Fix handling of nullable schemas

[mikebolt]

Changes

Allow all types except UNKNOWN to be nullable.
Fixes #1821 and #1940 .

This could be considered a breaking change. Whenever users are processing a request in a server or processing a response in the client, there could be a type error due to the unhandled null case. However, this is a good change because it helps TypeScript prevent bugs.

How to Review

The actual code changes are limited to the end of the transformSchemaObjectWithComposition function in schema-object.ts.

I have added a new test containing the schema in issue #1940 . You can check that this output looks good.

I have also changed the expected values in the various github and digitalocean .ts test files (although they were possibly overwritten by the update:examples script). Wherever I added | null to a type, its corresponding schema is nullable. This is something you can double-check, although there are a few hundred cases.

Checklist

• [ Yes ] Unit tests updated
• [ N/A ] docs/ updated (if necessary)
• [ Yes ] pnpm run update:examples run (only applicable for openapi-typescript)

[changeset-bot]

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Latest commit: 3a725fd

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[drwpow]

Thanks for adding this! While I agree—this may be breaking, I think it’s a sensible enough change, and people have asked for this, that I think it’s fine to introduce. Be sure to add a minor changeset patch so the version gets bumped! (see changeset comment)

The only change I’d request that we need tests for the “new” preferred syntax of oneOf: [SchemaFoo, { type: "null" }] (as opposed to the “old” syntax of nullable: true, which is still technically supported but discouraged). With those tests in there for this feature (you’ll see related tests like this), then I’d be happy to approve & ship.