Week 4 - Rest APIs

Java Annotations

Introduction to REST

Spring Boot Setup

Writing Endpoints

Message Formats

Input Validation

Practice

Assignment

• Teachers

Back end Track

Content

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Let’s get practical

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Practice exercises are optional and do not need to be submitted

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Exercise 1 - REST Design: Notes API

In this exercise, you will design a small REST API before writing any code. The API manages personal notes.

A note has these fields:

• id
• title
• content
• tag
• pinned

Tasks

For each action in the table below:

• Write down the HTTP method and URI, for the endpoint covering this action
• The body (actual content) of the request and its Content-Type
• The body of the response and its Content-Type

The first row is pre-filled as an example.

Exercise 2  - Build a Notes API

In this exercise, you will build the API you designed in Exercise 1. You will practice Spring Boot controllers, composed mapping annotations, @PathVariable, @RequestParam, @RequestBody, and ResponseEntity.

• Create a new project with Spring Initializr https://start.spring.io
  • Group: net.hackyourfuture
  • Artifact: NotesAPI
  • Add the dependencies you need for this API. You can also add Validation this time.
• Create the below structure (Including the files) under your main package, src/main/java/net/hackyourfuture/NotesAPI

Package Structure

📂 note/
├── 📄 NoteController.java
└── 📂 models/
    └── 📄 Note.java

Acceptance criteria

Exercise 3

In this exercise you’ll expand the controller in Exercise 2 to be working with DTOs and keep your Note model internal. This will make the API boundary clearer.

Package Structure

📂 note/
├── 📄 NoteController.java
├── 📂 dto/
│   ├── 📂 request/
│   │   ├── 📄 CreateNoteRequest.java
│   │   └── 📄 UpdateNoteRequest.java
│   └── 📂 response/
│       └── 📄 NoteResponse.java
└── 📂 models/
    └── 📄 Note.java

Tasks

• Implement CreateNoteRequest
• Implement UpdateNoteRequest
• Implement NoteResponse

Exercise 4

Now make your Notes API reject invalid input. You will practice Jakarta Bean Validation, @Valid, and a global exception handler.

Validation Dependency

If you haven’t added the validation dependency, you can add the below to pom.xml and reload Maven:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-validation</artifactId>
</dependency>

Acceptance Criteria

• Limit property text sizes for Create and Update requests:
  • title with length between 3-80 characters.
  • content with max length of 2000
  • tag with max length 30

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