Added plan update option to stripe subscription update API (#154)

no issue

- Current update stripe subscription API calls only allowed cancelling a plan
- This change adds option to pass plan's nickname as `planName` in request to update subscription to new plan
- Checks if plan name is valid and updates stripe subscription to new plan at default prorate behavior

ghost/members-api/index.js

@@ -327,14 +327,15 @@ module.exports = function MembersApi({
     middleware.updateSubscription.use(ensureStripe, body.json(), async function (req, res) {
         const identity = req.body.identity;
         const cancelAtPeriodEnd = req.body.cancel_at_period_end;
+        const planName = req.body.planName;
         const subscriptionId = req.params.id;
 
         let member;
 
         try {
             if (!identity) {
                 throw new common.errors.BadRequestError({
-                    message: 'Cancel membership failed! Could not find member'
+                    message: 'Updating subscription failed! Could not find member'
                 });
             }
 
@@ -344,32 +345,44 @@ module.exports = function MembersApi({
 
             if (!member) {
                 throw new common.errors.BadRequestError({
-                    message: 'Cancel membership failed! Could not find member'
+                    message: 'Updating subscription failed! Could not find member'
                 });
             }
         } catch (err) {
             res.writeHead(401);
             return res.end('Unauthorized');
         }
-
         // Don't allow removing subscriptions that don't belong to the member
+        const plan = planName && stripe.findPlanByNickname(planName);
+        if (planName && !plan) {
+            throw new common.errors.BadRequestError({
+                message: 'Updating subscription failed! Could not find plan'
+            });
+        }
         const subscription = member.stripe.subscriptions.find(sub => sub.id === subscriptionId);
-
         if (!subscription) {
             res.writeHead(403);
             return res.end('No permission');
         }
 
-        if (cancelAtPeriodEnd === undefined) {
+        if (cancelAtPeriodEnd === undefined && planName === undefined) {
             throw new common.errors.BadRequestError({
-                message: 'Canceling membership failed!',
-                help: 'Request should contain boolean "cancel" field.'
+                message: 'Updating subscription failed!',
+                help: 'Request should contain "cancel" or "plan" field.'
             });
         }
+        const subscriptionUpdate = {
+            id: subscription.id
+        };
+        if (cancelAtPeriodEnd !== undefined) {
+            subscriptionUpdate.cancel_at_period_end = !!(cancelAtPeriodEnd);
+        }
 
-        subscription.cancel_at_period_end = !!(cancelAtPeriodEnd);
+        if (plan) {
+            subscriptionUpdate.plan = plan.id;
+        }
 
-        await stripe.updateSubscriptionFromClient(subscription);
+        await stripe.updateSubscriptionFromClient(subscriptionUpdate);
 
         res.writeHead(204);
         res.end();

ghost/members-api/lib/stripe/index.js

@@ -1,4 +1,5 @@
 const debug = require('ghost-ignition').debug('stripe');
+const _ = require('lodash');
 const {retrieve, list, create, update, del} = require('./api/stripeRequests');
 const api = require('./api');
 
@@ -187,14 +188,20 @@ module.exports = class StripePaymentProcessor {
     }
 
     async updateSubscriptionFromClient(subscription) {
-        const updatedSubscription = await update(this._stripe, 'subscriptions', subscription.id, {
-            cancel_at_period_end: subscription.cancel_at_period_end
-        });
+        const updatedSubscription = await update(
+            this._stripe, 'subscriptions',
+            subscription.id,
+            _.pick(subscription, ['plan', 'cancel_at_period_end'])
+        );
         await this._updateSubscription(updatedSubscription);
 
         return updatedSubscription;
     }
 
+    findPlanByNickname(nickname) {
+        return this._plans.find(plan => plan.nickname === nickname);
+    }
+
     async getSubscriptions(member) {
         const metadata = await this.storage.get(member);