java 使用GraphQL-关联对象

GraphQL并不会实现关联查询，数据关联需要程序自己实现

官网首页有介绍获取多个资源只需要一个请求，如想获取用户信息和身份证信息，原来需要先查用户信息，再通过用户id查询身份证信息，而在GraphQL中一次请求就可以实现。

对于这个观点我不敢苟同，可能我还没有体会到这种感觉，我认为只要需求明确，多个资源一次请求在RESTFUl中同样可以实现。

 

 

废话不说了，进入在正题

　　之前已经实现了对user对象的查询操作，现在对user添加一个card属性，操作user对象时可以关联到card信息

User.java

public class User {
private int age;
private long id;
private String name;
private Card card;
public User(int age, long id, String name, Card card) {
this.age = age;
this.id = id;
this.name = name;
this.card = card;
}
public Card getCard() {
return card;
}
public void setCard(Card card) {
this.card = card;
}
public User(int age, long id, String name) {
this.age = age;
this.id = id;
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}

Card.java

public class Card {
private String cardNumber;
private Long userId;
public Card(String cardNumber, Long userId) {
this.cardNumber = cardNumber;
this.userId = userId;
}
public String getCardNumber() {
return cardNumber;
}
public void setCardNumber(String cardNumber) {
this.cardNumber = cardNumber;
}
public Long getUserId() {
return userId;
}
public void setUserId(Long userId) {
this.userId = userId;
}
}

user.graphqls

#对应的User定义如下
schema {
#定义查询
query: UserQuery
}
type UserQuery {
#定义查询类型
user(id:Long) : User
#指定对象以及参数类型
}
type User { #定义对象
id: Long!
#!表示非空
name:String
age:Int
card:Card
}
type Card {
cardNumber:String
userId:Long
}

demo

import clc.bean.Card;
import clc.bean.User;
import graphql.ExecutionResult;
import graphql.GraphQL;
import graphql.schema.GraphQLSchema;
import graphql.schema.idl.RuntimeWiring;
import graphql.schema.idl.SchemaGenerator;
import graphql.schema.idl.SchemaParser;
import graphql.schema.idl.TypeDefinitionRegistry;
import org.apache.commons.io.IOUtils;
/**
* ClassName: GraphQLSDLDemo<br/>
* Description: <br/>
* date: 2019/6/28 11:19 AM<br/>
*
* @author chengluchao
* @since JDK 1.8
*/
public class GraphQLSDLDemo2 {
public static void main(String[] args) throws Exception {
//读取graphqls文件
String fileName = "user.graphqls";
String fileContent = IOUtils.toString(GraphQLSDLDemo2.class.getClassLoader().getResource(fileName), "UTF-8");
//解析文件
TypeDefinitionRegistry typeDefinitionRegistry = new SchemaParser().parse(fileContent);
RuntimeWiring wiring = RuntimeWiring.newRuntimeWiring()
.type("UserQuery", builder ->
builder.dataFetcher("user", environment -> {
Long id = environment.getArgument("id");
Card card = new Card("123456", id);
return new User(18, id, "user0" + id, card);
})
)
.build();
GraphQLSchema graphQLSchema = new SchemaGenerator().makeExecutableSchema(typeDefinitionRegistry, wiring);
GraphQL graphQL = GraphQL.newGraphQL(graphQLSchema).build();
String query = "{user(id:15){id,name,age,card{cardNumber,userId}}}";
ExecutionResult result = graphQL.execute(query);
System.out.println("query: " + query);
System.out.println(result.toSpecification());
}
}

query: {user(id:15){id,name,age,card{cardNumber,userId}}}
{data={user={id=15, name=user015, age=18, card={cardNumber=123456, userId=15}}}}

再次强调，关联信息是程序控制的，并不是GraphQL