Spring Boot GraphQL REST API - GET Function using Query Mapping

Learn how to get started with Graphql using spring boot framework. In this article, you will be learning like how to add the schema details and mapping the function and request payload with Graphql @QueryMapping into your controller class. You need Spring web, JPA, Mysql, Lombok and Spring Graphql dependencies to your pom module.

schema.graphqls (This file should be created inside the resources/graphql folder)

type Query{
    findAll: [User]
    userById(id: ID): User
}

type User{
    id: ID
    name: String
    gender: String
    emailId: String
}

UserGQLController .java

package com.hakeemit.graphql.controller;

import com.hakeemit.graphql.entity.User;
import com.hakeemit.graphql.entity.UserDetails;
import com.hakeemit.graphql.service.UserServices;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.graphql.data.method.annotation.Argument;
import org.springframework.graphql.data.method.annotation.MutationMapping;
import org.springframework.graphql.data.method.annotation.QueryMapping;
import org.springframework.stereotype.Controller;

import java.util.List;

@Controller
public class UserGQLController {

    @Autowired
    private UserServices userServices;

    @QueryMapping
    public List findAll(){
        return userServices.getAllUser();
    }
    
        @QueryMapping
    public User userById(@Argument int id){
        return userServices.userById(id);
    }

}

@QueryMapping will be the entry point just like REST API Get Mapping.

UserServices .java

package com.hakeemit.graphql.service;

import com.hakeemit.graphql.entity.User;
import com.hakeemit.graphql.entity.UserDetails;
import com.hakeemit.graphql.repositories.UserRepositories;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

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

@Service
public class UserServices {

    @Autowired
    private UserRepositories userRepositories;

    public User userById(int id){
        Optional user = userRepositories.findById(id);
        return user.get();
    }
    public List getAllUser(){
        return userRepositories.findAll();
    }
    }

pom.xml add the dependencies

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</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-web</artifactId>
</dependency>

<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <scope>runtime</scope>
</dependency>

Start running your application 

http://localhost:8080/graphiql?path=/graphql

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