A REST API backend for a personal journaling application built with Spring Boot and MongoDB Atlas. Users can create accounts and manage journal entries scoped to their profile.

---

Tech stack

• Java 17
• Spring Boot
• Spring Data MongoDB
• MongoDB Atlas
• Lombok

---

Project structure

src/main/java/com/example/yashjournal/
├── controller/
│   ├── UserController.java
│   └── JournalEntryController_v2.java
├── services/
│   ├── UserService.java
│   └── JournalEntryService.java
├── repository/
│   ├── UserRepo.java
│   └── JournalEntryRepo.java
└── entity/
    ├── User.java
    └── JournalEntry.java

---

Setup

Prerequisites

• Java 17+
• Maven
• A MongoDB Atlas account with a cluster ready

Configuration

This project requires a MongoDB connection string. Do not commit your credentials.

Copy the example config and fill in your values:

cp src/main/resources/application.properties.example src/main/resources/application.properties

Then edit application.properties:

spring.data.mongodb.uri=mongodb+srv://<username>:<password>@<cluster>.mongodb.net/<dbname>
spring.application.name=yashjournal

Run

mvn spring-boot:run

The server starts on http://localhost:8080.

---

API reference

Users

Method	Endpoint	Description
GET	/users	Get all users
POST	/users	Create a new user
GET	/users/{username}	Get user by username
PUT	/users/{username}	Update user by username
DELETE	/users/{username}	Delete user by username

Create user — request body

{
  "username": "boss",
  "password": "1234"
}

---

Journal entries

Method	Endpoint	Description
GET	/journal	Get all entries (all users)
GET	/journal/{username}	Get all entries for a user
POST	/journal/{username}	Create entry for a user
PUT	/journal/{id}	Update entry by ID
DELETE	/journal/{id}	Delete entry by ID

Create journal entry — request body

{
  "title": "Day 1",
  "content": "Today was a good day."
}

---

Data model

User

Field	Type	Notes
user_id	String	Auto-generated by MongoDB
username	String	Unique, required
password	String	Required
journalEntries	List	@DBRef to journal_entries collection

JournalEntry

Field	Type	Notes
id	String	Auto-generated by MongoDB
title	String	Required
content	String	Optional

---

How entries are linked to users

When a journal entry is created via POST /journal/{username}, the entry is first saved to the journal_entries collection. Its generated ID is then pushed into the corresponding user's journalEntries array in the users collection using a @DBRef reference. This means MongoDB stores a reference (not a copy) of the entry inside the user document.

---

Notes

• application.properties is gitignored — never commit your Atlas credentials
• Passwords are stored as plain text — this is a learning project, not production ready
• No authentication layer is implemented yet