B2C Custom Caches

Custom caches improve code performance by storing data that is expensive to calculate, takes a long time to retrieve, or is accessed frequently. Caches are defined in JSON files within cartridges and accessed via the Script API.

When to Use Custom Caches

Limitations

null

undefined

Defining a Custom Cache

File Structure

my_cartridge/
├── package.json       # References caches.json
└── caches.json        # Cache definitions

package.json

Add a

caches

{
  "name": "my_cartridge",
  "caches": "./caches.json"
}

caches.json

Define caches with unique IDs and optional expiration:

{
  "caches": [
    {
      "id": "ProductAttributeCache"
    },
    {
      "id": "ExternalPriceCache",
      "expireAfterSeconds": 300
    },
    {
      "id": "SiteConfigCache",
      "expireAfterSeconds": 60
    }
  ]
}

id

expireAfterSeconds

Using Custom Caches

Script API Classes

dw.system.CacheMgr

dw.system.Cache

Basic Usage

var CacheMgr = require('dw/system/CacheMgr');

// Get a defined cache
var cache = CacheMgr.getCache('ProductAttributeCache');

// Get value (returns undefined if not found)
var value = cache.get('myKey');

// Store value directly
cache.put('myKey', { data: 'value' });

// Remove entry
cache.invalidate('myKey');

Recommended Pattern: get with Loader

Use

get(key, loader)

var CacheMgr = require('dw/system/CacheMgr');
var Site = require('dw/system/Site');

var cache = CacheMgr.getCache('SiteConfigCache');

// Loader function called only on cache miss
var config = cache.get(Site.current.ID + '_config', function() {
    // Expensive operation - only runs if not cached
    return loadConfigurationFromFile(Site.current);
});

Scoped Cache Keys

Include scope identifiers in keys to separate entries by context:

var CacheMgr = require('dw/system/CacheMgr');
var Site = require('dw/system/Site');

var cache = CacheMgr.getCache('ProductCache');

// Site-scoped key
var siteKey = Site.current.ID + '_' + productID;
var productData = cache.get(siteKey, loadProductData);

// Catalog-scoped key
var catalogKey = 'catalog_' + catalogID + '_' + productID;
var catalogData = cache.get(catalogKey, loadCatalogData);

// Locale-scoped key
var localeKey = request.locale + '_' + contentID;
var content = cache.get(localeKey, loadLocalizedContent);

Cache Methods

get(key)

undefined

get(key, loader)

put(key, value)

invalidate(key)

Best Practices

Do

• Use

  get(key, loader)

  pattern for automatic population
• Include scope (site, catalog, locale) in cache keys
• Set appropriate

  expireAfterSeconds

  for time-sensitive data
• Handle cache misses gracefully (data may be evicted anytime)
• Use descriptive cache IDs

Don't

• Include personal user data in cache keys (keys may appear in logs)
• Store Script API objects (only primitives and plain objects)
• Rely on cache entries existing (no persistence guarantee)
• Expect cross-server cache synchronization
• Store

  undefined

  values (use

  null

  instead)

Cache Invalidation

Caches are automatically cleared when:

• Any file in the active code version changes
• A new code version is activated
• Data replication completes
• Code replication completes

Manual invalidation only affects the current application server:

var cache = CacheMgr.getCache('MyCache');

// Invalidate single entry (current app server only)
cache.invalidate('myKey');

// Storing undefined has same effect as invalidate
cache.put('myKey', undefined);

Common Patterns

Caching External API Responses

var CacheMgr = require('dw/system/CacheMgr');
var LocalServiceRegistry = require('dw/svc/LocalServiceRegistry');

var priceCache = CacheMgr.getCache('ExternalPriceCache');

function getExternalPrice(productID) {
    return priceCache.get('price_' + productID, function() {
        var service = LocalServiceRegistry.createService('PriceService', {
            createRequest: function(svc, args) {
                svc.setRequestMethod('GET');
                svc.addParam('productId', args.productID);
                return null;
            },
            parseResponse: function(svc, response) {
                return JSON.parse(response.text);
            }
        });

        var result = service.call({ productID: productID });
        return result.ok ? result.object : null;
    });
}

Caching Expensive Calculations

var CacheMgr = require('dw/system/CacheMgr');

var saleCache = CacheMgr.getCache('ProductSaleCache');

function isProductOnSale(masterProduct) {
    return saleCache.get('sale_' + masterProduct.ID, function() {
        var variants = masterProduct.variants.iterator();
        while (variants.hasNext()) {
            var variant = variants.next();
            if (isInPromotion(variant)) {
                return true;
            }
        }
        return false;
    });
}

Configuration Cache with Site Scope

var CacheMgr = require('dw/system/CacheMgr');
var Site = require('dw/system/Site');
var File = require('dw/io/File');
var FileReader = require('dw/io/FileReader');

var configCache = CacheMgr.getCache('SiteConfigCache');

function getSiteConfig() {
    var siteID = Site.current.ID;

    return configCache.get(siteID + '_config', function() {
        var configFile = new File(File.IMPEX + '/src/config/' + siteID + '.json');
        if (!configFile.exists()) {
            return null;
        }

        var reader = new FileReader(configFile);
        var content = reader.getString();
        reader.close();

        return JSON.parse(content);
    });
}

Troubleshooting

Check the custom error log and custom warn log for cache-related messages.