README.md

Library Management System - GraphQL API

This project is a Library Management System built using GraphQL, Express, and MongoDB. It provides a set of mutations and queries to manage users, books, libraries, and borrowed books. The API is designed to handle user authentication, book borrowing, and library management.

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Table of Contents

• Library Management System - GraphQL API
  • Table of Contents
  • Features
  • Technologies Used
  • Setup Instructions
    • Prerequisites
    • Installation
  • API Documentation
    • Mutations
    • Queries
  • Validation
  • Error Handling

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Features

• User Management: Signup, login, and delete users.
• Book Management: Add, borrow, and mark books as available.
• Library Management: Fetch libraries along with their books.
• Authentication: JWT-based authentication for secure access.
• Validation: Input validation for all mutations and queries.
• Error Handling: Structured error responses for better debugging.

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Technologies Used

• GraphQL: For building the API.
• Express: For the server.
• MongoDB: For database storage.
• Mongoose: For MongoDB object modeling.
• JWT: For user authentication.
• Joi: For input validation.
• Bcrypt: For password hashing.

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Setup Instructions

Prerequisites

• Node.js (v14 or higher)
• MongoDB (local or cloud instance)
• Postman (for testing)

Installation

1. Clone the repository:

   git clone https://github.com/your-username/library-management-graphql.git
   cd library-management-graphql

2. Install dependencies:

   npm install

3. Set up environment variables: Create a .env file in the root directory and add the following:

   PORT=3000
   MONGODB_URI=mongodb://localhost:27017/library
   JWT_SECRET=your_jwt_secret_key

4. Start the server:

   npm start

5. Access the GraphQL Playground: Open your browser and navigate to:

   http://localhost:3000/graphql
   

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API Documentation

Mutations

1. Signup

   • Description: Register a new user.
   • Request:

     mutation {
       signUpMutation(
         name: "John Doe",
         email: "john@example.com",
         phone: "1234567890",
         password: "password123"
       ) {
         statusCode
         message
         user {
           _id
           name
           email
           phone
         }
       }
     }

2. Login

   • Description: Authenticate a user and return JWT tokens.
   • Request:

     mutation {
       loginMutation(
         email: "john@example.com",
         password: "password123"
       ) {
         statusCode
         message
         token
         refreshToken
       }
     }

3. Add Book

   • Description: Add a new book to the library.
   • Request:

     mutation {
       addBook(
         title: "Sample Book",
         author: "authorId",
         publishedYear: 2021,
         genre: "Fiction",
         availableCopies: 5
       ) {
         _id
         title
         author
       }
     }

4. Borrow Book

   • Description: Borrow a book for 2 days.
   • Request:

     mutation {
       borrowBook(
         userId: "userId",
         bookId: "bookId"
       ) {
         _id
         userId
         bookId
         borrowedAt
         dueDate
       }
     }

5. Delete User

   • Description: Delete a user (authenticated users only).
   • Request:

     mutation {
       deleteUser(id: "userId") {
         _id
         name
         email
       }
     }

6. Mark Book as Available

   • Description: Mark a borrowed book as available again.
   • Request:

     mutation {
       markBookAvailable(id: "bookId") {
         _id
         title
         availableCopies
       }
     }

Queries

1. Retrieve All Books

   • Description: Fetch all books in the library.
   • Request:

     query {
       getBooks {
         _id
         title
         author
         genre
         availableCopies
       }
     }

2. Retrieve Book by ID

   • Description: Fetch a book by its ID.
   • Request:

     query {
       getBookById(id: "bookId") {
         _id
         title
         author
         publishedYear
         genre
       }
     }

3. Fetch Libraries with Books

   • Description: Fetch libraries along with the books they contain.
   • Request:

     query {
       getLibraries {
         _id
         name
         location
         books {
           _id
           title
           author
         }
       }
     }

4. Retrieve Overdue Borrowed Books

   • Description: Fetch overdue borrowed books that have not been returned.
   • Request:

     query {
       getOverdueBooks {
         _id
         userId
         bookId
         dueDate
       }
     }

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Validation

All mutations and queries are validated using Joi. The following fields are validated:

• Email: Must be a valid email address.
• Password: Must be at least 8 characters long and contain at least one letter and one number.
• Phone: Must be a 11-digit number.
• Published Year: Must be a valid year.

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Error Handling

Errors are returned in a structured format with the following fields:

• message: A descriptive error message.
• statusCode: The HTTP status code (e.g., 400, 404, 500).
• errorCode: A custom error code for easier debugging.

Example:

{
  "errors": [
    {
      "message": "User not found",
      "statusCode": 404,
      "errorCode": "USER_NOT_FOUND"
    }
  ],
  "data": null
}