in a foreign key constraint`
+
+ *Cody Cutrer*, *Yves Senn*
+
* Raise `ActiveRecord::RecordNotDestroyed` when a replaced child marked with `dependent: destroy` fails to be destroyed.
Fix #12812
*Brian Thomas Storti*
+
* Fix validation on uniqueness of empty association.
*Evgeny Li*
@@ -558,8 +558,8 @@ def rename_index(table_name, old_name, new_name)
# this is a naive implementation; some DBs may support this more efficiently (Postgres, for instance)
old_index_def = indexes(table_name).detect { |i| i.name == old_name }
return unless old_index_def
- remove_index(table_name, :name => old_name)
- add_index(table_name, old_index_def.columns, :name => new_name, :unique => old_index_def.unique)
+ add_index(table_name, old_index_def.columns, name: new_name, unique: old_index_def.unique)
+ remove_index(table_name, name: old_name)
end
def index_name(table_name, options) #:nodoc:
@@ -4,22 +4,35 @@ module ActiveRecord
module ConnectionAdapters
class Mysql2Adapter
class SchemaMigrationsTest < ActiveRecord::TestCase
- def test_initializes_schema_migrations_for_encoding_utf8mb4
- conn = ActiveRecord::Base.connection
+ def test_renaming_index_on_foreign_key
+ connection.add_index "engines", "car_id"
+ connection.execute "ALTER TABLE engines ADD CONSTRAINT fk_engines_cars FOREIGN KEY (car_id) REFERENCES cars(id)"
+
+ connection.rename_index("engines", "index_engines_on_car_id", "idx_renamed")
+ assert_equal ["idx_renamed"], connection.indexes("engines").map(&:name)
+ ensure
+ connection.execute "ALTER TABLE engines DROP FOREIGN KEY fk_engines_cars"
+ end
+ def test_initializes_schema_migrations_for_encoding_utf8mb4
smtn = ActiveRecord::Migrator.schema_migrations_table_name
- conn.drop_table(smtn) if conn.table_exists?(smtn)
+ connection.drop_table(smtn) if connection.table_exists?(smtn)
- config = conn.instance_variable_get(:@config)
+ config = connection.instance_variable_get(:@config)
original_encoding = config[:encoding]
config[:encoding] = 'utf8mb4'
- conn.initialize_schema_migrations_table
+ connection.initialize_schema_migrations_table
- assert conn.column_exists?(smtn, :version, :string, limit: Mysql2Adapter::MAX_INDEX_LENGTH_FOR_UTF8MB4)
+ assert connection.column_exists?(smtn, :version, :string, limit: Mysql2Adapter::MAX_INDEX_LENGTH_FOR_UTF8MB4)
ensure
config[:encoding] = original_encoding
end
+
+ private
+ def connection
+ @connection ||= ActiveRecord::Base.connection
+ end
end
end
end

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