apollo-link-deep-dedup
A custom Apollo Link library for resolving GraphQL query against cache as much as possible and issuing minimal requests.
Motivation
The implementation of Apollo client results in sending full queries to the server over the network, which can be partially fulfilled by the cached data.
Resolving every query with cached data as much as possible and issuing the minimal request to the server reduces the size of data transferring over the network, and alleviates the query resolution work on the server on an each-query basis.
Features
Apollo client writes the data from every query to the cache as normalized objects. For every query, deepDedupLink
- resolves the query against the cache
- gets partial results from cache
- removes fully-resolved fields from the query
- sends query to downstream links (e.g.
httpLink
for issuing request to the server) - merges partial results from both cache and server
- sends full result to upstream links
deepDedupLink
deduplicates queries thoroughly. Even with very nested queries, it is able to deduplicate the query at every-field level (see below example).
It currently only supports apollo-cache-inmemory
and bypasses deduplication on non-query operations (e.g. mutation
and subscription
) and fields with directives
and fragments
.
Example
First query
query {
authors {
id
firstName
posts {
id
votes
}
}
press {
name
address
}
}
Second query without deduplication
query {
authors {
id
firstName
lastName
posts {
id
votes
title
}
}
press {
name
address
}
}
Second query with deduplication (the one that gets sent to the server)
query {
authors {
lastName
posts {
title
}
}
}
Installation
npm install apollo-link-deep-dedup --save
Usage
import InMemoryCache from 'apollo-cache-inmemory';
import { DeepDedupLink } from 'apollo-link-deep-dedup';
const cache = new InMemoryCache();
const deepDedupLink = new DeepDedupLink({ cache });
Use link with apollo client and other links
import ApolloClient from 'apollo-client';
import InMemoryCache from 'apollo-cache-inmemory';
import { ApolloLink } from 'apollo-link';
// import DeepDedupLink
import { DeepDedupLink } from 'apollo-link-deep-dedup';
// cache used by apollo client
const cache = new InMemoryCache();
// pass in the cache as an option to initialize deepDedupLink
const deepDedupLink = new DeepDedupLink({ cache });
// compose apollo links
const link = ApolloLink.from([
// ...upstreamLinks,
deepDedupLink,
// ...downstreamLinks (e.g. httpLink),
]);
// initialize apollo client with the cache and links
const client = new ApolloClient({
link,
cache,
});
Options
deepDedupLink
takes an object with one required cache
option
-
cache
: the same cache object passed in when initializingApolloClient
Context
deepDedupLink
can be overridden by using the context on a per operation basis:
-
forceFetch
: a boolean (defaults to false) to bypass deduplication per request
// a query with apollo-client that will not be deduplicated
client.query({
query: MY_QUERY,
context: {
forceFetch: true,
}
});
Development
git clone https://github.com/instructure/apollo-link-deep-dedup.git
npm install
npm run watch
A development guide can be found here.