Unstable custom type causes updates after find

[ladal1]

Describe the bug
We have custom type defined which works by parsing the value (for example equivalent operation is appending random number after string when saving to database (convertToDatabaseValue) and removing it in convertToJSValue function - so the two operations are not symmetrical, only in part of the output). However as the result of convertToDatabaseValue is random, it causes mikro orm to immediately update all hydrated entities as soon as .flush() is called, is it possible to

To Reproduce
Steps to reproduce the behavior:
Use type such as this: (define randint however you want)

export class SpecialStringType extends Type<string> {
  public convertToDatabaseValue(value?: string): string {
    return `${value}-{randint()}`
  }

  public convertToJSValue(value?: string): string {
    return value.split('-')[0]
  }

  public getColumnType(): string {
    return 'varchar';
  }

  public compareAsType(): string {
    return 'string';
  }
}

Use the type as a property and fetch such values.
Flush the EntityManager, you'll see updates for the fetched entities.

Expected behavior
Ability to set check on JS values, define custom comparator or simply not updating the first fetched values

Versions

Dependency	Version
node	18.17.1
typescript	5.2.2
mikro-orm	6.0.0-dev.91
your-driver	postgresql 6.0.0-dev.91

[B4nan]

Not sure if I understand the use case here, why would you have a random database value and stable runtime value? If you can describe the use case I can suggest some workarounds.

The change tracking works based on the database values, as that is what we know how to compare, as opposed to the runtime values which can be pretty much anything.

[B4nan]

Hmm the lerna diff check is apparently broken, I just removed it here so it will be out in few minutes.

https://github.com/mikro-orm/mikro-orm/actions/runs/6623912905

[ladal1]

Tested the release and it works just fine, however we can't use it yet, as it seems from our tests to have broken parsing of JSON fields when used in query builder. I'll try to figure out if It's something i can fix or expected change

[ladal1]

Ah, it's my old friend columnType vs type (first issue I found here 👍 ), rewriting definition of the property from { columnType: 'json', type: JsonType, nullable: true } to { type: 'json', nullable: true } fixed it

[B4nan]

That's weird, type: 'json' and type: JsonType should behave the same. Tried to reproduce in the tests but it seems to be working fine, so repro welcome for that.

[ladal1]

Tested it on our project, it seems it's not the type: JsonType which is causing the column to not serialize correctly but columnType: 'json'