Use Relay as React hooks
Install react-relay and relay-hooks using yarn or npm:
yarn add react-relay relay-hooks
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The initial purpose of the library was to provide the ability to use all react-relay HOCs as react hooks and to implement the store-or-network and store-only policies used by the react-relay-offline library to manage offline relay applications
After Relay's core team shared information about the the initial differences in the issue relay-tools#5, all the necessary changes were made in order to make relay-hooks as close as possible to their specifications.
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current differences with upcoming Relay Hooks in react-relay
- useLazyLoadQuery: returns a single data object with the query's data, and nothing else.
- useFragment: not use suspense
- usePagination: not use suspense
- useRefetchable: not use suspense
- useMutation: not use suspense
- useSubscription: not use suspense
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what's more in relay-hooks
- useQuery: it is the same as
useLazyLoadQuerybut does not use suspense, it allows you to use hooks without having to migrate the application in concurrent mode and its return is the same as the QueryRenderer HOC - useRefetch: it is the same as
useRefetchable, allows you to migrate the Refetch Container without changing the fragment specifications - conditional useQuery & useLazyLoadQuery: added
skip: [Optional] If skip is true, the query will be skipped entirely
- useQuery: it is the same as
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why use relay-hooks?
It is a stable library and none of its dependencies is experimental and it allows you to immediately use react hooks with relay-runtime and it is designed for easy migration to react-relay hooks.
It is a light library and compatible with react-relay
Since queries with useQuery no longer set context, we will expose a new RelayEnvironmentProvider component that takes an environment and sets it in context;
variables will no longer be part of context.
A RelayEnvironmentProvider should be rendered once at the root of the app, and multiple useQuery's can be rendered under this environment provider.
ReactDOM.render(
<RelayEnvironmentProvider environment={modernEnvironment}>
<AppTodo/>
</RelayEnvironmentProvider>,
rootElement,
);useQuery does not take an environment as an argument. Instead, it reads the environment set in the context; this also implies that it does not set any React context.
In addition to query (first argument) and variables (second argument), useQuery accepts a third argument options.
options
fetchPolicy: determine whether it should use data cached in the Relay store and whether to send a network request. The options are:
store-or-network(default): Reuse data cached in the store; if the whole query is cached, skip the network requeststore-and-network: Reuse data cached in the store; always send a network request.network-only: Don't reuse data cached in the store; always send a network request. (This is the default behavior of Relay's existingQueryRenderer.)store-only: Reuse data cached in the store; never send a network request.
fetchKey: [Optional] A fetchKey can be passed to force a refetch of the current query and variables when the component re-renders, even if the variables didn't change, or even if the component isn't remounted (similarly to how passing a different key to a React component will cause it to remount). If the fetchKey is different from the one used in the previous render, the current query and variables will be refetched.
networkCacheConfig: [Optional] Object containing cache config options for the network layer. Note the the network layer may contain an additional query response cache which will reuse network responses for identical queries. If you want to bypass this cache completely, pass {force: true} as the value for this option.
skip: [Optional] If skip is true, the query will be skipped entirely.
import {useQuery, graphql } from 'relay-hooks';
const query = graphql`
query appQuery($userId: String) {
user(id: $userId) {
...TodoApp_user
}
}
`;
const variables = {
userId: 'me',
};
const options = {
fetchPolicy: 'store-or-network', //default
networkCacheConfig: undefined,
}
const AppTodo = function (appProps) {
const {props, error, retry, cached} = useQuery(query, variables, options);
if (props && props.user) {
return <TodoApp user={props.user} />;
} else if (error) {
return <div>{error.message}</div>;
}
return <div>loading</div>;
}same to useQuery
import * as React from 'react';
import {useQuery, graphql, RelayEnvironmentProvider } from 'relay-hooks';
const query = graphql`
query appQuery($userId: String) {
user(id: $userId) {
...TodoApp_user
}
}
`;
class ErrorBoundary extends React.Component {
state = { error: null };
componentDidCatch(error) {
this.setState({ error });
}
render() {
const { children, fallback } = this.props;
const { error } = this.state;
if (error) {
return React.createElement(fallback, { error });
}
return children;
}
}
const variables = {
userId: 'me',
};
const options = {
fetchPolicy: 'store-or-network', //default
networkCacheConfig: undefined,
}
const AppTodo = function (appProps) {
const {props, cached} = useLazyLoadQuery(query, variables, options);
return <TodoApp user={props.user} />;
}
const App = (
<RelayEnvironmentProvider environment={modernEnvironment}>
<ErrorBoundary fallback={({ error }) => `Error: ${error.message + ': ' + error.stack}`}>
<React.Suspense fallback={<div>loading suspense</div>}>
<AppTodo />
</React.Suspense>
</ErrorBoundary>
</RelayEnvironmentProvider>
);the useOssFragment is a hooks not provided in the official version of react-relay. Using it you can manage fragment, refetch and pagination containers. For reasons of cost of migration to the react-relay version it is recommended to use the other hooks.