Transformer order is inconsistent

[jbdemonte]

The execution order of the transformers should always be the same.
It seems to be reverse each time it's used

    class TestDto {
      @Expose()
      @Transform(() => console.log('A'), { toClassOnly: true })
      @Transform(() => console.log('B'), { toClassOnly: true })
      @Transform(() => console.log('C'), { toClassOnly: true })
      value: string;
    }

    for (let i = 0; i < 4; i++) {
      console.log(`--- Loop ${i} ----`);
      plainToClass(TestDto, {});
    }

This test log:

--- Loop 0 ----
A
B
C
--- Loop 1 ----
C
B
A
--- Loop 2 ----
A
B
C
--- Loop 3 ----
C
B
A

[VinceOPS]

This is probably due to:

return (metadataFromAncestorsTarget).reverse().concat((metadataFromTarget || []).reverse());

in MetadataStorage#findMetadatas, called by MetadataStorage#findTransformMetadatas.

And is indeed a bug.

@247GradLabs any clue regarding the reason of these calls to reverse? Thanks a lot!

[alexpls]

@VinceOPS Indeed. I think the order should be reversed so the transformers get applied in the correct order, but since Array.prototype.reverse() mutates the array it's called on, every time that code is run the array switches ordering.

I'd be happy to work on a PR to fix this, once this package is under active maintenance again.

[kirit0s]

This bug made my day. Apparently, this bug is not critical for open source.

[github-actions]

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