Using a custom text array type in postgres results in the migration generator to always include alter statements

[yanniz0r]

Hey folks!

At first: Thanks for this awesome library! I really like the developer experience and the code base is one of the cleanest in TS I've seen so far. 🎉

Describe the bug
Adding a custom type, in my case a StringArrayType which is basically the solution provided here, results in the migration creation to generate the "dirty" migration file. My type looks like this:

import { Type } from 'mikro-orm';

/**
 * This type used until version 4 of mikro orm is released as it supports array types natively
 */
class StringArrayType extends Type {
  convertToDatabaseValue(javascriptValue?: string[]) {
    const stringValues = javascriptValue?.map(value => JSON.stringify(value)).join(',');
    return `{${stringValues}}`;
  }
  toJSON(javascriptValue: string[]) {
    return JSON.stringify(javascriptValue);
  }
  convertToJSValue(databaseValue: string) {
    return databaseValue;
  }
  getColumnType(){
    return 'text[]';
  }
}

export default StringArrayType;

I found out, that the database returns a udt_name of _text which does neither match the provided type from getColumnType nor the types provided in the PostgreSqlSchemaHelper.TYPES. Adding textArray: ['_text', 'text[]'], to the TYPES object resolves the issue for me. If this solution is viable for mikro-orm I'm happy to provide a pull request - However, I think this is not the best solution.

To Reproduce
Steps to reproduce the behavior:

1. Add the custom type specified above as a type on an entity
2. Create an migration with yarn mikro-orm migration:create
3. Migrate the database with yarn mikro-orm migration:up
4. Create another migration with yarn mikro-orm migration:create

Observed behavior
The migration contains something like the following:

    this.addSql('alter table "events" drop constraint if exists "events_genres_check";');
    this.addSql('alter table "events" alter column "genres" type text[] using ("genres"::text[]);');

Even if you keep this, run the migration and create another one, a similar file is always created.
Expected behavior
The created migration should be empty as no changes have happend.

Versions

Dependency	Version
node	v14.4.0
typescript	3.9.6
mikro-orm	3.6.15
pg	8.3.0

[yanniz0r]

I just had a look at you solution for version 4. The problem is solved as follows: https://github.com/mikro-orm/mikro-orm/pull/559/files#diff-71ca1e86f35878d6b6b39e1b45e91a84R77

So my issue will probably be resolved with version 4. How is the current estimation for the release? Is there anything I can do to help?

[B4nan]

Ok, so closing this as resolved in v4 (I am not planning to ship more v3 releases).

How is the current estimation for the release?

Will be merging it during the weekend and releasing RC. Then probably week or two to adjust docs and write a release article, but in general its ready.

Is there anything I can do to help?

Migrate to v4 and test it :] I am using the latest alpha in my production app, working fine for me, so I'd say nothing to be afraid of, especially if you have your app covered with tests.