GraphQL ID Variable

GraphQL supports the reuse of variables in Query Operation. The most used variable in any API is ID and Operation is Find By Id

package org.wesome.graphql.controllers;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.graphql.data.method.annotation.Argument;
import org.springframework.graphql.data.method.annotation.QueryMapping;
import org.springframework.stereotype.Controller;
import org.wesome.graphql.entity.Apple;
import org.wesome.graphql.service.AppleService;

import java.util.List;
import java.util.Optional;

@Controller
public class AppleGraphQLController {
    @Autowired
    private AppleService appleService;

    @QueryMapping("findAppleById")
    Optional<Apple> findAppleById(@Argument int appleId) {
        return appleService.findAppleById(appleId);
    }

    @QueryMapping("findAllApple")
    List<Apple> findAllApple() {
        return appleService.findAllApple();
    }
}

package org.wesome.graphql.entity;

public record Apple(int appleId, String appleName, String taste) {
}

package org.wesome.graphql.service;

import org.wesome.graphql.entity.Apple;

import java.util.List;
import java.util.Optional;

public interface AppleService {
    Optional<Apple> findAppleById(int appleId);

    List<Apple> findAllApple();
}

package org.wesome.graphql.service;


import org.springframework.stereotype.Service;
import org.wesome.graphql.entity.Apple;

import java.util.ArrayList;
import java.util.List;
import java.util.Optional;

@Service
public class AppleServiceImpl implements AppleService {
    private static final List<Apple> apples = new ArrayList<>(List.of(new Apple(1, "Macintosh", "sweet"), new Apple(2, "Fuji", "tangy"), new Apple(3, "Gala", "bitter"), new Apple(4, "Jonagold", "sour")));

    @Override
    public Optional<Apple> findAppleById(int id) {
        return apples.stream().filter(apple -> apple.appleId() == id).findFirst();
    }

    @Override
    public List<Apple> findAllApple() {
        return apples;
    }
}

package org.wesome.graphql;

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

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

\src\main\resources\graphql\schema.graphqls

# Apple Object
type Apple{
    # primary key of apple
    appleId:ID!
    # apple Name
    appleName:String
    # apple Taste
    taste:String
}
# Apple Query
type Query{
    # query to get all apples
    findAllApple:[Apple]
    # query to get apple by id
    findAppleById(appleId:ID!):Apple
}

\src\main\resources\application.properties

spring.graphql.graphiql.enabled=true

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"
         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>3.1.5</version>
        <relativePath/>
    </parent>
    <groupId>org.wesome</groupId>
    <artifactId>spring-boot-graphql</artifactId>
    <version>0.0.1-snapshot</version>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-graphql</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webflux</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.graphql</groupId>
            <artifactId>spring-graphql-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <name>spring boot graphql</name>
    <description>implementing graphql in spring boot</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

GraphiQL

GraphQL provides an inbuild UserInterface GraphiQL, which can be accessed via http://localhost:8080/graphiql or access GraphQL via Postman, in the query section add the below query

For variable, declare the below JSON

{
    "appleId": 1
}

now Query will be able to use the variables declared, let's see

query FindAppleById($appleId: ID!) {
    findAppleById(appleId: $appleId) {
        appleId
        appleName
        taste
    }
}

query FindAppleById {
    findAppleById(appleId: "1") {
        appleId
        appleName
        taste
    }
}