TypeScript - How can pick off some properties from a interface in TypeScript?

Question

e.g. I defined a structure for posts like this:

interface PostsInfo{
    md_content    :string;
    id            :number;
    title         :string;
    description   :string;
    update_time   :Date;
    create_time   :Date;
    comment_count :number;
}

then, I need an other interface that without a property which is md_content.

interface PostsInfoWithoutContent{
    // How define?
}

It can fix this right now that make PostsInfo extend PostsInfoWithoutContent, but, if I do like that, how can I do when I need PostsInfoWithoutComment (remove comment_count from PostsInfo)?

Answer 1

You can use the buit-in Pick type to get part of an interface :

type PostsInfoWithoutConent= Pick<PostsInfo, "id" | "title">

If you just want to exclude one property you might be better off defining the the Omit type and use that

type Diff<T extends string, U extends string> = ({[P in T]: P } & {[P in U]: never } & { [x: string]: never })[T];  
type Omit<T, K extends keyof T> = Pick<T, Diff<keyof T, K>>; 
type PostsInfoWithoutContent= Omit<PostsInfo, "md_content">