How to Fix NestJS 9.4.0 Crashing Issue While Creating Fastify App

Описание: Discover the solution to the `NestJS 9.4.0 crashes` that occur when using Fastify and Passport.js. Learn how to avoid common pitfalls with practical code examples.
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How to Fix NestJS 9.4.0 Crashing Issue While Creating Fastify App

Creating applications with NestJS and Fastify offers exciting opportunities, especially for implementing security features like CSRF protection. However, you may encounter issues when integrating Passport.js for authentication, leading to crashes in your application. In this guide, we will address a common problem you might face when using these technologies together and provide a robust solution.

The Problem: Crash When Using Fastify with Passport.js

When you attempt to add throttling to your NestJS application using Fastify, you might run into an error that crashes the app. Specifically, if you encounter an error message like res.setHeader is not a function, this indicates a compatibility issue between Fastify and the Passport.js OAuth strategies.

Understanding the Error

The error suggests that Fastify's response object (FastifyReply) doesn't have a method that Passport.js expects to be present. This happens because Fastify approaches requests and responses differently than Express, which is where many Passport strategies originated.

The Solution: Decorate FastifyRequest and FastifyReply

To solve this issue, you need to override the Fastify response methods that Passport expects to be present. This can be done by using Fastify's decorate functionality. Below, we provide the necessary code snippet to modify the FastifyReply and FastifyRequest objects correctly.

Step-by-Step Guide to Implement the Fix

Open your main.ts file where you set up your NestJS application.

Before calling the app.listen() method, add the following code snippet:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code

addHook: This allows you to add a custom hook to Fastify. In this case, we are checking if the request is encrypted when in production mode.

decorateReply: This modifies the FastifyReply object.

setHeader: We define this method to correctly set headers, which is a requirement of Passport.

end: We define this method to properly end the response, also needed by Passport.

Final Thoughts

Integrating Passport.js with Fastify in a NestJS application requires some additional steps due to the differences in how responses are handled. By following the steps outlined above, you should be able to avoid the crashing issue associated with the res.setHeader is not a function error.

Don't forget to test your application thoroughly after making these changes to ensure everything works smoothly. With this fix, you can confidently implement security features like CSRF protection in your NestJS Fastify application.

By addressing this common issue, you’ll harness the benefits of using NestJS and Fastify effectively, creating robust and secure applications.