Typescript - keyof object as 'OR strings option'-CodePudding

I'm importing a .json file, and i want to get all the keys as optional parameters

import jsonFile from '../public/sample.json'

The json has unknown keys but, for the question, let's say it has the following:

{
  "greetings": {
    "hello": "Hello",
        "hello_informal": "Hi",
        "good_morning": "Good morning",
        "good_afternoon": "Good afternoon",
        "good_night": "Good night",
        "bye": "Bye"
  },
  "commons": {
    "pagination": {
            "first_page": "First page",
            "last_page": "Last page",
            "next_page": "Next page",
            "previous_page": "Previous page"
        }
  },
  "home": "Home sweet home"
}

And i have a function with 1 parameter.

function sample(keyValue: TypeKeyValue) {
  // logic here...
  console.log("Thank you Stackoverflow", keyValue)
}

My question is how create a type for that keyValue param for all the object keys (nested keys included, prefixed by parent keys with a dot). Value of the keys should not matter, just collect all the keys as optional.

i was trying this but is not working as expected:

type TypeKeyValue: keyof jsonFile

The desired result should be an automated way to get the following:

type TypeKeyValue: "greetings" | "greetings.hello" | "greetings.hello_informal" | "greetings.good_morning" | "greetings.good_afternoon" | "greetings.good_night" | "greetings | bye" | "commons" | "commons.pagination" | "commons.pagination.first_page" | "commons.pagination.last_page" | "commons.pagination.next_page" | "commons.pagination.previous_page" | "home"

Any help or solution would be much appreciated

CodePudding user response：

As long as you have the following options in your tsconfig.json typescript should automatically detect the type of imported JSON files:

"resolveJsonModule": true,
"esModuleInterop": true,

Afterwards you can get all keys of a JSON object in a type like this:

import jsonFile from '../public/sample.json'

type TypeKeyValue = keyof typeof jsonFile

If you also want all nested paths you will need to do something like this:

type Join<K, P> = K extends string | number ?
    P extends string | number ?
    `${K}${"" extends P ? "" : "."}${P}`
    : never : never;


type Prev = [never, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
    11, 12, 13, 14, 15, 16, 17, 18, 19, 20, ...0[]]

type Paths<T, D extends number = 10> = [D] extends [never] ? never : T extends object ?
    { [K in keyof T]-?: K extends string | number ?
        `${K}` | Join<K, Paths<T[K], Prev[D]>>
        : never
    }[keyof T] : ""

type Leaves<T, D extends number = 10> = [D] extends [never] ? never : T extends object ?
    { [K in keyof T]-?: Join<K, Leaves<T[K], Prev[D]>> }[keyof T] : "";

type Nested = Paths<typeof json>

In this case Nested will have all paths of the object.

CodePudding user response：

For a start you could use

type TypeKeyValue: keyof typeof jsonFile;

which will give you the root level keys.