How to infer type of a nested object from app router output?

I have a tRPC router than returns a nested object through a db query. It looks like this:

ILessonCommentProps.comments: ({
    _count: {
        likes: number;
        comments: number;
        bookmarks: number;
    };
    comments: ({
        user: GetResult<{
            id: string;
            displayName: string | null;
            email: string | null;
            emailVerified: Date | null;
            ... 17 more ...;
            updatedAt: Date;
        }, unknown>;
        subComments: GetResult<...>[];
    } & GetResult<...>)[];
    bookmarks: {
        ...;
    }[];
    likes: {
        ...;
    }[];
} & GetResult<...>) | null

I'd like to infer the type of the comments property to use as an interface for props on a component. I tried doing this but this doesn't work:

interface ILessonCommentProps {
  comments: AppRouterOutputs['lessonBuilder']['getLessonLikesCommentsBookmarks']['comments'];
}

I was wondering if this is even possible?

type InnerType = OuterType['innerKey']

and for an array element

type InnerType = OuterType['innerKey'][number]

So it looks like you are on the right track, more info on the error you've facing might be helpful

It simply doesn't want to do that. It says comments is not a key in OuterType['innerKey']

If you do keyof what keys are returned?

You just need to investigate what the actual type is as you’re probably just navigating it wrong

Unions and intersections can make this more complicated though, it does look like a complex type