How to properly decorate request in TypeScript #5100
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I'm trying this code and it fails to compile and throws an error. Compile Error Fastify version: tsconfig.json {
"compilerOptions": {
"target": "ES2017",
"module": "commonjs",
"rootDir": "./src",
"allowJs": false,
"outDir": "./dist",
"noEmitOnError": true,
"preserveConstEnums": true,
"esModuleInterop": true,
"forceConsistentCasingInFileNames": true,
"strict": true,
"noImplicitAny": true,
"strictNullChecks": true,
"strictFunctionTypes": true,
"strictPropertyInitialization": true,
"useUnknownInCatchVariables": true,
"alwaysStrict": true,
"noUnusedLocals": true,
"noUnusedParameters": true,
"noImplicitReturns": true,
"noUncheckedIndexedAccess": true,
"allowUnreachableCode": true,
"skipLibCheck": true,
"experimentalDecorators": true
},
"include": ["./src/**/*.ts"],
"exclude": ["node_modules"]
} |
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Replies: 8 comments 2 replies
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Hey! Remember to do declare module 'fastify' {
interface FastifyRequest {
user: {
id: number
}
}
} |
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In my declare module 'fastify' {
interface FastifyRequest {
user: {
id: number;
};
}
} |
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You need to do the augmentation on the same place as the application code, otherwise, it rewrites the module type definition, leading to errors. A working example might be: import { fastify } from 'fastify';
declare module 'fastify' {
interface FastifyRequest {
user: {
id: number;
};
}
}
const server = fastify();
server.decorateRequest('user', null);
server.addHook('preHandler', (request, _reply, done) => {
request.user = { id: 10001 };
done();
});
server.get('/', (request, reply) => {
console.log(request.user);
reply.code(200).send({ success: true });
}); |
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Attached my |
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@metcoder95 Thanks! But augmenting interface in "scripts": {
"build": "tsc ",
"start": "node ./dist/server.js",
"dev": "ts-node --files ./src/server.ts "
},I was able to figure this out when I directly tried building and it did not give any error at compile time. Again Thanks for your help. |
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create file fastify.d.ts in src/@types declare module "fastify" {
export interface FastifyInstance<
HttpServer = http.Server,
HttpRequest = http.IncomingMessage,
HttpResponse = http.ServerResponse
> {
blipp(): void; // declare here
}
} |
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How to make it work in the instance level? The accepted solution adds the type to all requests, even those that didn't use For example what they ask here: https://stackoverflow.com/questions/73056086/how-to-separately-type-fastify-decorators-in-different-plugins |
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I was 5 minutes away from scraping my Fastify app and switching back to Hono.js. I was just trying to add some context to my request and all the official documentation did was show me how to make things worse. The one post in this thread fixed my issue. The only reason to not use Hono is that the OpenAPI integration is horrible. |
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Hi 👋 Check out the official Fastify demo, it features a fully typed application with 100% test coverage: Also, I recently introduced a new way of working with decorators via the Here’s a working example: interface IUser {
name: string
}
server.register(async function (fastify) {
const usersRepository = fastify.getDecorator<PostgreUsersRepository>(
'usersRepository'
)
fastify.decorateRequest('user', null)
fastify.addHook('onRequest', async (req, reply) => {
req.setDecorator<IUser>('user', { name: 'Jean' })
})
fastify.get('/me', (request, reply) => {
return request.getDecorator<IUser>('user')
})
})Let me know if you have any questions or feedback! |
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That works nicely, no additional typescript hacks to get it working. |
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You need to do the augmentation on the same place as the application code, otherwise, it rewrites the module type definition, leading to errors. A working example might be: