The best way to understand how to use subscriptions hooks is to play with the configuration.
// wundergraph.config.ts
const counter = introspect.graphql({
id: 'counter',
apiNamespace: 'ws',
loadSchemaFromString: schema,
url: 'http://localhost:4000/graphql',
});
configureWunderGraphApplication({
apis: [counter],
});// wundergraph.server.ts
export default configureWunderGraphServer(() => ({
hooks: {
global: {
wsTransport: {
onConnectionInit: {
// counter is the id of the introspected api (data source id), defined in the wundergraph.config.ts
enableForDataSources: ['counter'],
hook: async (hook) => {
let token = hook.clientRequest.headers.get('Authorization') || '';
// we can have a different logic for each data source
if (hook.dataSourceId === 'counter') {
token = 'secret';
}
return {
// this payload will be passed to the ws `connection_init` message payload
// {"type": "connection_init", "payload": {"Authorization": "secret"}}
payload: {
Authorization: token,
},
};
},
},
},
},
queries: {},
mutations: {},
subscriptions: {
// .wundergraph/operations/Ws.graphql
Ws: {
mutatingPreResolve: async (hook) => {
// here we modify the input before request is sent to the data source
hook.input.from = 7;
return hook.input;
},
postResolve: async (hook) => {
// here we log the response we got from the ws server (not the modified one)
hook.log.info(`postResolve hook: ${hook.response.data!.ws_countdown}`);
},
mutatingPostResolve: async (hook) => {
// here we modify the response before it gets sent to the client
let count = hook.response.data!.ws_countdown!;
count++;
hook.response.data!.ws_countdown = count;
return hook.response;
},
preResolve: async (hook) => {
// here we log the request input
/**
* // .wundergraph/operations/Ws.graphql
* subscription($from: Int!) {
* ws_countdown(from: $from)
* }
*/
hook.log.info(`preResolve hook input, counter starts from: ${hook.input.from}`);
},
},
},
},
graphqlServers: [],
}));npm install && npm startcurl -N 'http://localhost:9991/operations/Ws?from=5'- Check the output.
- Check the logs to see the hooks being executed.
curl -N http://localhost:9991/operations/users/get?id=1Read the Docs.
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