Spring Boot 4 Microservices & REST APIs · Lesson

CRUD Operations with REST

Implement Create, Read, Update, and Delete operations for your entities via REST endpoints.

CRUD Operations with REST is a free Spring Boot 4 Microservices & REST APIs lesson on CoddyKit — lesson 5 of 6. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Spring Boot 4 Microservices & REST APIs learning path, one of 6 lessons in the course, and your progress syncs across the web and the CoddyKit app.

CRUD Operations: The Basics

Welcome to implementing CRUD operations with Spring Boot! CRUD stands for Create, Read, Update, and Delete.

These are the four fundamental operations for persistent storage, allowing you to manage data in your application.

In REST APIs, each CRUD operation typically maps to a specific HTTP method.

Mapping CRUD to HTTP Methods

Understanding how CRUD maps to HTTP methods is key for RESTful design:

Create (C): Handled by POST requests.
Read (R): Handled by GET requests.
Update (U): Handled by PUT requests.
Delete (D): Handled by DELETE requests.

We'll use a simple Product entity and its ProductRepository from previous lessons.

Implementing Create (POST)

To create a new resource, we use the POST HTTP method. In Spring Boot, this is handled by the @PostMapping annotation.

The new product data is sent in the request body, which Spring automatically maps to our Product object using @RequestBody.

Create Product Example

Here's how you'd create an endpoint to add a new product. Run it, then try adding a product via a tool like Postman (e.g., POST to /api/products with JSON body {"name": "Laptop", "price": 1200.0}).

package com.coddykit.crud;

import jakarta.persistence.*;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
import org.springframework.web.bind.annotation.*;
import org.springframework.beans.factory.annotation.Autowired;

@Entity
public class Product {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private double price;
    public Product() {}
    public Product(String name, double price) {
        this.name = name;
        this.price = price;
    }
    public Long getId() { return id; }
    public void setId(Long id) { this.id = id; }
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    public double getPrice() { return price; }
    public void setPrice(double price) { this.price = price; }
}

@Repository
interface ProductRepository extends JpaRepository<Product, Long> {}

@RestController
@RequestMapping("/api/products")
class ProductController {
    @Autowired
    private ProductRepository productRepository;

    @PostMapping
    public Product createProduct(@RequestBody Product product) {
        return productRepository.save(product);
    }
}

@SpringBootApplication
class CrudApplication {
    public static void main(String[] args) {
        SpringApplication.run(CrudApplication.class, args);
    }
}

Implementing Read (GET)

Reading resources is done with the GET HTTP method. We'll create two types of read operations:

Get all products: Maps to @GetMapping.
Get a single product by ID: Maps to @GetMapping("/{id}") using a @PathVariable.

When fetching by ID, we use Optional to handle cases where the product might not exist.

Read Products Example

This code adds methods to fetch all products and a single product by its ID. Notice the use of ResponseEntity to return a 404 if a product isn't found.

package com.coddykit.crud;

import jakarta.persistence.*;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
import org.springframework.web.bind.annotation.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import java.util.List;
import java.util.Optional;

@Entity
public class Product {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private double price;
    public Product() {}
    public Product(String name, double price) {
        this.name = name;
        this.price = price;
    }
    public Long getId() { return id; }
    public void setId(Long id) { this.id = id; }
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    public double getPrice() { return price; }
    public void setPrice(double price) { this.price = price; }
}

@Repository
interface ProductRepository extends JpaRepository<Product, Long> {}

@RestController
@RequestMapping("/api/products")
class ProductController {
    @Autowired
    private ProductRepository productRepository;

    @GetMapping
    public List<Product> getAllProducts() {
        return productRepository.findAll();
    }

    @GetMapping("/{id}")
    public ResponseEntity<Product> getProductById(@PathVariable Long id) {
        Optional<Product> product = productRepository.findById(id);
        return product.map(ResponseEntity::ok)
                      .orElseGet(() -> ResponseEntity.notFound().build());
    }
}

@SpringBootApplication
class CrudApplication {
    public static void main(String[] args) {
        SpringApplication.run(CrudApplication.class, args);
    }
}

Implementing Update (PUT)

To update an existing resource, we use the PUT HTTP method, annotated with @PutMapping.

The endpoint typically includes the resource's ID in the path (/{id}) to identify which item to update, and the updated data is sent in the @RequestBody.

Update Product Example

This method updates an existing product. It first checks if the product exists using the ID from the path. If found, it updates the fields from the request body and saves it.

package com.coddykit.crud;

import jakarta.persistence.*;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
import org.springframework.web.bind.annotation.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import java.util.Optional;

@Entity
public class Product {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private double price;
    public Product() {}
    public Product(String name, double price) {
        this.name = name;
        this.price = price;
    }
    public Long getId() { return id; }
    public void setId(Long id) { this.id = id; }
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    public double getPrice() { return price; }
    public void setPrice(double price) { this.price = price; }
}

@Repository
interface ProductRepository extends JpaRepository<Product, Long> {}

@RestController
@RequestMapping("/api/products")
class ProductController {
    @Autowired
    private ProductRepository productRepository;

    @PutMapping("/{id}")
    public ResponseEntity<Product> updateProduct(
        @PathVariable Long id, @RequestBody Product productDetails) {
        Optional<Product> product = productRepository.findById(id);
        if (product.isPresent()) {
            Product existingProduct = product.get();
            existingProduct.setName(productDetails.getName());
            existingProduct.setPrice(productDetails.getPrice());
            return ResponseEntity.ok(productRepository.save(existingProduct));
        } else {
            return ResponseEntity.notFound().build();
        }
    }
}

@SpringBootApplication
class CrudApplication {
    public static void main(String[] args) {
        SpringApplication.run(CrudApplication.class, args);
    }
}

Implementing Delete (DELETE)

To remove a resource, we use the DELETE HTTP method, annotated with @DeleteMapping.

Similar to update, the ID of the resource to delete is passed as a @PathVariable. After deletion, it's common to return a 204 No Content status.

Delete Product Example

This method deletes a product by ID. It finds the product and, if present, deletes it. Returning ResponseEntity.noContent().build() is a good practice for successful deletions.

package com.coddykit.crud;

import jakarta.persistence.*;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
import org.springframework.web.bind.annotation.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import java.util.Optional;

@Entity
public class Product {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private double price;
    public Product() {}
    public Product(String name, double price) {
        this.name = name;
        this.price = price;
    }
    public Long getId() { return id; }
    public void setId(Long id) { this.id = id; }
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    public double getPrice() { return price; }
    public void setPrice(double price) { this.price = price; }
}

@Repository
interface ProductRepository extends JpaRepository<Product, Long> {}

@RestController
@RequestMapping("/api/products")
class ProductController {
    @Autowired
    private ProductRepository productRepository;

    @DeleteMapping("/{id}")
    public ResponseEntity<Void> deleteProduct(@PathVariable Long id) {
        Optional<Product> product = productRepository.findById(id);
        if (product.isPresent()) {
            productRepository.delete(product.get());
            return ResponseEntity.noContent().build();
        } else {
            return ResponseEntity.notFound().build();
        }
    }
}

@SpringBootApplication
class CrudApplication {
    public static void main(String[] args) {
        SpringApplication.run(CrudApplication.class, args);
    }
}

Quick Check: HTTP Methods

Which HTTP method is typically used to update an existing resource in a REST API, and which one is for creating a new resource?

Recap: CRUD with REST

You've successfully learned how to implement all four CRUD operations using Spring Boot REST controllers!

Create: Use @PostMapping.
Read: Use @GetMapping (for all or by ID).
Update: Use @PutMapping.
Delete: Use @DeleteMapping.

These are the building blocks for almost any data-driven API. Next, we'll explore validation and error handling!

Frequently asked questions

Is the “CRUD Operations with REST” lesson free?

Yes — the full text of “CRUD Operations with REST” is free to read here on the web, and the Spring Boot 4 Microservices & REST APIs course includes 6 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Spring Boot 4 Microservices & REST APIs course, upgrade to CoddyKit PRO.

What will I learn in “CRUD Operations with REST”?

Implement Create, Read, Update, and Delete operations for your entities via REST endpoints. You practise Spring Boot 4 Microservices & REST APIs with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Spring Boot 4 Microservices & REST APIs?

No prior experience is required. Spring Boot 4 Microservices & REST APIs on CoddyKit is structured for beginners through advanced learners; this is — lesson 5 of 6, so you can start here or from the beginning and move at your own pace.

How long does the “CRUD Operations with REST” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Spring Boot 4 Microservices & REST APIs lesson?

Yes. Every Spring Boot 4 Microservices & REST APIs lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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