CODEWITHSUNDEEP
typescripttypescript-typings
Eric Jansen
Eric Jansen

Reputation: 440

Typescript how to use type from package

I created an NPM package with a type defined (incl use):

(SolarEdge.js)

export type Period = 'DAY' | 'QUARTER_OF_AN_HOUR' | 'MONTH' | 'HOUR' | 'WEEK' | 'MONTH' | 'YEAR';
public getData = async (site: number, start: string, end: string, period: Period) => {}

(index.js)

export { default } from './SolarEdge';

After compiling from ts, I get 4 files (index.js, index.d.ts, SolarEdge.js, SolarEdge.d.ts)

When using this from my express app, it is complaining that I cant pass a string to this function, because it wants a Period.

Error: Argument of type 'string' is not assignable to parameter of type 'Period'.ts(2345)

Code:

    const data = await solaredge.getData(
        parseInt(req.params.site),
        req.params.start,
        req.params.end,
        //'MONTH',
        req.params.period,
    );

req.params.period contains a string with 'MONTH' or something else. WHen using the hardcoded string MONTH it works, but using the req.params.period variable, it doesnt.

I tried doing: req.params.period as Period but the problem is: it cant find Period.

How does this work?

Upvotes: 0

Views: 329

Answers (1)

jmellman
jmellman

Reputation: 466

TypeScript libraries that want to support TypeScript consumers must explicitly export their types as well as emit declaration files during compilation.

It looks like you're already doing this, so you should be able to explicitly import the Period type for use in your application code:

import { getData, Period }  from 'solaredge'

...

const data = await solaredge.getData(
    parseInt(req.params.site),
    req.params.start,
    req.params.end,
    //'MONTH',
    req.params.period as Period,
);

Upvotes: 1

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