feat: Add HTTP endpoints and workflows for price preference management (#7960)

REF CORE-2376

Remaining pieces are adding UI to manage the flag, showing the flag in price editor, plugging it in cart calculations, and https://github.com/medusajs/medusa/pull/7827

packages/modules/pricing/src/joiner-config.ts

@@ -2,7 +2,7 @@ import { defineJoinerConfig, Modules } from "@medusajs/utils"
 import { Price, PriceList, PricePreference, PriceSet } from "@models"
 
 export const joinerConfig = defineJoinerConfig(Modules.PRICING, {
-  models: [PriceSet, PriceList, Price],
+  models: [PriceSet, PriceList, Price, PricePreference],
   linkableKeys: {
     price_set_id: PriceSet.name,
     price_list_id: PriceList.name,

packages/modules/pricing/src/services/pricing-module.ts

@@ -734,7 +734,10 @@ export default class PricingModuleService
       sharedContext
     )
 
-    return await this.baseRepository_.serialize<any[]>(preferences)
+    const serialized = await this.baseRepository_.serialize<
+      PricePreferenceDTO[]
+    >(preferences)
+    return Array.isArray(data) ? serialized : serialized[0]
   }
 
   async upsertPricePreferences(
@@ -800,11 +803,38 @@ export default class PricingModuleService
     data: PricingTypes.UpdatePricePreferenceDTO,
     @MedusaContext() sharedContext: Context = {}
   ): Promise<PricePreferenceDTO | PricePreferenceDTO[]> {
-    const preferences = await this.pricePreferenceService_.update(
-      data,
+    let normalizedInput: ServiceTypes.UpdatePricePreferenceInput[] = []
+    if (isString(idOrSelector)) {
+      // Check if the ID exists, it will throw if not.
+      await this.pricePreferenceService_.retrieve(
+        idOrSelector,
+        {},
+        sharedContext
+      )
+      normalizedInput = [{ id: idOrSelector, ...data }]
+    } else {
+      const pricePreferences = await this.pricePreferenceService_.list(
+        idOrSelector,
+        {},
+        sharedContext
+      )
+
+      normalizedInput = pricePreferences.map((pricePreference) => ({
+        id: pricePreference.id,
+        ...data,
+      }))
+    }
+
+    const updateResult = await this.pricePreferenceService_.update(
+      normalizedInput,
       sharedContext
     )
-    return await this.baseRepository_.serialize<any[]>(preferences)
+
+    const pricePreferences = await this.baseRepository_.serialize<
+      PricePreferenceDTO[] | PricePreferenceDTO
+    >(updateResult)
+
+    return isString(idOrSelector) ? pricePreferences[0] : pricePreferences
   }
 
   @InjectTransactionManager("baseRepository_")