Updated typings

[zofiag]

Summary

Add missing sourceContentType and targetContentType in interface of transformEntriesToType params + enable undefined as a return value in deriveEntryForLocale.

Description

contentType: string; was replaced with

sourceContentType: string;
targetContentType: string;

undefined was added as accepted return value in deriveEntryForLocale.

deriveEntryForLocale: (
    inputFields: ContentFields,
    locale: string
  ) => { [field: string]: any } | undefined;

Motivation and Context

Make current functionalities consistent with the typings.

[chrislambe]

Not that I necessarily disagree with your styling changes, but it seems like a pretty sure way to get this PR rejected/ignored. I would love to see this change incorporated since the current interface is wildly incorrect compared to the docs. Maybe resubmit with only the meaningful changes?

Edit
It looks like the interface we want is defined right here:
https://github.com/contentful/contentful-migration/blob/f5b3595a862f03510b57d681aad7a53c96f3b33b/src/lib/interfaces/entry-transform-to-type.ts

Any reason we can't just use that instead of duplicating it?

[zofiag]

sorry for the automated formatting, is now gone. The linked interface TransformEntryToType could work if we also enable string as a return type from identityKey, so
identityKey: (fromFields: any) => Promise<string> | string. Then we could import that and reuse in index.d.ts for consistency reasons

[pappkamerad]

what is the status with that? we would also need correct typings.