Data

Tools

Indexes

Applications

Experiments

Awesome

An open API service indexing awesome lists of open source software.

https://github.com/hardyscc/java-graphql-sample

Build a basic CRUD backend application in Java Spring Boot with GraphQL & MySQL.
https://github.com/hardyscc/java-graphql-sample

graphql graphql-java graphql-java-kickstart graphql-spqr java lombok mybatis-migrations mysql spring-boot spring-doc

Last synced: 2 months ago
JSON representation

Build a basic CRUD backend application in Java Spring Boot with GraphQL & MySQL.

Awesome Lists containing this project

README 

          
# Java GraphQL Backend Tutorial



## Overview



Build a basic CRUD backend application in Java Spring Boot with GraphQL & MySQL.



## Technologies



1. [Java](https://www.oracle.com/java/)

2. [Spring Boot](https://spring.io/projects/spring-boot)

3. [Maven](https://maven.apache.org/)

4. [GraphQL Spring Framework Boot Starters](https://github.com/graphql-java-kickstart/graphql-spring-boot)

5. [MySQL](https://www.mysql.com/)

6. [MyBatis Migrations](http://mybatis.org/migrations/)



## Create an Empty Project



### Download the template of an Empty Project



Setup an empty project using [Spring Initializr](https://start.spring.io/).



1. Update the field "Artifact" as `java-graphql-sample`.



2. Update the field "Package name" as `com.example.jgs`.



3. Press `ADD DEPENDENCIES...` button to add the following dependency: `Spring Web`.



> Please use Maven Project in Java 8, packaging as JAR for this tutorial.



Press the `GENERATE` button to download an empty project template.

Extract the zip folder to start editing.



### Add a Default Controller



Create the following file `src/main/java/com/example/jgs/controller/HealthController.java`.



```java

package com.example.jgs.controller;



import org.springframework.web.bind.annotation.GetMapping;

import org.springframework.web.bind.annotation.RestController;



@RestController

public class HealthController {



    @GetMapping

    public String check() {

        return "OK";

    }

}

```



Start server with below command:



```bash

mvnw spring-boot:run

```



Goto http://localhost:8080 You should see the `OK` message.



## Add GraphQL Dependencies



### Add JPA and GraphQL dependency



Update the `pom.xml` as follow.



```xml

    

        ...

        7.1.0

        0.10.1

    



    

        ...

        

            org.springframework.boot

            spring-boot-starter-data-jpa

        

        

            com.graphql-java-kickstart

            graphql-spring-boot-starter

            ${graphql-java-kickstart.version}

            

                

                    com.graphql-java

                    graphql-java

                

            

        

        

            com.graphql-java-kickstart

            playground-spring-boot-starter

            ${graphql-java-kickstart.version}

            runtime

        

        

            io.leangen.graphql

            spqr

            ${graphql-spqr.version}

        

        

            com.h2database

            h2

            runtime

        

    

...

```



### Create the User Entity and Service



Create the following file `src/main/java/com/example/jgs/input/CreateUser.java`.



```java

package com.example.jgs.input;



import io.leangen.graphql.annotations.GraphQLNonNull;

import lombok.Data;



@Data

public class CreateUser {

    @GraphQLNonNull

    private String name;



    private String nickName;

}

```



Create the following file `src/main/java/com/example/jgs/model/User.java`.



```java

package com.example.jgs.model;



import com.example.jgs.input.CreateUser;

import io.leangen.graphql.annotations.GraphQLNonNull;

import lombok.AllArgsConstructor;

import lombok.Builder;

import lombok.Data;

import lombok.NoArgsConstructor;

import org.hibernate.annotations.Type;



import javax.persistence.Column;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

import java.util.UUID;



@Entity

@Data

@Builder

@AllArgsConstructor

@NoArgsConstructor

public class User {



    @Id

    @GeneratedValue

    @Type(type = "uuid-char")

    @GraphQLNonNull

    @Column(length = 36)

    private UUID id;



    @GraphQLNonNull

    private String name;



    private String nickName;



    public static User from(CreateUser createUser) {

        return User.builder().name(createUser.getName())

                .nickName(createUser.getNickName())

                .build();

    }

}

```



Create the following file `src/main/java/com/example/jgs/repository/UserRepository.java`.



```java

package com.example.jgs.repository;



import com.example.jgs.model.User;

import org.springframework.data.jpa.repository.JpaRepository;

import org.springframework.stereotype.Repository;



import java.util.UUID;



@Repository

public interface UserRepository extends JpaRepository {

}

```



Create the following file `src/main/java/com/example/jgs/service/UserService.java`.



```java

package com.example.jgs.service;



import com.example.jgs.input.CreateUser;

import com.example.jgs.model.User;

import com.example.jgs.repository.UserRepository;

import lombok.AllArgsConstructor;

import org.springframework.stereotype.Service;



import java.util.List;

import java.util.UUID;



@Service

@AllArgsConstructor

public class UserService {



    private final UserRepository userRepository;



    public List find() {

        return this.userRepository.findAll();

    }



    public User findOneById(UUID id) {

        return this.userRepository.findById(id).orElse(null);

    }



    public User create(CreateUser createUser) {

        return this.userRepository.save(User.from(createUser));

    }



    public boolean delete(UUID id) {

        if (this.userRepository.existsById(id)) {

            this.userRepository.deleteById(id);

            return true;

        }

        return false;

    }

}

```



### Implement the User Resolver



Create the following file `src/main/java/com/example/jgs/resolver/UserResolver.java`.



```java

package com.example.jgs.resolver;



import com.example.jgs.input.CreateUser;

import com.example.jgs.model.User;

import com.example.jgs.service.UserService;

import io.leangen.graphql.annotations.GraphQLArgument;

import io.leangen.graphql.annotations.GraphQLMutation;

import io.leangen.graphql.annotations.GraphQLNonNull;

import io.leangen.graphql.annotations.GraphQLQuery;

import lombok.AllArgsConstructor;

import org.springframework.stereotype.Controller;



import java.util.List;

import java.util.UUID;



@Controller

@AllArgsConstructor

public class UserResolver {



    private final UserService userService;



    @GraphQLQuery

    @GraphQLNonNull

    public List<@GraphQLNonNull User> users() {

        return this.userService.find();

    }



    @GraphQLQuery

    public User user(

            @GraphQLArgument(name = "id") UUID id) {

        return this.userService.findOneById(id);

    }



    @GraphQLMutation

    @GraphQLNonNull

    public User createUser(

            @GraphQLArgument(name = "input") @GraphQLNonNull CreateUser createUser) {

        return this.userService.create(createUser);

    }



    @GraphQLMutation

    public UUID deleteUser(

            @GraphQLArgument(name = "id") UUID id) {

        return this.userService.delete(id) ? id : null;

    }

}

```



### Add Config for GraphQL



Create the following file `src/main/java/com/example/jgs/config/GraphqlConfig.java`.



```java

package com.example.jgs.config;



import com.example.jgs.resolver.UserResolver;

import graphql.schema.GraphQLSchema;

import io.leangen.graphql.GraphQLSchemaGenerator;

import lombok.AllArgsConstructor;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;



@Configuration

@AllArgsConstructor

public class GraphqlConfig {



    private final UserResolver userResolver;



    @Bean

    GraphQLSchema schema() {

        return new GraphQLSchemaGenerator()

                .withBasePackages("com.example.jgs")

                .withOperationsFromSingleton(this.userResolver)

                .generate();

    }

}

```



Rename `src/main/resources/application.properties` to `src/main/resources/application.yml`. Then Add the following:



```yml

spring:

  datasource:

    url: jdbc:h2:mem:testdb

```



### Test the GraphQL Endpoint



Start the server.



```bash

mvnw spring-boot:run

```



Goto the GraphQL Playground - http://localhost:8080/playground.



1. Create a new user



   ```graphql

   mutation {

     createUser(input: { name: "Tommy" }) {

       id

     }

   }

   ```



   Output :



   ```json

   {

     "data": {

       "createUser": {

         "id": "8ec8105e-1ffc-4fe3-81fb-882b3dd33f82"

       }

     }

   }

   ```



2. Query the users



   ```graphql

   query {

     users {

       id

       name

     }

   }

   ```



   Output :



   ```json

   {

     "data": {

       "users": [

         {

           "id": "8ec8105e-1ffc-4fe3-81fb-882b3dd33f82",

           "name": "Tommy"

         }

       ]

     }

   }

   ```



## Setup DB and DB migration



### Config MySQL and MyBatis Migrations



Update the following file `pom.xml`



```xml

...

    

        ...

        0.0.2

    



    

        ...

        

            mysql

            mysql-connector-java

            runtime

        

        

            de.bessonov

            mybatis-migrations-spring-boot-autoconfigure

            ${mybatis-migrations-autoconfigure.version}

        

    

...

```



Update the following file `src/main/resources/application.yml`.



```yml

spring:

  datasource:

    url: jdbc:${DATABASE_URL:mysql://usr:User12345@localhost:3306/development}



logging:

  level:

    org.hibernate.SQL: DEBUG

    org.hibernate.type.descriptor.sql.BasicBinder: TRACE



server:

  port: 4000

```



### Initialize the migration scripts



Create a folder `scripts` under `src/main/resources`



Create the following file `src/main/resources/scripts/_create_changelog.sql`  (e.g. 20200728095409_create_changelog.sql )



```sql

-- // Create Changelog



-- Default DDL for changelog table that will keep

-- a record of the migrations that have been run.



-- You can modify this to suit your database before

-- running your first migration.



-- Be sure that ID and DESCRIPTION fields exist in

-- BigInteger and String compatible fields respectively.



CREATE TABLE ${changelog} (

  ID NUMERIC(20,0) NOT NULL,

  APPLIED_AT VARCHAR(25) NOT NULL,

  DESCRIPTION VARCHAR(255) NOT NULL,

  PRIMARY KEY(ID)

);



-- //@UNDO

DROP TABLE ${changelog};

```



Create the following file `src/main/resources/scripts/_first_migration.sql`  (e.g. 20200728095410_first_migration.sql )



```sql

-- // First migration.

-- Migration SQL that makes the change goes here.

CREATE TABLE user (

  id VARCHAR(36) NOT NULL,

  name VARCHAR(255) NOT NULL,

  nick_name VARCHAR(255) NULL,

  PRIMARY KEY(id)

);



-- //@UNDO

-- SQL to undo the change goes here.

DROP TABLE user;

```



> Please note the following points when creating new script: 
 1. The naming convention is `_.sql` 
 2. Put undo SQL under `-- //@UNDO` section.



### Test the migration script



#### Build the jar



Create the following file `src/test/resources/application.yml`.



```yml

spring:

  datasource:

    url: jdbc:h2:mem:testdb



graphql:

  servlet:

    websocket:

      enabled: false

```



Update the dependency of `com.h2database` in `pom.xml` as follow:



```xml

...

		

			com.h2database

			h2

			test

		

...

```



Package the jar by command:



```bash

mvnw package

```



#### Execution of migration command



Start a MySQL docker instance.



```bash

docker run -d -e "MYSQL_ROOT_PASSWORD=Admin12345" -e "MYSQL_USER=usr" -e "MYSQL_PASSWORD=User12345" -e "MYSQL_DATABASE=development" -p 3306:3306 --name some-mysql bitnami/mysql:5.7.27

```



Run the below command and look at migration status before executing the scripts:



```bash

>java -jar target/java-graphql-sample-0.0.1-SNAPSHOT.jar migrations status



ID             Applied At          Description

================================================================================

20200812020020    ...pending...    create changelog

20200812020021    ...pending...    first migration

```



Execution of the migration script:



```bash

java -jar target/java-graphql-sample-0.0.1-SNAPSHOT.jar migrations up

```



Run the below command again to check the applied time:



```bash

>java -jar target/java-graphql-sample-0.0.1-SNAPSHOT.jar migrations status



ID             Applied At          Description

================================================================================

20200812020020 2020-08-12 11:43:46 create changelog

20200812020021 2020-08-12 11:43:46 first migration

```



### Test the GraphQL Endpoint



Start the server.



```bash

mvnw spring-boot:run

```



Goto the GraphQL Playground - http://localhost:4000/playground.



1. Create some users



   ```graphql

   mutation {

     a: createUser(input: { name: "John" }) {

       id

     }

     b: createUser(input: { name: "Mary" }) {

       id

     }

   }

   ```



   Output:



   ```json

   {

     "data": {

       "a": {

         "id": "94ae9dd3-c739-4c04-8bfb-6a7c94552cd6"

       },

       "b": {

         "id": "2aa8e496-0c9d-41b4-a0c8-467beaf14247"

       }

     }

   }

   ```



2. Query the users



   ```graphql

   query {

     users {

       id

       name

     }

   }

   ```



   Output :



   ```json

   {

     "data": {

       "users": [

         {

           "id": "2aa8e496-0c9d-41b4-a0c8-467beaf14247",

           "name": "Mary"

         },

         {

           "id": "94ae9dd3-c739-4c04-8bfb-6a7c94552cd6",

           "name": "John"

         }

       ]

     }

   }

   ```



3. Delete one of the user by the id



   ```graphql

   mutation {

     deleteUser(id: "94ae9dd3-c739-4c04-8bfb-6a7c94552cd6")

   }

   ```



   Output :



   ```json

   {

     "data": {

       "deleteUser": "94ae9dd3-c739-4c04-8bfb-6a7c94552cd6"

     }

   }

   ```



4. Test the MySQL database



   Run the mysql command using the same docker instance.



   ```bash

   docker exec -it some-mysql mysql -uroot -p"Admin12345"

   ```



   Select the data from user table.



   ```sql

   mysql> use development;

   mysql> select * from user;

   +--------------------------------------+------+----------+

   | id                                   | name | nickName |

   +--------------------------------------+------+----------+

   | 2aa8e496-0c9d-41b4-a0c8-467beaf14247 | Mary | NULL     |

   +--------------------------------------+------+----------+

   ```