User Registration Flow (Backend): Implement User Service and Controller

[ashishkarki]

Here’s what we’ll do next:

1. Create a User Service:

This will handle the logic for user registration, including creating a new user in the database.

2. Create a User Controller:

The controller will handle incoming HTTP requests and forward them to the service.

3. Create the DTO (Data Transfer Object):

The DTO will define the structure of the data being passed in for user registration.

[ashishkarki]

1. PostgreSQL with Prisma Setup

• We set up PostgreSQL as the database using Neon (cloud-hosted Postgres).
• Prisma was integrated as the ORM (Object-Relational Mapping) tool.
• We defined the User model in Prisma, which includes fields like id, name, email, dob, citizenship, passportNumber, and password.
• Constraints were added, such as ensuring that the email is unique, non-empty, and properly formatted.

2. NestJS Application Setup

• The server-side framework NestJS was configured to handle the business logic of the application.
• We created the UserService class in NestJS, which handles user-related operations such as registering users.
• Prisma’s user.create method was used to create new users in the database, with validation rules (e.g., checking for existing emails to prevent duplicates).
• DTO (Data Transfer Object): We created the RegisterUserDto class with validation decorators like @IsNotEmpty(), @IsEmail(), @MinLength(), and more for strong data validation.

3. GraphQL API Integration

• We used GraphQL as the API layer, allowing clients to register users via mutations.
• Resolvers were created to handle GraphQL mutations.
  • We set up the register mutation to accept the RegisterUserDto and register users in the database.

4. Custom Response Object

• We designed a custom OperationResult DTO to return standardized responses with a status (boolean) and message (string). This response is sent back to the client after each operation, ensuring consistency in the API’s behavior.

5. Service Logic Overview

• UserService:
  • Checks if the email already exists in the database using findUnique().
  • If the email is not in use, it creates a new user record with a unique ID and stores the raw password (for now).
  • Returns an OperationResult containing the status of the operation and the user object in a formatted message.