Table indexes needlessly recreated when generating migrations

Issue type:

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

Database system/driver:

[ ] cordova [ ] mongodb [ ] mssql [ x] mysql / mariadb (using mysql 8) [ ] oracle [ ] postgres [ ] cockroachdb [ ] sqlite [ ] sqljs [ ] react-native [ ] expo

TypeORM version:

[ ] latest [ ] @next [x ] 0.2.19

Steps to reproduce or a small repository showing the problem:

1. Create models below
2. Generate and run a migration (generated code shown below).
3. Make no changes to the models
4. Generate another migration (generated code shown below)

Results: Migration drops and recreates many indexes

Expected: No changes in the migration since the model has not changed

Note that the only change in the migration seems to be from the index name REL_36c1bea209538ff07049dd748a in the initial creation of the table to IDX_36c1bea209538ff07049dd748a in the migration.

Models

@Entity({ name: 'users2' })
export class Users {
  @PrimaryGeneratedColumn()
  id!: string;
}

@Entity({ name: 'simple_example' })
@Unique(['userId', 'choice'])
export class SimpleExample {

  @PrimaryGeneratedColumn()
  id!: string;

  @Column({ name: 'user_id', nullable: false })
  userId!: UserID;

  @Column({ name: 'choice', nullable: false })
  choice!: number;

  @OneToOne(() => Users)
  @JoinColumn({ name: ReferralSurvey.columnNames.userId })
  user!: UserModel;
}

Initial migration

import {MigrationInterface, QueryRunner} from "typeorm";

export class createExample1574282003669 implements MigrationInterface {

    public async up(queryRunner: QueryRunner): Promise<any> {
        await queryRunner.query("CREATE TABLE `users2` (`id` int NOT NULL AUTO_INCREMENT, PRIMARY KEY (`id`)) ENGINE=InnoDB", undefined);
        await queryRunner.query("CREATE TABLE `simple_example` (`id` int NOT NULL AUTO_INCREMENT, `user_id` int NOT NULL, `choice` int NOT NULL, UNIQUE INDEX `IDX_a1ebc46dd9a46cf638f43239fe` (`user_id`, `choice`), UNIQUE INDEX `REL_36c1bea209538ff07049dd748a` (`user_id`), PRIMARY KEY (`id`)) ENGINE=InnoDB", undefined);
        await queryRunner.query("ALTER TABLE `simple_example` ADD CONSTRAINT `FK_36c1bea209538ff07049dd748ad` FOREIGN KEY (`user_id`) REFERENCES `users2`(`id`) ON DELETE NO ACTION ON UPDATE NO ACTION", undefined);
    }

    public async down(queryRunner: QueryRunner): Promise<any> {
        await queryRunner.query("ALTER TABLE `simple_example` DROP FOREIGN KEY `FK_36c1bea209538ff07049dd748ad`", undefined);
        await queryRunner.query("DROP INDEX `REL_36c1bea209538ff07049dd748a` ON `simple_example`", undefined);
        await queryRunner.query("DROP INDEX `IDX_a1ebc46dd9a46cf638f43239fe` ON `simple_example`", undefined);
        await queryRunner.query("DROP TABLE `simple_example`", undefined);
        await queryRunner.query("DROP TABLE `users2`", undefined);
    }
}

Second migration with no changes to the model

import {MigrationInterface, QueryRunner} from "typeorm";

export class generateAfterNoChanges1574282199014 implements MigrationInterface {

    public async up(queryRunner: QueryRunner): Promise<any> {
        await queryRunner.query("ALTER TABLE `simple_example` DROP FOREIGN KEY `FK_36c1bea209538ff07049dd748ad`", undefined);
        await queryRunner.query("DROP INDEX `IDX_a1ebc46dd9a46cf638f43239fe` ON `simple_example`", undefined);
        await queryRunner.query("ALTER TABLE `simple_example` ADD UNIQUE INDEX `IDX_36c1bea209538ff07049dd748a` (`user_id`)", undefined);
        await queryRunner.query("CREATE UNIQUE INDEX `IDX_a1ebc46dd9a46cf638f43239fe` ON `simple_example` (`user_id`, `choice`)", undefined);
        await queryRunner.query("ALTER TABLE `simple_example` ADD CONSTRAINT `FK_36c1bea209538ff07049dd748ad` FOREIGN KEY (`user_id`) REFERENCES `users2`(`id`) ON DELETE NO ACTION ON UPDATE NO ACTION", undefined);
    }

    public async down(queryRunner: QueryRunner): Promise<any> {
        await queryRunner.query("ALTER TABLE `simple_example` DROP FOREIGN KEY `FK_36c1bea209538ff07049dd748ad`", undefined);
        await queryRunner.query("DROP INDEX `IDX_a1ebc46dd9a46cf638f43239fe` ON `simple_example`", undefined);
        await queryRunner.query("ALTER TABLE `simple_example` DROP INDEX `IDX_36c1bea209538ff07049dd748a`", undefined);
        await queryRunner.query("CREATE UNIQUE INDEX `IDX_a1ebc46dd9a46cf638f43239fe` ON `simple_example` (`user_id`, `choice`)", undefined);
        await queryRunner.query("ALTER TABLE `simple_example` ADD CONSTRAINT `FK_36c1bea209538ff07049dd748ad` FOREIGN KEY (`user_id`) REFERENCES `users2`(`id`) ON DELETE NO ACTION ON UPDATE NO ACTION", undefined);
    }
}

[noneedinmagic]

Try default: () => 'NULL' in column config.

@noneedinmagic Where would this need to go to fix the issue?

In column config. Like

@Column({
  name: 'optional_column',
  default: () => 'NULL',
})
optionalColumn: string;

[zorji]

I am still able to reproduce this issue in 0.3.4