apollo-cache-inmemory

1.6.6 verified Sat Apr 25 auth: no javascript deprecated

apollo-cache-inmemory is the recommended cache implementation for Apollo Client 2.x, providing a normalized data store without Redux dependency. Version 1.6.6 is the final release; this package is deprecated in favor of @apollo/client which bundles InMemoryCache starting from Apollo Client 3.0. The cache uses a normalized data store with configurable dataIdFromObject, supports readQuery, readFragment, writeQuery, writeFragment for direct cache access, and includes a heuristic fragment matcher with optional introspection support for unions/interfaces. Releases adhere to Apollo Client's schedule (monthly patches, minor releases less frequent). Key differentiator: seamless integration with Apollo Client without external state management.

Common errors

error Error: You are using the simple (heuristic) fragment matcher, but your queries contain union or interface types. Apollo Client cannot match fragments on unions/interfaces without an introspection fragment matcher. ↓

cause Default heuristic fragment matcher cannot handle unions or interfaces.

fix

Pass an IntrospectionFragmentMatcher created from your schema's introspection data to InMemoryCache: new InMemoryCache({ fragmentMatcher: new IntrospectionFragmentMatcher({ introspectionQueryResultData }) }).

error TypeError: Cannot read property 'id' of undefined ↓

cause Cache lookup using readFragment or readQuery with an object reference that doesn't exist in the cache.

fix

Ensure the data has been written to the cache first (e.g., after a query or writeQuery). Check that the fragment or query matches the cache shape exactly.

error Error: Could not find result for store key: ... ↓

cause Accessing a cache entry that does not exist or has been evicted.

fix

Verify the cache key format (default: typename:id) and ensure the data is present. Avoid evicting needed data.

error Invariant Violation: You must pass a graphql document to the query option of ... ↓

cause Passing a string instead of a parsed GraphQL document (gql) to cache methods.

fix

Use the gql tag from 'graphql-tag' to parse the query before passing it: import gql from 'graphql-tag'; cache.readQuery({ query: gql... }).

Warnings

deprecated Package apollo-cache-inmemory is deprecated. Use @apollo/client instead. ↓

fix Replace import { InMemoryCache } from 'apollo-cache-inmemory' with import { InMemoryCache } from '@apollo/client'. In Apollo Client 3.0+, the cache is bundled.

gotcha The InMemoryCache constructor uses a heuristic fragment matcher by default which silently drops union/interface fragments. ↓

fix If using fragments on unions or interfaces, provide an IntrospectionFragmentMatcher configured with your schema's possibleTypes.

breaking Apollo Client 3.0 (and @apollo/client) changes the cache API significantly; apollo-cache-inmemory is no longer compatible. ↓

fix Upgrade to @apollo/client and use its InMemoryCache with type policies instead of custom resolvers.

gotcha dataIdFromObject defaults to using path-based keys if id or _id are missing, causing duplicate objects to be stored separately. ↓

fix Provide a custom dataIdFromObject function that returns a stable unique identifier for each object (e.g., based on __typename and primary key).

deprecated The CacheResolver API is deprecated and removed in Apollo Client 3.0. ↓

fix Use type policies in @apollo/client's cache instead.

Install

npm install apollo-cache-inmemory

yarn add apollo-cache-inmemory

pnpm add apollo-cache-inmemory

Imports

InMemoryCache
wrong
```
const InMemoryCache = require('apollo-cache-inmemory').InMemoryCache
```
correct
```
import { InMemoryCache } from 'apollo-cache-inmemory'
```
Default export does not exist; use named import. With Apollo Client 3.0+, import from '@apollo/client' instead.

IntrospectionFragmentMatcher

wrong

import IntrospectionFragmentMatcher from 'apollo-cache-inmemory'

correct

import { IntrospectionFragmentMatcher } from 'apollo-cache-inmemory'

Only needed for GraphQL schema with unions or interfaces. Import from same package.

defaultDataIdFromObject
```
import { defaultDataIdFromObject } from 'apollo-cache-inmemory'
```
Utility for generating default cache keys based on __typename and id/_id.
CacheResolver
```
import { CacheResolver } from 'apollo-cache-inmemory'
```
Deprecated in Apollo Client 3.0; use type policies instead.

Quickstart

Initialize InMemoryCache and ApolloClient with a GraphQL endpoint, then execute a query.

import { InMemoryCache } from 'apollo-cache-inmemory';
import { HttpLink } from 'apollo-link-http';
import ApolloClient from 'apollo-client';

const cache = new InMemoryCache({
  addTypename: true,
  dataIdFromObject: (object) => object.id || object._id,
});

const client = new ApolloClient({
  link: new HttpLink({ uri: 'https://api.example.com/graphql' }),
  cache,
});

client.query({ query: gql`{ hello }` }).then(result => console.log(result));