Javascript

Building a Stripe App: A Step-by-Step Guide to QR Code Generation

Published Dec 18, 2024

Updated Dec 18, 2024

4 min read

Building a Stripe App: A Step-by-Step Guide to QR Code Generation

Why Build a Stripe App?

I recently participated in an audio space with the Stripe team, and something they said really stuck with me: the Stripe app store is a growing area that isn't overly saturated yet. There's a lot of potential for new apps, and companies can use this opportunity to grow.

I work at a company called This Dot Labs, and we've created several Stripe apps and even own one. After looking at the data, I can confirm that the Stripe team was right!

Creating a QR Code Generator App

For this tutorial, we'll build a QR code app that can take a URL and generate a code for it. This is a good use case to help you understand the ins and outs of Stripe's developer tools. stripeQRCode

Why QR Codes?

QR codes are useful tools that have become common in e-commerce, restaurants, and other industries. While Stripe already has a QR code tool, we'll make our own to familiarize ourselves with their syntax and problem-solving approaches.

Project Structure

Before we dive into the implementation, let's look at the structure of our Stripe App QR Code project:

.vscode: Contains settings for Visual Studio Code
source/views: Holds the main application views
.gitignore: Specifies files to ignore in version control
stripe-app.json: Defines the Stripe app configuration
ui-extensions.d.ts: TypeScript declaration file for UI extensions
.build: this is where the built Stripe app gets placed.

Step-by-Step Implementation

1. Install Stripe Locally

First, you need to install Stripe on your local machine. The documentation provides great instructions for this:

For Mac users: Use Brew to install
For Windows users: Download the package and add it to your environment variables

You can find the details here in the stripe docs to install the Stripe CLI https://docs.stripe.com/stripe-cli

When using Windows, you must do stripe login from Powershell, NOT from Git bash or any other tool. After the server is up, then you can continue using git bash for everything else. After stripe login, you need to enter stripe apps start. Once you do that, the server is up and running and you can go back to using git bash or any other tool.

2. Install Dependencies

We'll be using an extra package for QR code generation. Install it using npm:

npm install qrcode

3. Set Up the Main Component

Let's look at the home.tsx file, where we'll use Stripe's UI components:

import { Box, ContextView, Button, TextField, Banner } from 
'@stripe/ui-extension-sdk/ui';

These components are similar to other UI libraries like Bootstrap or Tailwind CSS.

4. Create the UI Structure

Our app will have:

An input field for the URL
Validation using a regex pattern
Error handling for invalid URLs
QR code generation and display

Here is the Home.tsx file that is located in the src/views folder image (86)

import {
  Box,
  ContextView,
  Button,
  TextField,
  Img,
  Banner,
} from "@stripe/ui-extension-sdk/ui";
import { useState } from 'react';
import QRCode from 'qrcode';
const Home = () => {
  const [url, setUrl] = useState('');
  const [qrCode, setQrCode] = useState('');
  const [error, setError] = useState('');
  const generateQRCode = async () => {
    try {
      if (!url) {
        setError("Please enter a URL.");
        return;
      }
//basic regex pattern for URL validation
      const urlPattern = new RegExp(
        '^(https?:\\/\\/)?' +
        '((([a-z\\d]([a-z\\d-]*[a-z\\d])*)\\.)+[a-z]{2,}|' +
        '((\\d{1,3}\\.){3}\\d{1,3}))' +
        '(\\:\\d+)?(\\/[-a-z\\d%_.~+]*)*' +
        '(\\?[;&a-z\\d%_.~+=-]*)?' +
        '(\\#[-a-z\\d_]*)?', 'i'
      );
      if (!urlPattern.test(url)) {
        setError("Please enter a valid URL (e.g., https://example.com)");
        return;
      }
      const qrCodeDataUrl = await QRCode.toDataURL(url, {
        width: 200,
        margin: 2,
      });
      setQrCode(qrCodeDataUrl);
      setError('');
    } catch (error) {
      console.error("Error generating QR code", error);
      setError("Failed to generate QR Code. Please try again.");
    }
  };
  return (
    <ContextView
      title="URL QR Code Generator"
      brandColor="#635bff"
      externalLink={{
        label: "Stripe Docs",
        href: "https://stripe.com/docs",
      }}
    >
      <Box css={{ stack: "y", rowGap: "large", padding: "medium" }}>
        <Box css={{ font: "heading", marginBottom: "medium" }}>
          Generate User Payment QR Code
        </Box>
        <TextField
          label="Enter URL"
          placeholder="https://example.com"
          value={url}
          onChange={(e) => setUrl(e.target.value)}
          type="url"
        />
        {error && (
          <Banner
            type="critical"
            title="Error"
            description={error}
          />
        )}
        <Button
          type="primary"
          onPress={() => generateQRCode()}
          disabled={!url}
        >
          Generate QR Code
        </Button>
        {qrCode && (
          <Box css={{
            stack: "y",
            rowGap: "medium",
            alignSelfY: "center",
            marginTop: "large"
          }}>
            <Box css={{ font: "heading" }}>Your QR Code</Box>
            <Img
              src={qrCode}
              alt="Generated QR Code"
            />
            <Button
              type="secondary"
              onPress={() => {
                window.open(qrCode, '_blank');
              }}
            >
              Download QR Code
            </Button>
          </Box>
        )}
      </Box>
    </ContextView>
  );
};
export default Home;

ContextView` is at the top level of the app where we see the Title and the link to the Stripe Docs that we placed in our Context View.
Box is how you use Divs.
Banners can be used to show notification errors or any other item you wish to display.
Textfields are input fields.
Everything else is pretty self-explanatory.

5. Handle Content Security Policy

One problem I personally ran into was when I tried to redirect users, the Stripe policies would block it since I did not express that I knew what it was doing. I had to go into the stripe-app.json file and mention the specific security policies. For this particular exercise, I kept these as null.

This is my stripe-app.json file.

{
    "id": "com.example.my-stripe-app",
    "version": "0.0.1",
    "name": "My Stripe App",
    "icon": "",
    "permissions": [],
    "stripe_api_access_type": "platform",
    "ui_extension": {
        "views": [
            {
                "viewport": "stripe.dashboard.home.overview",
                "component": "Home"
            },
            {
                "viewport": "stripe.dashboard.invoice.detail",
                "component": "Invoice"
            }
        ],
        "content_security_policy": {
            "connect-src": null,
            "image-src": null,
            "purpose": ""
        }
    }
}

6. Configure App Views

As you can see here, the stripe-app.json file shows the views for each file I have. The Home.tsx file and the Invoice.tsx are also included This is our way of saying that for each view we have, show the app functionality on that page. Our stripe-app.json file will show it but also, the manifest.js file in our .build folder will also show the same. Any view that doesn't have a file will not show the application's functionality. So, if I were to go to transactions, the app would not show the same logic as the home or invoices page.

By following these steps, you'll have a fully functional QR code generator app for Stripe. This is just a simple example, but the potential for Stripe apps is massive, especially for businesses serving e-commerce customers.

If you need help or get stuck, don't hesitate to reach out, danny.thompson@thisdot.co. The Stripe team is also very active in answering questions, so leverage them as a resource. Happy coding!

This Dot is a consultancy dedicated to guiding companies through their modernization and digital transformation journeys. Specializing in replatforming, modernizing, and launching new initiatives, we stand out by taking true ownership of your engineering projects.

We love helping teams with projects that have missed their deadlines or helping keep your strategic digital initiatives on course. Check out our case studies and our clients that trust us with their engineering.

About the author(s)

Danny Thompson

Introduction to Zod for Data Validation

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It's easy to start with simple schemas, and to add complexity as required. Zod provides different functions that represent data structures and related validation options, which can be combined to create larger schemas. In many cases, you'll probably be building a schema for a data object with properties of some primitive type. For example, here's a schema that would validate a JavaScript object representing an order for a pizza: ` Zod provides a number of primitives for defining schemas that line up with JavaScript primitives: string, number, bigint, boolean, date, symbol, undefined, and null. It also includes primitives void, any, unknown, and never for additional typing information. In addition to basic primitives, Zod can define object, array, and other native data structure schemas, as well as schemas for data structures not natively part of JavaScript like tuple and enum. The documentation contains considerable detail on the available data structures and how to use them. Parsing and Validating Data with Schemas With Zod schemas, you're not only telling your program what data should look like; you're also creating the tools to easily verify that the incoming data matches the schema definitions. This is where Zod really shines, as it greatly simplifies the process of validating data like user inputs or third party API responses. Let's say you're writing a website form to register new users. At a minimum, you'll need to make sure the new user's email address is a valid email address. For a password, we'll ask for something at least 8 characters long and including one letter, one number, and one special character. (Yes, this is not really the best way to write strong passwords; but for the sake of showing off how Zod works, we're going with it.) We'll also ask the user to confirm their password by typing it twice. First, let's create a Zod schema to model these inputs: ` So far, this schema is pretty basic. 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The main difference is that parse will throw an error if validation fails, while safeParse will return an object with a success property of either true or false, and either a data property with your parsed data or an error property with the details of a ZodError explaining why the parsing failed. In the case of our example data, userInput2 will parse just fine and return the data for you to use. But userInput1 will create a ZodError listing all of the ways it has failed validation. ` ` We can use these error messages to communicate to the user how they need to fix their form inputs if validation fails. Each error in the list describes the validation failure and gives us a human readable message to go with it. You'll notice that the validation errors for checking for a valid email and for checking password length have a lot of details, but we've got three items at the end of the error list that don't really tell us anything useful: just a custom error of Invalid input. 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Using z.infer<typeof YourSchema> will allow you to avoid writing extra TypeScript types that merely reflect the intent of your Zod schemas. You can create a type from any Zod schema like so: ` Using a TypeScript type derived from a Zod schema does *not* give you any extra level of data validation at the type level beyond what TypeScript is capable of. If you create a type from z.string.min(3).max(20), the TypeScript type will still just be string. And when compiled to JavaScript, even that will be gone! That's why you still need to use parse/safeParse on incoming data to validate it before proceeding as if it really does match your requirements. A common pattern with inferring types from Zod schemas is to use the same name for both. Because the schema is a variable, there's no name conflict if the type uses the same name. However, I find that this can lead to confusing situations when trying to import one or the other—my personal preference is to name the Zod schema with Schema at the end to make it clear which is which. Conclusion Zod is an excellent tool for easily and confidently asserting that the data you're working with is exactly the sort of data you were expecting. It gives us the ability to assert at runtime that we've got what we wanted, and allows us to then craft strategies to handle what happens if that data is wrong. Combined with the ability to infer TypeScript types from Zod schemas, it lets us write and run more reliable code with greater confidence....

Nov 15, 2024

7 mins

JavaScriptZod

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Building a Stripe App: A Step-by-Step Guide to QR Code Generation

Building a Stripe App: A Step-by-Step Guide to QR Code Generation

Why Build a Stripe App?

Creating a QR Code Generator App

Why QR Codes?

Project Structure

Step-by-Step Implementation

1. Install Stripe Locally

2. Install Dependencies

3. Set Up the Main Component

4. Create the UI Structure

5. Handle Content Security Policy

6. Configure App Views

Danny Thompson

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Introduction to Zod for Data Validation

Let's innovate together!

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Introduction to Zod for Data Validation