Incorrect types when using optional property with nested structure and deep option

[monisnap-paul]

When using optional properties in a type and the option deep: true, the nested type is not properly converted to camelcase.

Here is a repository which reproduces the error.
https://github.com/monisnap-paul/camelcase-keys-bug

[sindresorhus]

// @g-plane

[g-plane]

This may be able to be fixed, but the "optional" mark will be lost as the given example. For example:

type Source = { a?: string }

will become:

type Result = { a: string | undefined }

These are different in TypeScript.

[monisnap-paul]

There are actually two issues with the given example:

1. "City" and "Country" properties in the type are not properly converted to camelcase
2. "?" is not equivalent to "| undefined"

[g-plane]

"?" is not equivalent to "| undefined"

I know, but we can't operate: TypeScript playground.

[salemhilal]

I wanted to bump this. It seems like even if { someKey?: string} is different than { someKey: string | undefined }, that's probably a level less important than having the type be { some_key?: string } but having the actual value be { someKey: string | undefined }.

If that's a cool assumption to make, I'd be open to submitting a patch for this issue.

[RichiCoder1]

Ironically I think this fix for this is to use the type CamelCasedPropertiesDeep from type-fest.

[jandolezal71]

I wanted to bump this. It seems like even if { someKey?: string} is different than { someKey: string | undefined }, that's probably a level less important than having the type be { some_key?: string } but having the actual value be { someKey: string | undefined }.

If that's a cool assumption to make, I'd be open to submitting a patch for this issue.

Output type should be { someKey?: string | undefined } or { someKey?: string }.

In some cases you don't want to pass keys with undefined values explicitely.