Shopify Storefront API with Apollo Cache Management

Apollo Client's InMemoryCache stores entities such as Shopify Product and ProductVariant records by cache identity, allowing the same variant to be reused across queries. Stable GraphQL IDs and suitable typePolicies are important because a missing key can make one product appear as duplicate objects.

A successful Storefront API mutation does not automatically tell Apollo that every cached Product or ProductVariant price is obsolete. Use the returned fields, cache.modify, refetch, or a network-only policy when the application needs fresh data.

Handle the Storefront API response from a mutation such as cartLinesAdd, then write the returned cart and lines into the cache or refetch the cart query. Matching the cart ID and line IDs prevents Apollo from creating a second cached cart.

Duplicates usually appear when Apollo cannot identify the same Shopify Product, ProductVariant, or Cart consistently across responses. Inspect the GraphQL IDs and typePolicies, especially keyFields and pagination keyArgs, before adding manual cache writes.