火爆外网的 DGS 框架使用

Netflix 已开放其 Domain Graph Service（DGS）框架的源代码 ，该框架是为了方便整合 GraphQL 使用，用于简化 GraphQL 的实现。

GraphQL 主要是作用于数据接口，比如前端后端交互。无需定义或修改后台 Controller、Service 等业务代码即可实现灵活的数据变更，客户端可以自由获取服务端事先定义好的数据，提高了交互接口的灵活性

组件依赖

• graphql-dgs-spring-boot-starter

<dependency>
    <groupId>com.netflix.graphql.dgs</groupId>
    <artifactId>graphql-dgs-spring-boot-starter</artifactId>
    <version>3.5.1</version>
</dependency>

• DGS 必须从 jcenter 下载,不然部分依赖无法下载。踩坑很久

	<profiles>
		<profile>
			<activation>
				<activeByDefault>true</activeByDefault>
			</activation>
			<repositories>
				<repository>
					<snapshots>
						<enabled>false</enabled>
					</snapshots>
					<id>central</id>
					<name>bintray</name>
					<url>https://jcenter.bintray.com</url>
				</repository>
			</repositories>
			<pluginRepositories>
				<pluginRepository>
					<snapshots>
						<enabled>false</enabled>
					</snapshots>
					<id>central</id>
					<name>bintray-plugins</name>
					<url>https://jcenter.bintray.com</url>
				</pluginRepository>
			</pluginRepositories>
			<id>bintray</id>
		</profile>
	</profiles>

定义接口 schema

• /src/main/resources/schema/schema.graphqls

此文件定义了客户端请求入参格式和查询数据类型

type Query {
    shows(title: String ,releaseYear: Int): [Show]
}

type Show {
    title: String
    releaseYear: Int
}

定义数据抽取规则

@DgsComponent
public class ShowsDatafetcher {

	@DgsData(parentType = "Query", field = "shows")
	public List<Show> shows(@InputArgument("title") String title, @InputArgument("releaseYear") Integer releaseYear) {
		if (title == null) {
			return shows;
		}

		return shows.stream().filter(s -> s.getTitle().contains(title)).collect(Collectors.toList());
	}

    // 模拟 DB 查询
  	private final List<Show> shows = List.of(
			new Show("java", 1995),
			new Show("php", 1995),
			new Show("python", 1990),
			new Show("golang", 2009),
			new Show("rust", 2015)
	);
}

UI 前端调试

• 访问: http://localhost:8080/graphiql

• 条件查询

接口调用

curl --location --request POST 'http://localhost:8080/graphql' \
--header 'Content-Type: application/json' \
--data-raw '{"query":"{\n  shows(title: \"java\", releaseYear: 1995) {\n    title\n    releaseYear\n  }\n}\n","variables":null}'

java 调用

@SpringBootTest(classes = {DgsAutoConfiguration.class, ShowsDatafetcher.class})
class ShowsDatafetcherTests {

	@Autowired
	DgsQueryExecutor dgsQueryExecutor;

	@Test
	void shows() {
		List<String> titles = dgsQueryExecutor.executeAndExtractJsonPath(
				" { shows { title releaseYear }}",
				"data.shows[*].title");
		assertThat(titles).contains("java");
	}
}

本节源码

源码: https://github.com/lltx/dgs-demo

DGS 官网: https://netflix.github.io/dgs

>>> 源码 https://gitee.com/log4j/pig，欢迎署名转载 <<<

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