Thursday 13 July 2023

Micronaut: @RequestBean: bind any bindable value to bean object

@RequestBean annotaiton bind the Bindable parameters to a Bean object.

 

For example, below snippet bind the query parameters (from,to) to the NumbersMeta object.

 

Example

@Get(value = "/even-numbers", produces = MediaType.TEXT_PLAIN)
public String evenNumbers(@RequestBean NumbersMeta numbersMeta) {

}

@Introspected
public class NumbersMeta {
	@Nullable
	private Integer from;

	@Nullable
	private Integer to;
}

 

Find the below working application.

 

Step 1: Create new maven project ‘micronaut-rest-requestbean-demo’.

 

Step 2: Update pom.xml with maven dependencies.

 

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.sample.app</groupId>
	<artifactId>micronaut-rest-requestbean-demo</artifactId>
	<version>0.1</version>
	<packaging>jar</packaging>

	<parent>
		<groupId>io.micronaut</groupId>
		<artifactId>micronaut-parent</artifactId>
		<version>3.7.4</version>
	</parent>

	<properties>
		<packaging>jar</packaging>
		<jdk.version>11</jdk.version>
		<release.version>11</release.version>
		<micronaut.version>3.7.3</micronaut.version>
		<micronaut.runtime>netty</micronaut.runtime>
		<exec.mainClass>com.sample.app.App</exec.mainClass>
	</properties>

	<repositories>
		<repository>
			<id>central</id>
			<url>https://repo.maven.apache.org/maven2</url>
		</repository>
	</repositories>

	<dependencies>
		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-inject</artifactId>
			<scope>compile</scope>
		</dependency>
		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-validation</artifactId>
			<scope>compile</scope>
		</dependency>
		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-http-client</artifactId>
			<scope>compile</scope>
		</dependency>
		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-http-server-netty</artifactId>
			<scope>compile</scope>
		</dependency>
		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-jackson-databind</artifactId>
			<scope>compile</scope>
		</dependency>
		<dependency>
			<groupId>jakarta.annotation</groupId>
			<artifactId>jakarta.annotation-api</artifactId>
			<scope>compile</scope>
		</dependency>
		<dependency>
			<groupId>ch.qos.logback</groupId>
			<artifactId>logback-classic</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>io.micronaut.test</groupId>
			<artifactId>micronaut-test-junit5</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>org.junit.jupiter</groupId>
			<artifactId>junit-jupiter-api</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>org.junit.jupiter</groupId>
			<artifactId>junit-jupiter-engine</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>io.micronaut.build</groupId>
				<artifactId>micronaut-maven-plugin</artifactId>
			</plugin>

			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<configuration>
					<!-- Uncomment to enable incremental compilation -->
					<!-- <useIncrementalCompilation>false</useIncrementalCompilation> -->

					<annotationProcessorPaths
						combine.children="append">
						<path>
							<groupId>io.micronaut</groupId>
							<artifactId>micronaut-http-validation</artifactId>
							<version>${micronaut.version}</version>
						</path>
					</annotationProcessorPaths>

				</configuration>
			</plugin>
		</plugins>
	</build>

</project>

 

Step 3: Define NumbersMeta model class.

 

NumbersMeta.java

 

package com.sample.app.model;

import io.micronaut.core.annotation.Introspected;
import io.micronaut.core.annotation.Nullable;

@Introspected
public class NumbersMeta {
	@Nullable
	private Integer from;

	@Nullable
	private Integer to;

	public Integer getFrom() {
		return from;
	}

	public void setFrom(Integer from) {
		this.from = from;
	}

	public Integer getTo() {
		return to;
	}

	public void setTo(Integer to) {
		this.to = to;
	}

}

 

Step 4: Define HelloController class.

 

HelloController.java

 

package com.sample.app.controller;

import java.util.StringJoiner;

import com.sample.app.model.NumbersMeta;

import io.micronaut.http.MediaType;
import io.micronaut.http.annotation.Controller;
import io.micronaut.http.annotation.Get;
import io.micronaut.http.annotation.RequestBean;

@Controller("/hello")
public class HelloController {

	@Get(value = "/even-numbers", produces = MediaType.TEXT_PLAIN)
	public String evenNumbers(@RequestBean NumbersMeta numbersMeta) {

		Integer from = numbersMeta.getFrom();
		Integer to = numbersMeta.getTo();

		if (from == null || from < 0) {
			from = 0;
		}

		if (to == null || to < 0) {
			to = from + 10;
		}

		final StringJoiner stringJoiner = new StringJoiner(",");

		for (int i = from; i < to; i += 2) {
			stringJoiner.add("" + i);
		}

		return stringJoiner.toString();
	}
}

 

Step 5: Define main application class.

 

App.java

 

package com.sample.app;

import io.micronaut.runtime.Micronaut;

public class App {

	public static void main(String[] args) {
		Micronaut.run(App.class);

		// Use this if you want the beans to be initialized eagerly
		/*
		 * Micronaut.build(args) .eagerInitSingletons(true) .mainClass(App.class)
		 * .start();
		 */
	}
}

 

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-rest-requestbean-demo-0.1.jar’ in project target folder.

 

$ls ./target/
classes
generated-sources
generated-test-sources
maven-archiver
maven-status
micronaut-rest-requestbean-demo-0.1.jar
original-micronaut-rest-requestbean-demo-0.1.jar
test-classes

Execute below command to run the application.

java -jar ./target/micronaut-rest-requestbean-demo-0.1.jar

Run below curl command to test the api.

curl --location --request GET 'http://localhost:8080/hello/even-numbers/?from=2&to=20'

$curl --location --request GET 'http://localhost:8080/hello/even-numbers/?from=2&to=20'
2,4,6,8,10,12,14,16,18

You can download this application from this link.




 

 

 

 

 

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