Use new value from context when it is updated - Reactjs

RichardBarraclough
March 10, 2023
234 views
0 votes
2 Answers

I load my settings from the server:

import { Context, createContext, useEffect, useState } from "react";

export class AppSettings {
    buildName: string = '';
    authority: string = '';
    truthPortalApi: string = '';
    environment: string = '';
}

export const AppSettingsContext: Context<AppSettings> = createContext<AppSettings>(null!)

export const AppSettingsProvider: React.FC<{ children: JSX.Element }> = ({ children }) => {
    const [settings, setSettings] = useState<AppSettings>(new AppSettings())

    useEffect(() => {
        fetch(`${window.location.origin}/settings`)
            .then(response => response.json())
            .then(data => setSettings(data))
    }, []);

    return (
        <AppSettingsContext.Provider value={settings}>
            {children}
        </AppSettingsContext.Provider>
    )
}

and then I use them:

...
export const AuthContext: Context<AuthService> = createContext<AuthService>(null!);

export const AuthProvider: React.FC<{ children: JSX.Element[] }> = ({ children }) => {
    let appSettings: AppSettings = useContext<AppSettings>(AppSettingsContext)!;
    const [authService, setAuthService] = useState<AuthService>(new AuthService(appSettings));

    return (
        <AuthContext.Provider value={authService}>
        { children }
        </AuthContext.Provider>
    );
}

export function useAuth(): AuthService {
    return useContext(AuthContext);
}

However, something that uses auth via let auth: AuthService = useAuth(); only gets the inital emty value. It doesn’t get the real value after it’s loaded.
Can this work in React?

Tags: react-hooks reactjs

Answers

Chosen as BEST ANSWER

The package oidc-client-ts seems to be the least broken, but you have to wrap it like this in order to pass in the settings.

import { Fragment, useEffect, useState } from "react";

import { AuthContextProps, AuthProvider, hasAuthParams, useAuth } from 'react-oidc-context';
import { User, } from "oidc-client-ts";
import { AppSettings, useAppSettings } from "./appSettings";
import Loading from "./components/Loading/Loading";

import { NavigateFunction, useNavigate } from "react-router";

let url: string = `${window.location.origin}/`;

export const LocalAuthProvider: React.FC<{ children: JSX.Element | JSX.Element[] }> = ({ children }) => {
    let appSettings: null | AppSettings = useAppSettings();

    let [loading, setLoading] = useState<boolean>(true);

    useEffect(() => {
        setLoading((appSettings?.authority ?? '') === '');

    }, [appSettings]);

    // Copied from https://github.com/authts/react-oidc-context/blob/f175dcba6ab09871b027d6a2f2224a17712b67c5/src/AuthProvider.tsx#L20-L30
    let signinCallback = (_user: User | void): void => {
        window.history.replaceState(
            {},
            document.title,
            window.location.pathname
        )
    };

    return (
        <Loading loading={loading || (appSettings?.authority ?? '') === ''}>
            {loading || (appSettings?.authority ?? '') === '' ? (null) : (
                <AuthProvider //userManager={userManager} doesn't work, all other settings must be passed
                    authority={appSettings!.authority}
                    client_id={'truth_portal'}
                    redirect_uri={url}
                    silent_redirect_uri={`${url}silent-callback.html`}
                    post_logout_redirect_uri={url}
                    response_type={'code'}
                    scope={'openid profile offline_access truth_portal'}
                    loadUserInfo={true}
                    onSigninCallback={signinCallback}
                >
                    {children}
                </AuthProvider>
            )}
        </Loading>
    );
}

(Edit)

You are not updating the authService when appSettings change. This line only sets the initial value once (although it recreates a new AuthService on each render).

const [authService, setAuthService] = useState<AuthService>(new AuthService(appSettings));

You need a useEffect to create a new AuthService when appSettings change:

useEffect(() => {
  setAuthService(new AuthService(appSettings));
}, [appSettings]);

In addition, you should avoid creating redundant AuthService on each render by using lazy initial values function, which would only create the initial AuthService on mount:

const [authService, setAuthService] = useState<AuthService>(
  () => new AuthService(appSettings) // lazy initial value
);

Example:

export const AuthProvider: React.FC<{ children: JSX.Element[] }> = ({ children }) => {
    let appSettings: AppSettings = useContext<AppSettings>(AppSettingsContext)!;
    const [authService, setAuthService] = useState<AuthService>(
      () => new AuthService(appSettings) // lazy initial value
    );
    
    // update on mount and when appSettings change
    useEffect(() => {
      setAuthService(new AuthService(appSettings));
    }, [appSettings]);

    return (
        <AuthContext.Provider value={authService}>
        { children }
        </AuthContext.Provider>
    );
}

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Use new value from context when it is updated – Reactjs

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