usage_customtemplates

Customizing code templates

Code generated by the Graphql Maven Plugin is generated applying a set of Velocity templates to the input GraphQL Schmea. Templates are located in the project at graphql-maven-plugin-logic/src/main/resources/templates

If for any reason you may need to customize the template to modify the generated code, this can be done by using the plugin parameter templates. You can then provide your own templates. There are two possibilities for that:

By putting them in a jar, that will be added as a dependency for the graphql-maven-plugin.
(since v1.13) By putting them in your current project or module, and give a reference to it

You can combine both styles in one pom or gradle.build file.

templates param usage

Provide the custom template as a file within the current project

To do this, you provide the path of the file, relative to the project or module root. You can check this sample:

<project ...>
...

<build>
	<plugins>
...
		<plugin>
			<groupId>com.graphql-java-generator</groupId>
			<artifactId>graphql-maven-plugin</artifactId>
			<version>${lastReleasedVersion}</version>

			<executions>
				<execution>
					<goals>
						<goal>graphql</goal>
					</goals>
				</execution>
			</executions>
			<configuration>
				<mode>client</mode>
				<templates>
					<!-- The SUBSCRIPTION_EXECUTOR is found in this project, int the src/graphql/customtemplates folder -->
					<SUBSCRIPTION_EXECUTOR>src/graphql/customtemplates/custom_client_subscription_executor.vm.java</SUBSCRIPTION_EXECUTOR>
				</templates>
			</configuration>
		</plugin>
	</plugins>
</build>
...
</project>

Provide the custom template within a provided jar

Here there's an example of plugin configuration to use customized templates

<project ...>
...

<build>
	<plugins>
...
		<plugin>
			<groupId>com.graphql-java-generator</groupId>
			<artifactId>graphql-maven-plugin</artifactId>
			<version>${lastReleasedVersion}</version>

			<executions>
				<execution>
					<goals>
						<goal>graphql</goal>
					</goals>
				</execution>
			</executions>
			<configuration>
				<mode>client</mode>
				<templates>
					<!-- The QUERY_MUTATION is found in the dependency, added just below WITHIN the plugin definition -->
					<QUERY_MUTATION>classpath/entry/to/customtemplate.java.vm</QUERY_MUTATION>
				</templates>
			</configuration>
			<dependencies>

				<!-- Dependency containing your templates-->
				<dependency>
					<groupId>...</groupId>
					<artifactId>...</artifactId>
					<version>...</version>
				</dependency>

			</dependencies>
		</plugin>
	</plugins>
</build>
...
</project>

The templates param is a map where the key is the ID of the template to customize and the value is a classpath entry to the resources containing the customized template.

Customize templates shall be provided in a dependency configured in the plugin.

Both client and server templates can be customized.

Template IDs

The available template IDs that can be configured for customization are:

Examples

Available on the project there is an example of this behavior:

graphql-maven-plugin-samples-customtemplates-resttemplate: contains an example of a template customization for QUERY_MUTATION_SUBSCRIPTION template. Code generated uses a Spring implementation of com.graphql_java_generator.client.QueryExecutor that uses RestTemplate as the client
graphql-maven-plugin-samples-customtemplates-client: a Spring-based client generated with the previous customized template.