Google Login Process with Firebase in TypeScript: Solving the 'propertyToJSON not exist' Error

Google Login Process with Firebase and TypeScript: Solving "Property does not exist on type JSON" Error

Introduction

In this article, we'll discuss the process of implementing Google login with Firebase using TypeScript, while addressing the "Property does not exist on type JSON" error commonly encountered during the user data extraction process. The article assumes a basic understanding of TypeScript, Firebase, and Prisma-firebase-admin.

Implementing Google Login with Firebase

1. Set up your Firebase project and configure Google Sign-In:

   a. Create a new Firebase project on the Firebase Console.

   b. Enable Google Sign-In under the Authentication tab.

   c. Download the JSON configuration file (google-services.json) and place it in the root of your project.

2. Create a new Angular project:

   a. Use the Angular CLI (ng new my-app) to create a new project.

   b. Install the firebase (npm install firebase) and angularfire2 (npm install angularfire2) packages.

3. Initialize Firebase within your Angular application:

   a. Import the AngularFireModule and AngularFireAuthModule from angularfire2.

   b. Register the Firebase app within the imports array in the app.module.ts.

   c. Initialize Firebase in the main.ts.

4. Create a Google Sign-In component:

   a. Implement a SignInComponent that will trigger the Google Sign-In process.

   b. Use the AngularFireAuth service (this.afAuth.signInWithPopup(new firebase.auth.GoogleAuthProvider())) to start the Google Sign-In flow.

5. Extract User Data:

   a. Once the user is logged in, you can extract their details using the this.afAuth.authState.subscribe() method.

   b. Here, you might encounter the "Property does not exist on type JSON" error when trying to access specific user properties.

Solving "Property does not exist on type JSON" Error

The issue occurs due to TypeScript's strict type checking. To resolve it, you can use one of the following methods:

Method 1: Use the as keyword

Cast the user object to a firebase.User type:

const user = this.afAuth.authState.subscribe((user) => {
  if (user) {
    const displayName = (user as firebase.User).displayName;
    // ...
  }
});

Method 2: Use the any type

Define the user as an any type before accessing its properties:

const user = this.afAuth.authState.subscribe((user) => {
  const userAny: any = user;
  const displayName = userAny.displayName;
  // ...
});

Method 3: Utilize custom types

Define a custom type that includes the required properties, and cast the user to this new type:

type CustomUser = {
  displayName?: string;
  email?: string;
  // ...
};

const user = this.afAuth.authState.subscribe((user) => {
  if (user) {
    const customUser = user as CustomUser;
    const displayName = customUser.displayName;
    // ...
  }
});

Extracting User Data with Prisma-firebase-admin

1. Set up Prisma-firebase-admin:

   a. Install the prisma-firebase-admin package (npm install prisma-firebase-admin) and initialize it within your project.

   b. Import the FirebaseService from prisma-firebase-admin and initialize it with your Firebase configuration.

2. Extract user details:

   a. The FirebaseService allows you to access user details via a simple RESTful API, avoiding issues with the "Property does not exist..." error.

   b. Utilize the getUser method provided by the FirebaseService to extract the user's details and store them within your database:

   this.firebaseService.getUser(user.uid).subscribe((userDetails: any) => {
       // Store user details in your database
     });
   

Conclusion

This article covered the implementation of Google login with Firebase using TypeScript and the process of extracting user data while addressing the "Property does not exist on type JSON" error. Additionally, the article explored the usage of Prisma-firebase-admin to extract user information.

References

• Firebase Console
• Angular CLI
• Understanding TypeScript Types
• Firebase Google Sign-In
• AngularFire2
• Prisma-firebase-admin
• Firebase Admin SDK