Updated Offer to only change code once

no-issue

This simplifies the handling of updating redirects for a code, and
doesn't affect our application layer because we never have the need to
change a code twice.

In future this should be replaced with events at the domain level - so
that we do not have to track changed properties and instead a redirect
service can listen to events, which would be dispatched on a successful
save by the repository.

ghost/offers/index.js

@@ -20,10 +20,8 @@ class OffersModule {
      */
     async init() {
         DomainEvents.subscribe(OfferCodeChangeEvent, (event) => {
-            if (event.data.previousCodes) {
-                for (const previousCode of event.data.previousCodes) {
-                    this.redirectManager.removeRedirect(`/${previousCode.value}`);
-                }
+            if (event.data.previousCode) {
+                this.redirectManager.removeRedirect(`/${event.data.previousCode.value}`);
             }
             this.redirectManager.addRedirect(
                 `/${event.data.currentCode.value}`,

ghost/offers/lib/application/OfferRepository.js

@@ -131,7 +131,7 @@ class OfferRepository {
         if (offer.codeChanged || offer.isNew) {
             const event = OfferCodeChangeEvent.create({
                 offerId: offer.id,
-                previousCodes: offer.isNew ? null : offer.oldCodes,
+                previousCode: offer.oldCode,
                 currentCode: offer.code
             });
             DomainEvents.dispatch(event);

ghost/offers/lib/domain/events/OfferCodeChange.js

@@ -3,7 +3,7 @@
 /**
  * @typedef {object} OfferCodeChangeEventData
  * @prop {string} offerId
- * @prop {OfferCode[]} previousCodes
+ * @prop {OfferCode} previousCode
  * @prop {OfferCode} currentCode
  */
 

ghost/offers/lib/domain/models/Offer.js

@@ -117,12 +117,12 @@ class Offer {
         return this.props.duration;
     }
 
-    get oldCodes() {
+    get oldCode() {
         return this.changed.code;
     }
 
     get codeChanged() {
-        return this.changed.code.length > 0;
+        return this.changed.code !== null;
     }
 
     get displayTitle() {
@@ -174,12 +174,17 @@ class Offer {
         if (code.equals(this.props.code)) {
             return;
         }
+        if (this.changed.code) {
+            throw new errors.InvalidOfferCode({
+                message: 'Offer `code` cannot be updated more than once.'
+            });
+        }
         if (!await uniqueChecker.isUniqueCode(code)) {
             throw new errors.InvalidOfferCode({
                 message: 'Offer `code` must be unique.'
             });
         }
-        this.changed.code.push(this.props.code);
+        this.changed.code = this.props.code;
         this.props.code = code;
     }
 
@@ -197,7 +202,6 @@ class Offer {
                 message: 'Offer `name` must be unique.'
             });
         }
-        this.changed.name.push(this.props.name);
         this.props.name = name;
     }
 
@@ -214,8 +218,8 @@ class Offer {
         this.options = options;
         /** @private */
         this.changed = {
-            code: [],
-            name: []
+            /** @type OfferCode */
+            code: null
         };
     }