Note: As of 3.0.0, Apollo Client uses a new package name: @apollo/client

Improvements

• [BREAKING] InMemoryCache will no longer merge the fields of written objects unless the objects are known to have the same identity, and the values of fields with the same name will not be recursively merged unless a custom merge function is defined by a field policy for that field, within a type policy associated with the __typename of the parent object.
• @benjamn in #5603
• [BREAKING] Eliminate “generated” cache IDs to avoid normalizing objects with no meaningful ID, significantly reducing cache memory usage. This is a backwards-incompatible change if your code depends on the precise internal representation of normalized data in the cache.
• @benjamn in #5146
• [BREAKING] Removed graphql-anywhere since it’s no longer used by Apollo Client.
• @hwillson in #5159
• [BREAKING] Removed apollo-boost since Apollo Client 3.0 provides a boost like getting started experience out of the box.
• @hwillson in #5217
• [BREAKING] The queryManager property of ApolloClient instances is now marked as private, paving the way for a more aggressive redesign of its API.
• [BREAKING] FragmentMatcher, HeuristicFragmentMatcher, and IntrospectionFragmentMatcher have all been removed. We now recommend using InMemoryCache’s possibleTypes option instead. For more information see the Defining [possibleTypes](https://www.apollographql.com/docs/react/v3.0-beta/data/fragments/#defining-possibletypes-manually) manually section of the docs.
• @benjamn in #5073
• [BREAKING] As promised in the Apollo Client 2.6 blog post, all cache results are now frozen/immutable.
• @benjamn in #5153
• [BREAKING] ApolloClient is now only available as a named export. The default ApolloClient export has been removed.
• @hwillson in #5425
• [BREAKING] The QueryOptions, MutationOptions, and SubscriptionOptions React Apollo interfaces have been renamed to QueryDataOptions, MutationDataOptions, and SubscriptionDataOptions (to avoid conflicting with similarly named and exported Apollo Client interfaces).
• [BREAKING] We are no longer exporting certain (intended to be) internal utilities. If you are depending on some of the lesser known exports from apollo-cache, apollo-cache-inmemory, or apollo-utilities, they may no longer be available from @apollo/client.
• @hwillson in #5437 and #5514
• [BREAKING?] Remove fixPolyfills.ts, except when bundling for React Native. If you have trouble with Map or Set operations due to frozen key objects in React Native, either update React Native to version 0.59.0 (or 0.61.x, if possible) or investigate why fixPolyfills.native.js is not included in your bundle.
• @benjamn in #5962
• [BREAKING] Apollo Client 2.x allowed @client fields to be passed into the link chain if resolvers were not set in the constructor. This allowed @client fields to be passed into Links like apollo-link-state. Apollo Client 3 enforces that @client fields are local only, meaning they are no longer passed into the link chain, under any circumstances.
• @hwillson in #5982
• [BREAKING] InMemoryCache now throws when data with missing or undefined query fields is written into the cache, rather than just warning in development.
• @benjamn in #6055
• [BREAKING] client|cache.writeData have been fully removed. writeData usage is one of the easiest ways to turn faulty assumptions about how the cache represents data internally, into cache inconsistency and corruption. client|cache.writeQuery, client|cache.writeFragment, and/or cache.modify can be used to update the cache.
• @benjamn in #5923
• [BREAKING] Apollo Client will no longer deliver “stale” results to ObservableQuery consumers, but will instead log more helpful errors about which cache fields were missing.
• @benjamn in #6058
• [BREAKING] ApolloError’s thrown by Apollo Client no longer prefix error messages with GraphQL error: or Network error:. To differentiate between GraphQL/network errors, refer to ApolloError’s public graphQLErrors and networkError properties.
• @lorensr in #3892
• [BREAKING] Support for the @live directive has been removed, but might be restored in the future if a more thorough implementation is proposed.
• @benjamn in #6221
• [BREAKING?] Refactor QueryManager to make better use of observables and enforce fetchPolicy more reliably.
• @benjamn in #6221
• InMemoryCache now supports tracing garbage collection and eviction. Note that the signature of the evict method has been simplified in a potentially backwards-incompatible way.
• @benjamn in #5310
• [beta-BREAKING] Please note that the cache.evict method now requires Cache.EvictOptions, though it previously supported positional arguments as well.
• @danReynolds in #6141 @benjamn in #6364
• Cache methods that would normally trigger a broadcast, like cache.evict, cache.writeQuery, and cache.writeFragment, can now be called with a named options object, which supports a broadcast: boolean property that can be used to silence the broadcast, for situations where you want to update the cache multiple times without triggering a broadcast each time.
• @benjamn in #6288
• InMemoryCache now console.warns in development whenever non-normalized data is dangerously overwritten, with helpful links to documentation about normalization and custom merge functions.
• @benjamn in #6372
• The contents of the @apollo/react-hooks package have been merged into @apollo/client, enabling the following all-in-one import:

import { ApolloClient, ApolloProvider, useQuery } from '@apollo/client';

• @hwillson in #5357
• Apollo Link core and HTTP related functionality has been merged into @apollo/client. Functionality that was previously available through the apollo-link, apollo-link-http-common and apollo-link-http packages is now directly available from @apollo/client (e.g. import { HttpLink } from '@apollo/client'). The ApolloClient constructor has also been updated to accept new uri, headers and credentials options. If uri is specified, Apollo Client will take care of creating the necessary HttpLink behind the scenes.
• @hwillson in #5412
• The gql template tag should now be imported from the @apollo/client package, rather than the graphql-tag package. Although the graphql-tag package still works for now, future versions of @apollo/client may change the implementation details of gql without a major version bump.
• @hwillson in #5451
• @apollo/client/core can be used to import the Apollo Client core, which includes everything the main @apollo/client package does, except for all React related functionality.
• @kamilkisiela in #5541
• @apollo/client/cache can be used to import the Apollo Client cache without importing other parts of the Apollo Client codebase.
• @hwillson in #5577
• The result caching system (introduced in #3394) now tracks dependencies at the field level, rather than at the level of whole entity objects, allowing the cache to return identical (===) results much more often than before.
• @benjamn in #5617
• InMemoryCache now has a method called modify which can be used to update the value of a specific field within a specific entity object:

cache.modify({
  id: cache.identify(post),
  fields: {
    comments(comments: Reference[], { readField }) {
      return comments.filter(comment => idToRemove !== readField("id", comment));
    },
  },
});

• This API gracefully handles cases where multiple field values are associated with a single field name, and also removes the need for updating the cache by reading a query or fragment, modifying the result, and writing the modified result back into the cache. Behind the scenes, the cache.evict method is now implemented in terms of cache.modify.
• @benjamn in #5909 and #6178
• InMemoryCache provides a new API for storing client state that can be updated from anywhere:

const v = cache.makeVar(123)
console.log(v()) // 123
console.log(v(v() + 1)) // 124
console.log(v()) // 124
v("asdf") // TS type error

• These variables are reactive in the sense that updating their values invalidates any previously cached query results that depended on the old values.
• @benjamn in #5799
• Various cache read and write performance optimizations, cutting read and write times by more than 50% in larger benchmarks.
• @benjamn in #5948
• The cache.readQuery and cache.writeQuery methods now accept an options.id string, which eliminates most use cases for cache.readFragment and cache.writeFragment, and skips the implicit conversion of fragment documents to query documents performed by cache.{read,write}Fragment.
• @benjamn in #5930
• Several deprecated methods have been fully removed:
• ApolloClient#initQueryManager
• QueryManager#startQuery
• ObservableQuery#currentResult
• Support cache.identify(entity) for easily computing entity ID strings.
• @benjamn in #5642
• Support eviction of specific entity fields using cache.evict(id, fieldName).
• @benjamn in #5643
• Make InMemoryCache#evict remove data from all EntityStore layers.
• @benjamn in #5773
• Stop paying attention to previousResult in InMemoryCache.
• @benjamn in #5644
• Improve optimistic update performance by limiting cache key diversity.
• @benjamn in #5648
• Custom field read functions can read from neighboring fields using the readField(fieldName) helper, and may also read fields from other entities by calling readField(fieldName, objectOrReference).
• @benjamn in #5651
• Utilities that were previously externally available through the apollo-utilities package are now only available by importing from @apollo/client/utilities.
• @hwillson in #5683
• Make sure all graphql-tag public exports are re-exported.
• @hwillson in #5861
• Fully removed prettier. The Apollo Client team has decided to no longer automatically enforce code formatting across the codebase. In most cases existing code styles should be followed as much as possible, but this is not a hard and fast rule.
• @hwillson in #5227
• Make sure ApolloContext plays nicely with IE11 when storing the shared context.
• @ms in #5840
• Expose cache modify and identify to the mutate update function.
• @hwillson in #5956
• Add a default gc implementation to ApolloCache.
• @justinwaite in #5974
• Updated to work with graphql@15.
• @durchanek in #6194 and #6279
• @hagmic in #6328
• Apollo Client now supports setting a new ApolloLink (or link chain) after new ApolloClient() has been called, using the ApolloClient#setLink method.
• @hwillson in #6193

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