Migrate using decorators

[antoine-pous]

Issue type:

[ ] question
[ ] bug report
[x] feature request
[ ] documentation issue

Database system/driver:

[ ] cordova
[ ] mongodb
[ ] mssql
[ ] mysql / mariadb
[ ] oracle
[ ] postgres
[ ] cockroachdb
[ ] sqlite
[ ] sqljs
[ ] react-native
[ ] expo
[x] any

TypeORM version:

[ ] latest
[x] @next
[ ] 0.x.x (or put your version here)

Request:
Actually when we migrate we mostly use queryRunner.query which run raw SQL queries. But it would be awesome to be able to use decorators instead. Then a migration can be even more readable and it's code will become compliant with it's model.

Here's an example:
We add an index to a table, then just do

Actual way to migrate:

class addIndexToTable123456789 {
  up(queryRunner: QueryRunner): Promise<void> {
    await queryRunner.query(`CREATE UNIQUE INDEX "IDX_1234" ON "schema"."table" ("col1", "col2", "col3") `)
  }

  down(): Promise<void> {
    await queryRunner.query(`DROP INDEX "schema"."IDX_1234"`)
  }
}

Requested changes:

@migrate
class addIndexToTable123456789 {
  @up()
  @addIndex('indexName', 'tableName', ['col1', 'col2', 'col3'], { unique: true })

  @down()
  @dropIndex('indexName', 'tableName')
}

The main goal is avoiding raw strings and use a minimalist code to perform migrations when it's possible, when we can't we can still use queryRunner.

[pconerly]

@antoine-pous I like the syntax change for addIndex, but I think that the @up() is going too far? Having up and down organized into two separate methods is a nice way to organize, and it's similar to other migration frameworks.

[antoine-pous]

@pconerly i agree with you, this can become painful :)

@migrate
class addIndexToTable123456789 {
  public up(): Promise<void> {
    @addIndex('indexName', 'tableName', ['col1', 'col2', 'col3'], { unique: true })
  }

  public down(): Promise<void> {
    @dropIndex('indexName', 'tableName')
  }
}

Seem good too, maybe allowing both and let the dev decide depending his migration can be the best approach 🤔

[MurkyMeow]

You could save 2 characters by not putting that @ symbol in front of each function call 😉.

[imnotjames]

You can use queryRunner.createIndex to do this - sure, it's not a decorator, but it's an API that is EFFECTIVELY what you're describing! :)