Spring Boot CRUD Example with PostgreSQL

Spring-MVC-CRUD-Operations

In this tutorial, you will build a simple CRUD application (Create, Read, Update, Delete) in Spring Boot.

We will use

Spring Data JPA to interact with the database

PostgreSQL as the database

REST API to expose CRUD endpoints

1. Create Database Table

Create a table in your PostgreSQL database

CREATE TABLE product (
    id SERIAL PRIMARY KEY,
    name VARCHAR(100),
    quantity INTEGER,
    price DOUBLE PRECISION
);

id is auto-incremented using a PostgreSQL sequence.

2. Project Structure

src/main/java/com/quipoin/crud/example/
 ├─ controller/
 │   └─ ProductController.java
 ├─ entity/
 │   └─ Product.java
 ├─ repository/
 │   └─ ProductRepository.java
 ├─ service/
 │   └─ ProductService.java
 └─ SpringBootCrudExample2Application.java
pom.xml

3. Main Application Class

package com.quipoin.crud.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringBootCrudExample2Application {
    public static void main(String[] args) {
        SpringApplication.run(SpringBootCrudExample2Application.class, args);
    }
}

4. Product Entity

package com.quipoin.crud.example.entity;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class Product {
    @Id
    @GeneratedValue
    private int id;
    private String name;
    private int quantity;
    private double price;

    public Product() {}

    // Constructor, getters, and setters
    // (keep your IDE to auto-generate or write them as shown earlier)
}

5. Product Repository

package com.quipoin.crud.example.repository;

import org.springframework.data.jpa.repository.JpaRepository;
import com.quipoin.crud.example.entity.Product;

public interface ProductRepository extends JpaRepository<Product, Integer> {
    Product findByName(String name);
}

6. Product Service

Handles business logic

package com.quipoin.crud.example.service;

import com.quipoin.crud.example.entity.Product;
import com.quipoin.crud.example.repository.ProductRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;

@Service
public class ProductService {
    @Autowired
    private ProductRepository repository;

    public Product saveProduct(Product product) {
        return repository.save(product);
    }

    public List<Product> saveProducts(List<Product> products) {
        return repository.saveAll(products);
    }

    public List<Product> getProducts() {
        return repository.findAll();
    }

    public Product getProductById(int id) {
        return repository.findById(id).orElse(null);
    }

    public Product getProductByName(String name) {
        return repository.findByName(name);
    }

    public String deleteProduct(int id) {
        repository.deleteById(id);
        return "Product removed !! " + id;
    }

    public Product updateProduct(Product product) {
        Product existingProduct = repository.findById(product.getId()).orElse(null);
        if (existingProduct != null) {
            existingProduct.setName(product.getName());
            existingProduct.setQuantity(product.getQuantity());
            existingProduct.setPrice(product.getPrice());
            return repository.save(existingProduct);
        }
        return null;
    }
}

7. Product Controller

Exposes RESTful endpoints

package com.quipoin.crud.example.controller;

import com.quipoin.crud.example.entity.Product;
import com.quipoin.crud.example.service.ProductService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;

@RestController
public class ProductController {
    @Autowired
    private ProductService service;

    @PostMapping("/addProduct")
    public Product addProduct(@RequestBody Product product) {
        return service.saveProduct(product);
    }

    @PostMapping("/addProducts")
    public List<Product> addProducts(@RequestBody List<Product> products) {
        return service.saveProducts(products);
    }

    @GetMapping("/products")
    public List<Product> findAllProducts() {
        return service.getProducts();
    }

    @GetMapping("/productById/{id}")
    public Product findProductById(@PathVariable int id) {
        return service.getProductById(id);
    }

    @GetMapping("/product/{name}")
    public Product findProductByName(@PathVariable String name) {
        return service.getProductByName(name);
    }

    @PutMapping("/update")
    public Product updateProduct(@RequestBody Product product) {
        return service.updateProduct(product);
    }

    @DeleteMapping("/delete/{id}")
    public String deleteProduct(@PathVariable int id) {
        return service.deleteProduct(id);
    }
}

8. pom.xml

Contains dependencies for Spring Boot, Spring Data JPA, PostgresSQL

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.postgresql</groupId>
        <artifactId>postgresql</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

9. How it works

Spring Boot runs your application

Controller handles HTTP requests

Service contains business logic

Repository handles database operations

10. Run your project

mvn spring-boot:run

Access REST API

GET all products - /products

POST new product - /addProduct

etc.

Conclusion

Using Spring Boot + Spring Data JPA, you can build CRUD applications quickly.

Simple

Maintainable

Scalable

If you had like, I can also help add

Swagger API docs

Custom exception handling

Frontend (Angular / React) to consume this API