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Hey guys in this post, we will add validations to the GraphQL schema with Spring Boot Example. This is a continuation of the previous post, please follow that post before proceeding with this.

Complete example

Let’s create a step-by-step spring boot project and Add validation to the GraphQL schema

Read More:

• Check the complete GraphQL and Spring Boot Tutorials
• Check the complete Spring Boot Data JPA Tutorials

Create spring boot project

There are many different ways to create a spring boot application, you can follow the below articles to create one –

>> Create spring boot application using Spring initializer
>> Create spring boot application in Spring tool suite [STS]
>> Create spring boot application in IntelliJ IDEA

Add maven dependencies

Open pom.xml and add the following dependencies –

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.5.2</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>in.bushansirgur</groupId>
	<artifactId>springbootgraphql</artifactId>
	<version>v1</version>
	<name>springbootgraphql</name>
	<description>Spring data jpa</description>
	<properties>
		<java.version>1.8</java.version>
	</properties>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<dependency>
		    <groupId>com.graphql-java</groupId>
		    <artifactId>graphql-spring-boot-starter</artifactId>
		    <version>5.0.2</version>
		</dependency>
		<dependency>
		    <groupId>com.graphql-java</groupId>
		    <artifactId>graphiql-spring-boot-starter</artifactId>
		    <version>5.0.2</version>
		</dependency>
		<dependency>
		    <groupId>com.graphql-java</groupId>
		    <artifactId>graphql-java-tools</artifactId>
		    <version>5.2.4</version>
		</dependency>
		
	</dependencies>

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

</project>

spring-boot-starter-web dependency for building web applications using Spring MVC. It uses the tomcat as the default embedded container.

graphql-spring-boot-starter dependency is the starter dependency for GraphQL and spring boot. graphiql-spring-boot-starter dependency provides the interface to test GraphQL queries. graphql-java-tools dependency helps us to scan the graphql files having the extension .graphqls

Create a Request class

Create SampleRequest.java inside the in.bushansirgur.springboot.model package and add the following content

package in.bushansirgur.springboot.model;

public class SampleRequest {

	private String firstName;
	
	private String lastName;

	public String getFirstName() {
		return firstName;
	}

	public void setFirstName(String firstName) {
		this.firstName = firstName;
	}

	public String getLastName() {
		return lastName;
	}

	public void setLastName(String lastName) {
		this.lastName = lastName;
	}
}

This class is a simple POJO class, contains private fields, setters, getters, and toString().

Create a service class

Create Home.java inside the in.bushansirgur.springboot.resolver package and add the following content

package in.bushansirgur.springboot.resolver;

import org.springframework.stereotype.Service;

import com.coxautodev.graphql.tools.GraphQLQueryResolver;

import in.bushansirgur.springboot.model.SampleRequest;

@Service
public class Home implements GraphQLQueryResolver{
	
	public String fullName(SampleRequest sRequest) {
		return sRequest.getFirstName() + " " + sRequest.getLastName();
	}

	public String home () {
		return null;
	}
}

Create a schema

Create home.graphqls file inside the schema folder and place it inside the resources folder

Note: filename and folder doesn’t matter here you can create with any file name and folder but it should have the extension .graphqls

type Query {
	fullName(sampleRequest: SampleRequest): String
        home: String!
}
input SampleRequest {
	firstName: String!,
	lastName: String
}

We will add ![Exclamtory] at the end of the type indicating that it should not return null. It should always return non-nullable value.

Run the app

Run the application using the below maven command –

mvn spring-boot:run

Open the Altair plugin in chrome and execute the following query-

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