Question

78

Read strongly typed yaml file in Typescript?

rated 0 times [ 83] [ 5] / answers: 1 / hits: 18808 / 3 Years ago, wed, june 23, 2021, 12:00:00

I have the following yaml file:

trainingPhrases:

- help me

- what to do

- how to play

- help

I readi it from disk using readFile from node and parse it using load from js-yaml:

import { load } from "js-yaml";

import { readFile } from "fs/promises";



const phrases = load(await readFile(filepath, "utf8")).trainingPhrases as string[];

I get the following eslint warning:

ESLint: Unsafe member access .trainingPhrases on an any value.(@typescript-eslint/no-unsafe-member-access)

Instead of suppressing the warning, I would like to map it into a concrete type for the YAML file (as it happens in axios for example: axios.get<MyResponseInterface>(...) - performs a GET and MyResponseInterface defines the structure of the HTTP response).

Is there a dedicated library for that?

Answers

Only authorized users can answer the question. Please sign in first, or register a free account.

kennedysaraiw

Add To Favorites

Follow

Total Points: 552

Total Questions: 99

Total Answers: 109

Location: South Sudan

Member since Sun, Jul 11, 2021

3 Years ago

answered 3 Years ago trayvon · Accepted Answer

From what I can see when using @types/js-yaml is that load is not generic, meaning it does not accept a type parameter.

So the only way to get a type here is to use an assertion, for example:

const yaml = load(await readFile(filepath, "utf8")) as YourType;

const phrases = yaml.trainingPhrases;

Or in short:

const phrases = (load(await readFile(filepath, "utf8")) as YourType).trainingPhrases;

If you absolutely want a generic function, you can easily wrap the original, like:

import {load as original} from 'js-yaml';



export const load = <T = ReturnType<typeof original>>(...args: Parameters<typeof original>): T => load(...args);

And then you can use it as:

const phrases = load<YourType>('....').trainingPhrases;