feat(api): add listing search caching and apply @Cacheable decorator

- Add Redis caching to SearchListingsHandler (2 min TTL, query-based key)
- Refactor GetDistrictStatsHandler to use @Cacheable decorator
- Update search-listings test to provide mock CacheService

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/modules/analytics/application/queries/get-district-stats/get-district-stats.handler.ts

@@ -1,6 +1,6 @@
 import { Inject } from '@nestjs/common';
 import { QueryHandler, type IQueryHandler } from '@nestjs/cqrs';
-import { CacheService, CachePrefix, CacheTTL } from '@modules/shared';
+import { CacheService, CachePrefix, CacheTTL, Cacheable } from '@modules/shared';
 import {
   MARKET_INDEX_REPOSITORY,
   type IMarketIndexRepository,
@@ -18,20 +18,20 @@ export interface DistrictStatsDto {
 export class GetDistrictStatsHandler implements IQueryHandler<GetDistrictStatsQuery> {
   constructor(
     @Inject(MARKET_INDEX_REPOSITORY) private readonly marketIndexRepo: IMarketIndexRepository,
-    private readonly cache: CacheService,
+    private readonly cacheService: CacheService,
   ) {}
 
+  @Cacheable({
+    prefix: CachePrefix.MARKET_DISTRICT,
+    ttl: CacheTTL.DISTRICT_STATS,
+    resource: 'district_stats',
+    keyFrom: (query: unknown) => {
+      const q = query as GetDistrictStatsQuery;
+      return [q.city, q.period];
+    },
+  })
   async execute(query: GetDistrictStatsQuery): Promise<DistrictStatsDto> {
-    const cacheKey = CacheService.buildKey(CachePrefix.MARKET_DISTRICT, query.city, query.period);
-
-    return this.cache.getOrSet(
-      cacheKey,
-      async () => {
-        const districts = await this.marketIndexRepo.getDistrictStats(query.city, query.period);
-        return { city: query.city, period: query.period, districts };
-      },
-      CacheTTL.DISTRICT_STATS,
-      'district_stats',
-    );
+    const districts = await this.marketIndexRepo.getDistrictStats(query.city, query.period);
+    return { city: query.city, period: query.period, districts };
   }
 }

apps/api/src/modules/listings/application/__tests__/search-listings.handler.spec.ts

@@ -1,10 +1,12 @@
 import { type IListingRepository } from '@modules/listings/domain/repositories/listing.repository';
+import { type CacheService } from '@modules/shared';
 import { SearchListingsHandler } from '../queries/search-listings/search-listings.handler';
 import { SearchListingsQuery } from '../queries/search-listings/search-listings.query';
 
 describe('SearchListingsHandler', () => {
   let handler: SearchListingsHandler;
   let mockListingRepo: { [K in keyof IListingRepository]: ReturnType<typeof vi.fn> };
+  let mockCacheService: { [K in keyof CacheService]: ReturnType<typeof vi.fn> };
 
   beforeEach(() => {
     mockListingRepo = {
@@ -17,7 +19,14 @@ describe('SearchListingsHandler', () => {
       findBySellerId: vi.fn(),
     };
 
-    handler = new SearchListingsHandler(mockListingRepo as any);
+    mockCacheService = {
+      getOrSet: vi.fn((_key, loader) => loader()),
+      invalidate: vi.fn(),
+      invalidateByPrefix: vi.fn(),
+      onModuleInit: vi.fn(),
+    };
+
+    handler = new SearchListingsHandler(mockListingRepo as any, mockCacheService as any);
   });
 
   it('searches with all filters', async () => {

apps/api/src/modules/listings/application/queries/search-listings/search-listings.handler.ts

@@ -1,5 +1,6 @@
 import { Inject } from '@nestjs/common';
 import { QueryHandler, type IQueryHandler } from '@nestjs/cqrs';
+import { CacheService, CachePrefix, CacheTTL } from '@modules/shared';
 import { type ListingSearchItem } from '../../../domain/repositories/listing-read.dto';
 import { LISTING_REPOSITORY, type IListingRepository, type PaginatedResult } from '../../../domain/repositories/listing.repository';
 import { SearchListingsQuery } from './search-listings.query';
@@ -8,22 +9,45 @@ import { SearchListingsQuery } from './search-listings.query';
 export class SearchListingsHandler implements IQueryHandler<SearchListingsQuery> {
   constructor(
     @Inject(LISTING_REPOSITORY) private readonly listingRepo: IListingRepository,
+    private readonly cacheService: CacheService,
   ) {}
 
   async execute(query: SearchListingsQuery): Promise<PaginatedResult<ListingSearchItem>> {
-    return this.listingRepo.search({
-      status: query.status,
-      transactionType: query.transactionType,
-      propertyType: query.propertyType,
-      city: query.city,
-      district: query.district,
-      minPrice: query.minPrice,
-      maxPrice: query.maxPrice,
-      minArea: query.minArea,
-      maxArea: query.maxArea,
-      bedrooms: query.bedrooms,
-      page: query.page,
-      limit: query.limit,
-    });
+    const cacheKey = CacheService.buildKey(
+      CachePrefix.SEARCH,
+      query.status,
+      query.transactionType,
+      query.propertyType,
+      query.city,
+      query.district,
+      query.minPrice?.toString(),
+      query.maxPrice?.toString(),
+      query.minArea?.toString(),
+      query.maxArea?.toString(),
+      query.bedrooms?.toString(),
+      String(query.page),
+      String(query.limit),
+    );
+
+    return this.cacheService.getOrSet(
+      cacheKey,
+      async () =>
+        this.listingRepo.search({
+          status: query.status,
+          transactionType: query.transactionType,
+          propertyType: query.propertyType,
+          city: query.city,
+          district: query.district,
+          minPrice: query.minPrice,
+          maxPrice: query.maxPrice,
+          minArea: query.minArea,
+          maxArea: query.maxArea,
+          bedrooms: query.bedrooms,
+          page: query.page,
+          limit: query.limit,
+        }),
+      CacheTTL.SEARCH_RESULTS,
+      'listing_search',
+    );
   }
 }