createSetupIntent

The createSetupIntent Firebase Cloud Function generates a Stripe SetupIntent. This is a crucial step for securely collecting and saving customer payment method details for future use, without immediately charging them. It’s typically used when a user wants to add a new payment method to their subscription.

Function Signature

export const createSetupIntent = https.onCall(async (data: CreateSetupIntentData, context) => { ... });

Parameters

The function expects the following data in the data object:

CreateSetupIntentData Interface:

interface CreateSetupIntentData {
    subscriptionId: string;
}

Context

The function requires an authenticated user context (context.auth). The authenticated user must also be the owner of the specified subscription.

Behavior

1. Authentication Check: Verifies that the user calling the function is authenticated. If not, it throws an unauthenticated error.
2. Subscription Retrieval: Fetches the subscription document from Firestore using the provided subscriptionId.
   • If the subscription does not exist, it throws a not-found error.
3. Owner Verification: Checks if the authenticated user is the owner (owner_id) of the subscription. If not, it throws a permission-denied error.
4. Stripe Customer ID Retrieval: Retrieves the Stripe subscription to get the associated customer ID.
   • If no customer is found for the subscription, it throws a failed-precondition error.
5. SetupIntent Creation: Calls the Stripe API to create a new SetupIntent for the retrieved customer, specifying card as the payment method type.
6. Success: Returns { success: true, clientSecret: string } containing the client_secret of the created SetupIntent. This client_secret is then used on the client-side to confirm the SetupIntent and collect payment details.

Error Handling

The function throws HttpsError with specific codes for different failure scenarios:

• unauthenticated: If the user is not authenticated.
• not-found: If the subscription is not found.
• permission-denied: If the user is not the subscription owner.
• failed-precondition: If no Stripe customer is associated with the subscription.
• internal: For any Stripe API errors or other unexpected errors during execution.

Example Usage (Client-side)

import { getFunctions, httpsCallable } from 'firebase/functions';
import { getApp } from 'firebase/app';
import { loadStripe } from '@stripe/stripe-js';

const functions = getFunctions(getApp());
const createSetupIntentCallable = httpsCallable(functions, 'createSetupIntent');

async function callCreateSetupIntent(subscriptionId: string) {
    try {
        const result = await createSetupIntentCallable({ subscriptionId });
        const { clientSecret } = result.data as { clientSecret: string };
        console.log('Setup Intent client secret:', clientSecret);

        // Example of using the client secret with Stripe.js on the client-side
        // const stripe = await loadStripe('YOUR_STRIPE_PUBLISHABLE_KEY');
        // if (stripe) {
        //     const { setupIntent, error } = await stripe.confirmCardSetup(clientSecret, {
        //         payment_method: {
        //             card: cardElement, // Your Stripe Elements Card Element
        //             billing_details: {
        //                 name: 'John Doe',
        //                 email: 'john.doe@example.com',
        //             },
        //         },
        //     });
        //     if (error) {
        //         console.error('Stripe SetupIntent confirmation error:', error);
        //     } else {
        //         console.log('SetupIntent succeeded:', setupIntent);
        //     }
        // }
        return clientSecret;
    } catch (error) {
        console.error('Error creating setup intent:', error.code, error.message);
        throw error;
    }
}

// Example call
// callCreateSetupIntent('sub_your_stripe_subscription_id');