Add option to generate all undefined as null or undefined.

[ryanelian]

We believe we have an issue when generating from Python to TypeScript.

For some reason, the API may return T | null but the type generated using openapi-typescript is T | undefined

Can we have an option to modify the output to allow both T | null | undefined?

[webmonch]

Running in the same issue

[alexanderchr]

Check your OpenAPI schema. Most likely your fields are marked as not required but not nullable. The generated TS types just reflect this by allowing undefined (since not required) but not null (since not nullable). In your case you'd want the fields to be required but nullable. Better to fix on the schema generating side... Annoying consequence of JS having both undefined and null.

[drwpow]

Could you give a reproduction of a schema you’re using, what’s being generated, and what you’d like to see instead? Without more information it’s impossible to know what’s happening here.

[ryanelian]

Check your OpenAPI schema. Most likely your fields are marked as not required but not nullable. The generated TS types just reflect this by allowing undefined (since not required) but not null (since not nullable). In your case you'd want the fields to be required but nullable. Better to fix on the schema generating side... Annoying consequence of JS having both undefined and null.

Could you give a reproduction of a schema you’re using, what’s being generated, and what you’d like to see instead? Without more information it’s impossible to know what’s happening here.

Thank you for the replies. Upon inspection, it appears that FastAPI returns invalid OpenAPI Schema.

• Snippet of JSON from an API response:

{
    "items": [...],
    "cursor": null
}

• The schema:

I will report this to the back-end team. In the meantime, I will ask the team to look out for more of these issues.

Please let me keep the thread open for now. Thank you.

[drwpow]

If the issue is with an invalid schema, then there’s nothing we can do on our end.

Please let me keep the thread open for now.

This ticket tracker tracks issues with the openapi-typescript library, not other libraries, nor issues you’re experiencing. I’m going to close this, but if you have a valid schema, and there’s a bug in openapi-typescript, you can open as many new tickets as you find bugs 🙂