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Tom Liang
Tom Liang

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Simple signup function using FP-TS

I tried to make a simple user signup function using FP-TS.

// user-controller.ts
import argon2 from "argon2";
import * as E from "fp-ts/Either";
import { flow, pipe } from "fp-ts/lib/function";
import * as TE from "fp-ts/TaskEither";
import {
    UserProfile,
    UserProfileRepository,
} from "../db/entities/user_profile";

function hashPassword(plainPassword: string) {
    return () => argon2.hash(plainPassword).then(E.right).catch(E.left);
}

export function signup(userName: string, email: string, password: string) {
    const makeUserProfile = (userPassword: string) =>
        new UserProfile({ userName, email, userPassword });
    return pipe(
        password,
        hashPassword,
        TE.chain(flow(makeUserProfile, UserProfileRepository.insertProfile))
    )();
}

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How to call:

// user-router.ts
import express from "express";
import { pipe } from "fp-ts/lib/function";
import { signup } from "../controllers/user-controller";
import * as E from "fp-ts/lib/Either";

router.post("/signup", async (req, res) => {
    const { username, password } = req.body;
    const userE = await signup(username, username, password);
    pipe(
        userE,
        E.bimap(
            (e) => res.send({ ok: false, message: e.message }),
            (user) =>
                res.send({
                    ok: true,
                    message: `user ${user.userName} registered `,
                })
        )
    );
});
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There must be better ways to compose the functions, will come back to it when I learn more.

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