How to pass access token and shop name to Shopify API Node new object

[The1987]

I posted on Stackoverflow and wanted to ask the community for help as well.

I am building a public shopify app and I want to add a POST route that allows a metafield to be created.

In the shopify-api-node module the following is stated:

accessToken - Required for public apps - A string representing the permanent OAuth 2.0 access token. This option is mutually exclusive with the apiKey and password options. If you are looking for a premade solution to obtain an access token, take a look at the shopify-token module."

Here is the object that needs the shopName and accessToken

const shopify = new Shopify({
                shopName: 'your-shop-name',
                accessToken: 'your-oauth-token' 
            });

In the Shopify Node / Express documentation it has you add in /shopify/callback route qwhich includes the the Oauth:

// Shopify Callback Route //
        app.get('/shopify/callback', (req, res) => {
            const { shop, hmac, code, state } = req.query;
            /// ... skipping over code ... ///
            request.post(accessTokenRequestUrl, { json: accessTokenPayload })
                .then((accessTokenResponse) => {
                    const accessToken = accessTokenResponse.access_token;
                    // DONE: Use access token to make API call to 'shop' endpoint
                    const shopRequestUrl = 'https://' + shop + '/admin/api/2019-04/shop.json';
                    const shopRequestHeaders = {
                        'X-Shopify-Access-Token': accessToken,
                    };

                });
             /// ... skipping over code ... ///
        });

Instead of using the shopify-token module can I access/should I access this information from the /shopify/callback route in the following manner (see below)? Or is there a better way to do this / can you provide examples?

Server.js

// Declare new global variables //
var accessTokenExport;
var shopExport;

// New Function //
 function exportTokens(accessToken) {
                accessTokenExport = accessToken;
                shopExport = shop;
            }

// Shopify Callback Route //
        app.get('/shopify/callback', (req, res) => {

        // Export variables to New Function
        exportTokens(shop, accessToken); 
        });

// New POST route //
 app.post("/api/createMetafield", function (req, res) {

                const shopify = new Shopify({
                    shopName: shopExport,
                    accessToken: accessTokenExport
                });

                shopify.metafield.create({
                    key: 'warehouse',
                    value: 25,
                    value_type: 'integer',
                    namespace: 'inventory',
                    owner_resource: 'metafield',
                    // owner_id: 632910392 
                }).then(
                    metafield => console.log(metafield),
                    err => console.error(err)
                );

            })

[Alex]

It looks like you were provided an answer that was flagged as accepted on stack overflow. Can you confirm that you have what you need now?

Cheers.

[The1987 · Accepted solution]

Yes, I received an answer. Thank you.