Fetch Policies

A request's FetchPolicy determines how it is resolved by Ferry, either from the gql_link, from the Cache, or both.

For example, executing the following reviewsReq will bypass the cache and return results only from the network.

final reviewsReq = GAllPokemonReq(
(b) => b
..fetchPolicy = FetchPolicy.NetworkOnly
..vars.first = 10
..vars.offset = 0,
);

Valid options for FetchPolicy include:

  1. CacheFirst: Return result from cache. Only fetch from network if cached result is not available.
  2. CacheAndNetwork: Return result from cache first (if it exists), then return network result once it's available.
  3. NetworkOnly: Return result from network, fail if network call doesn't succeed, save to cache.
  4. CacheOnly: Return result from cache.
  5. NoCache: Return result from network, fail if network call doesn't succeed, don't save to cache

Default FetchPolicies

Ferry uses the following defaults for each GraphQL operation type:

  1. Query: CacheFirst
  2. Mutation: NetworkOnly
  3. Subscription: CacheAndNetwork

You can override these defaults by including a defaultFetchPolicies map when initializing the client.

import 'package:ferry/ferry.dart';
import 'package:gql/ast.dart';
final client = Client(
link: MyLink(),
defaultFetchPolicies: {
OperationType.query: FetchPolicy.CacheAndNetwork,
},
);