Tech Tips: RedisJSON

Summary

I cover a shopping cart application use case in this post. I implement a full CRUD set for the users, products, and carts using the RedisJSON module.

Architecture

The Server-side is implemented as an Express.js app with the node-redis module. The test client is also Node-based with node-fetch used for the HTTP client and a random data generator I concocted with the uniqueNamesGenerator module.

Code Snippets

Random Data Generation

    static generateUser() {
        return {
            "userID": uuidv4(),
            "lastName":  RandomData.#getLastName(),
            "firstName": RandomData.#getFirstName(),
            "street": RandomData.#getStreet(),
            "city": RandomData.#getCity(),
            "state": RandomData.#getState(),
            "zip": RandomData.#getZip()    
        };
    };
    
    static #getFirstName() {
        return uniqueNamesGenerator({
            dictionaries:[names],
            length: 1
        });
    };

    static #getLastName() {
        return uniqueNamesGenerator({
            dictionaries: [adjectives],
            length: 1,
            style: 'capital'
        });
    };

Create User - Client-side

async function createUser(dbType, user) {
    const response = await fetch(`${SERVER.url}/${dbType}/user`, {
        method: 'POST',
        body: JSON.stringify(user),
        headers: {
            'Content-Type': 'application/json',
            'Authorization': AUTH
        }
    });
    return await response.json();
};

const user = RandomData.generateUser();
res = await createUser('redis', user);

Update Cart - Server-side

app.patch('/:dbType/cart/:cartID', async (req, res) => {
    switch (req.params.dbType) {
        case 'redis':
            try {
                var client = await redisConnect();
                const updatedItem = req.body;
                const items = await client.json.get(`cart:${req.params.cartID}`, {path:'.items'}); 
                const newItems = [];
                let found = false
                for (let item of items) {
                    if (updatedItem.sku == item.sku) {
                        found = true;
                        if (updatedItem.quantity == 0) {
                            continue;
                        }
                        else {
                            newItems.push(updatedItem)
                        }
                        break;
                    }
                    else {
                        newItems.push(item);
                    }
                }
                if (!found) {
                    newItems.push(updatedItem)
                }           
                const val = await client.json.set(`cart:${req.params.cartID}`, `.items`, newItems);

                if (val == 'OK') {
                    console.log(`200: Cart ${req.params.cartID} updated`);
                    res.status(200).json({'cartID': req.params.cartID});
                }
                else {
                    throw new Error(`Cart ${req.params.sku} not fully updated`);
                }
            }
            catch (err) {
                console.error(`400: ${err.message}`);
                res.status(400).json({error: err.message});
            }
            finally {
                await client.quit();
            };
            break;
        default:
            const msg = 'Unknown DB Type';
            console.error(`400: ${msg}`);
            res.status(400).json({error: msg});
            break;
    };
});

Source

https://github.com/joeywhelan/redisJSON

Tech Tips

Monday, May 30, 2022

RedisJSON - CRUD Ops