I am trying to integrate stripe on my SaaS. I have been stuck for the last 3 days trying to send unique userID metadata to stripe. my UUID doesn’t show on invoice.paid() hence i can’t tell which unique user has made the payment.

const db = admin.firestore();

module.exports = async (req, res) => {
  if (req.method === 'POST') {
    const { userId, priceId } = req.body;

    try {
      console.log('Creating session for Firebase UID:', userId);

      // Fetch the user from Firestore
      const userDoc = await db.collection('users').doc(userId).get();
      if (!userDoc.exists) {
        return res.status(404).json({ error: 'User not found' });
      }
      const userData = { uid: userDoc.id, ...userDoc.data() };

      // Create a checkout session
      const session = await stripe.checkout.sessions.create({
        payment_method_types: ['card'],
        line_items: [{ price: priceId, quantity: 1 }],
        mode: 'subscription',
        success_url: `${req.headers.origin}/success?session_id={CHECKOUT_SESSION_ID}`,
        cancel_url: `${req.headers.origin}/canceled`,
        client_reference_id: userId,
        customer_email: userData.email,
        metadata: { 
          firebaseUID: userId,
          userEmail: userData.email,
          subscriptionType: 'Pro'
        },
        subscription_data: {
          metadata: { 
            firebaseUID: userId,
            userEmail: userData.email,
            subscriptionType: 'Pro'
          }
        }
      });

      console.log('Checkout session created:', session.id);
      res.status(200).json({ sessionId: session.id });
    } catch (error) {
      console.error('Error creating checkout session:', error);
      res.status(500).json({ error: error.message });
    }
  } else {
    res.setHeader('Allow', 'POST');
    res.status(405).end('Method Not Allowed');
  }
};

It seems like I am sending the metadata to stripe, but it doesn’t show up on any of the stripe logs. Not sure what I am doing wrong. Would appreciate any advice/suggestion here.