Spring Boot Maven Netflix DGS GraphQL Codegen + Relay Pagination

A step by step guide to integrate codegen with pagination

Running this specific project

If you have already checked out this repo, you may do a maven clean install and you are good to run it as springboot application. otherwise you may follow the below provided instructions to make one from scratch.

Generating Base Project

Generate a Spring Boot maven java 17 project with dependencies Springweb and Lombok from https://start.spring.io/

IDE Plugins (IntelliJ Idea)

Add Netflix DGS plugins to IDE https://plugins.jetbrains.com/plugin/17852-dgs https://plugins.jetbrains.com/plugin/12465-dgt-codegen Or search it in the IDE marketplace for “DGS” & “DGT-Codegen”

Dependencies

<dependencyManagement>
    <dependencies>
	    <dependency>
		    <groupId>com.netflix.graphql.dgs</groupId>
		    <artifactId>graphql-dgs-platform-dependencies</artifactId>
		    <version>6.0.1</version>
		    <type>pom</type>
		    <scope>import</scope>
	    </dependency>
    </dependencies>
</dependencyManagement>

<dependency>
    <groupId>com.netflix.graphql.dgs</groupId>
    <artifactId>graphql-dgs-spring-boot-starter</artifactId>
</dependency>

<dependency>
    <groupId>com.netflix.graphql.dgs</groupId>
    <artifactId>graphql-dgs-pagination</artifactId>
</dependency>

Schema.graphqls

Add schema file in path “resources/graphql/”. If the path doesn't exist create the graphql folder under the resources folder and place the file.

Make sure the contents of the .graphqls files are correct and without any typos.

Codegen Plugin Configuration

This plugin is built by a community member “deweyjose” and it is a port out from the official Netflix DGS Gradle plugin click here for more info.

<plugin>
    <groupId>io.github.deweyjose</groupId>
    <artifactId>graphqlcodegen-maven-plugin</artifactId>
    <version>1.18</version>
    <executions>
	    <execution>
		    <goals>
			    <goal>generate</goal>
		    </goals>
	    </execution>
    </executions>
    <configuration>
	    <subPackageNameDatafetchers>graph.query</subPackageNameDatafetchers>
	    <subPackageNameTypes>graph.schema</subPackageNameTypes>
	    <schemaPaths>
		    <param>src/main/resources/graphql/schema.graphqls</param>
	    </schemaPaths>
	    <typeMapping>
		    <MessageConnection>graphql.relay.SimpleListConnection&lt;Message&gt;</MessageConnection>
	    </typeMapping>
	    <packageName>com.shamsu.codegenpoc</packageName>
	    <outputDir>${project.build.directory}</outputDir>
    </configuration>
</plugin>

Note: those Types having @connection annotation in the schema file, in configuration we need to put them under <typeMapping></typeMapping> tag as shown above for Type Message.

This ensures that while codegen is running, it will create the relay file in runtime for those 2 Types.

Properties or yml file

Add these properties to yml:

dgs:
	graphql:
		schema-locations:
			- "classpath*:graphql/**/*.graphql*"

Maven command

Run this maven command to generate the files by using codegen:

graphqlcodegen:generate -f pom.xml

Or Go to maven->Plugins->graphqlcodegen->expand and run the maven “graphqlcodegen:generate”

Generated files

After a successful build you can see the generated java files and dataFetchers files created based on schema provided in the resources/ghaphql folder and in the configuration provided in the pom.xml file inside tag <schemaPaths> are generated under the target folder.

For development process one can copy these generated files under src/main/java/com/shamsu/codegenPOC/graph/schema||query||mutation and place DgsConstants.java in the src/main/java/com/shamsu/codegenPOC/ path.

Logic and data layer implementation

Implement the datafetcher files as per the requirement, add DB connections and complete the generated methods present in the Datafetcher files.

Running the project

Run the project as a Spring boot application, it should start a local Tomcat server at port ‘8080’.

Open http://localhost:8080/graphiql and test any desired query.