Micronaut: Validate data classes using @Valid annotation

In this post, I am going to explain how to use javax.validation.Valid to trigger cascading validation on data classes or POJOs.

 

Step 1: Define data class and make sure that it is annotated with @Introspected annotation.

@Introspected
public class Employee {

	@Positive
	private int id;
	
	@NotBlank
	private String name;
	
	@Min(18)
	private int age;

	...........
	...........
}

  Step 2: Use @Valid annotation on bean methods to trigger cascading validation.

@Singleton
public class EmployeeService {

	public void registerEmployee(@Valid Employee employee) {
		System.out.println("Employee registered successfully " + employee);
	}
}

 

Find the below working application.

 

Step 1: Create new maven project ‘micronaut-valid-annotaiton-demo’.

 

Step 2: Update pom.xml with maven dependencies.

 

pom.xml

 

<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.sample.app</groupId>
	<artifactId>micronaut-valid-annotaiton-demo</artifactId>
	<version>1</version>

	<properties>
		<maven-compiler-plugin.version>3.8.1</maven-compiler-plugin.version>
		<micronaut.version>3.7.3</micronaut.version>
		<slf4j.version>2.0.3</slf4j.version>
		<maven-compiler-plugin.version>3.8.1</maven-compiler-plugin.version>

		<maven.compiler.target>15</maven.compiler.target>
		<maven.compiler.source>15</maven.compiler.source>
	</properties>

	<dependencies>

		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-inject-java</artifactId>
			<version>${micronaut.version}</version>
		</dependency>
		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-runtime</artifactId>
			<version>${micronaut.version}</version>
		</dependency>

		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-validation</artifactId>
			<version>${micronaut.version}</version>
		</dependency>


		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-api</artifactId>
			<version>${slf4j.version}</version>
		</dependency>
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-simple</artifactId>
			<version>${slf4j.version}</version>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<artifactId>maven-assembly-plugin</artifactId>
				<configuration>
					<archive>
						<manifest>
							<mainClass>com.sample.app.App</mainClass>
						</manifest>
					</archive>
					<descriptorRefs>
						<descriptorRef>jar-with-dependencies</descriptorRef>
					</descriptorRefs>
				</configuration>

				<executions>
					<execution>
						<id>make-assembly</id>
						<phase>package</phase>
						<goals>
							<goal>single</goal>
						</goals>
					</execution>
				</executions>
			</plugin>

		</plugins>
	</build>
</project>

 

Step 3: Define Employee model class.

 

Employee.java

 

package com.sample.app.model;

import javax.validation.constraints.Min;
import javax.validation.constraints.NotBlank;
import javax.validation.constraints.Positive;

import io.micronaut.core.annotation.Introspected;

@Introspected
public class Employee {

	@Positive
	private int id;
	
	@NotBlank
	private String name;
	
	@Min(18)
	private int age;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	@Override
	public String toString() {
		return "Employee [id=" + id + ", name=" + name + ", age=" + age + "]";
	}

	
}

 

Step 4: Define EmployeeService class.

 

EmployeeService.java

package com.sample.app.service;

import javax.validation.Valid;

import com.sample.app.model.Employee;

import jakarta.inject.Singleton;

@Singleton
public class EmployeeService {

	public void registerEmployee(@Valid Employee employee) {
		System.out.println("Employee registered successfully " + employee);
	}
}

 

Step 5: Define main application class.

 

App.java

 

package com.sample.app;

import com.sample.app.model.Employee;
import com.sample.app.service.EmployeeService;

import io.micronaut.context.ApplicationContext;

public class App {

	public static void main(String[] args) {
		try (ApplicationContext applicationContext = ApplicationContext.run()) {
			EmployeeService employeeService = applicationContext.getBean(EmployeeService.class);
			
			Employee emp = new Employee();
			emp.setAge(5);
			emp.setId(1);
			emp.setName("Krishna");
			employeeService.registerEmployee(emp);
		}

	}
}

 

Total project structure looks like below.

 

 

Build the project using mvn package command.

Navigate to the folder where pom.xml is located and execute the command ‘mvn package’.

 

Upon command successful execution, you can see the jar file ‘micronaut-valid-annotaiton-demo-1-jar-with-dependencies.jar’ in project target folder.

$ls ./target/
archive-tmp
classes
generated-sources
maven-archiver
maven-status
micronaut-valid-annotaiton-demo-1-jar-with-dependencies.jar
micronaut-valid-annotaiton-demo-1.jar
test-classes

 

Execute below command to run the application.

java -jar ./target/micronaut-valid-annotaiton-demo-1-jar-with-dependencies.jar

$java -jar ./target/micronaut-valid-annotaiton-demo-1-jar-with-dependencies.jar
Exception in thread "main" javax.validation.ConstraintViolationException: registerEmployee.employee.age: must be greater than or equal to 18
	at io.micronaut.validation.ValidatingInterceptor.intercept(ValidatingInterceptor.java:111)
	at io.micronaut.aop.chain.MethodInterceptorChain.proceed(MethodInterceptorChain.java:137)
	at com.sample.app.service.$EmployeeService$Definition$Intercepted.registerEmployee(Unknown Source)
	at com.sample.app.App.main(App.java:18)

You can download this application from this link.

 

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