Spring Batch Bean Validation example #SpringBatch

DemoValidationApplication.java

package com.example.demovalidation;

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

@SpringBootApplication
public class DemoValidationApplication {

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

JobConfiguration.java

package com.example.demovalidation;

import java.util.Arrays;

import org.springframework.batch.core.Job;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.item.ItemProcessor;
import org.springframework.batch.item.ItemReader;
import org.springframework.batch.item.ItemWriter;
import org.springframework.batch.item.support.ListItemReader;
import org.springframework.batch.item.validator.SpringValidator;
import org.springframework.batch.item.validator.ValidatingItemProcessor;
import org.springframework.batch.item.validator.Validator;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@EnableBatchProcessing
public class JobConfiguration {

	@Autowired
	private JobBuilderFactory jobs;

	@Autowired
	private StepBuilderFactory steps;

	@Bean
	public ItemReader<Person> itemReader() {
		Person person1 = new Person(1, "foo");
		Person person2 = new Person(2, "");
		return new ListItemReader<>(Arrays.asList(person1, person2));
	}

	@Bean
	public ItemWriter<Person> itemWriter() {
		return list -> {
			for (Person person : list) {
				System.out.println("person = " + person);
			}
		};
	}

	@Bean
	public org.springframework.validation.Validator validator() {
		// see https://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#validation-beanvalidation-spring
		return new org.springframework.validation.beanvalidation.LocalValidatorFactoryBean();
	}

	@Bean
	public Validator<Person> springValidator() {
		SpringValidator<Person> springValidator = new SpringValidator<>();
		springValidator.setValidator(validator());
		return springValidator;
	}

	@Bean
	public ItemProcessor<Person, Person> itemProcessor() {
		ValidatingItemProcessor<Person> validatingItemProcessor = new ValidatingItemProcessor<>(springValidator());
		validatingItemProcessor.setFilter(true);
		return validatingItemProcessor;
	}

	@Bean
	public Step step1() {
		return steps.get("step1")
				.<Person, Person>chunk(1)
				.reader(itemReader())
				.processor(itemProcessor())
				.writer(itemWriter())
				.build();
	}

	@Bean
	public Job job() {
		return jobs.get("job")
				.start(step1())
				.build();
	}
	
	// can use a listener to log invalid items to file, db, etc
	// use #afterProcess or #onProcessError depending on validatingItemProcessor.setFilter to true or false
	static class InvalidItemsListener implements ItemProcessListener<Person, Person> {

		@Override
		public void beforeProcess(Person person) {
		}

		@Override
		public void afterProcess(Person person, Person result) {
			if (result == null) {
				System.out.println(person + " has been filtered because it is invalid");
			}
		}

		@Override
		public void onProcessError(Person person, Exception e) {
			System.out.println(person + " is invalid due to " + e.getMessage() );
		}
	}

}

Person.java

package com.example.demovalidation;

import javax.validation.constraints.NotEmpty;

public class Person {

	private int id;

	@NotEmpty
	private String name;

	public Person() {
	}

	public Person(int id, String name) {
		this.id = id;
		this.name = name;
	}

	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;
	}

	@Override
	public String toString() {
		return "Person{" +
				"id=" + id +
				", name='" + name + '\'' +
				'}';
	}
}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>com.example</groupId>
	<artifactId>demo-validation</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>demo-validation</name>
	<description>Demo project for Spring Boot</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.2.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>
	</properties>

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

		<dependency>
			<groupId>org.hsqldb</groupId>
			<artifactId>hsqldb</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>org.springframework.batch</groupId>
			<artifactId>spring-batch-test</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>


</project>

@netrapalsingh Looks like I missed the notification about your comment.. sorry for that.

Good question. There are two ways to do it depending on how you decide to deal with invalid items: either you filter them, or you throw an exception. This is configured with the filter flag: validatingItemProcessor.setFilter(true);. So:

• If you decide to filter them, you can use ItemProcessListener#afterProcess method
• If you decide to throw an exception, you can use ItemProcessListener#onError method

Here is a quick example:

class InvalidItemsListener implements ItemProcessListener<Person, Person> {

	@Override
	public void beforeProcess(Person person) {
	}

	@Override
	public void afterProcess(Person person, Person result) {
		if (result == null) {
			System.out.println(person + " has been filtered because it is invalid");
		}
	}

	@Override
	public void onProcessError(Person person, Exception e) {
		System.out.println(person + " is invalid due to " + e.getMessage() );
	}
} 

This example writes info to the standard output, but you can update it to write to a file. Of course, you need to register this listener in the step. Let me know if this helps.

Hi Benas,

I am reading the records from a csv file, I need to do validate the recodes and write errors to a file with line numbers, how can I get access to line number?

Thanks,
Agru

@agru-capco There is an interface called ItemCountAware that sets the number on each item. It could work in your case since the item number would be the same as the line number. What you need to do is make Person implement ItemCountAware and log the line number in the file.