Question

我在使用graphql中的这种方法添加解析器时遇到问题：

@RestController
@RequestMapping("/api/dictionary/")
@RequiredArgsConstructor(onConstructor = @__(@Autowired))
public class DictionaryController {
    @Value("classpath:items.graphqls")
    private Resource schemaResource;
    private GraphQL graphQL;
    private final DictionaryService dictionaryService;

    @PostConstruct
    public void loadSchema() throws IOException {
        File schemaFile = schemaResource.getFile();
        TypeDefinitionRegistry registry = new SchemaParser().parse(schemaFile);
        RuntimeWiring wiring = buildWiring();
        GraphQLSchema schema = new SchemaGenerator().makeExecutableSchema(registry, wiring);
        graphQL = GraphQL.newGraphQL(schema).build();
    }

private RuntimeWiring buildWiring() {
    DataFetcher<List<DictionaryItemWithParentDto>> fetcher6 = dataFetchingEnvironment -> dictionaryService.getClaimSubType();

        return RuntimeWiring.newRuntimeWiring()
                .type("Query", typeWriting ->
                   typeWriting
                    .dataFetcher("getClaimSubType", fetcher6)
                    )
                .build();
    }


public List<DictionaryItemWithParentDto> getClaimSubType() {
    return dictionaryService.getClaimSubType();
   }
  }

items.graphqls文件内容：

type Query {
    getClaimSubType: [DictionaryItemWithParentDto]
}

type DictionaryItemWithParentDto {
    code: String!
    name: String
    parents: [DictionaryItemDto]
}

type DictionaryItemDto {
    code: String!
    name: String
    description: String
}

在Java中，我有Vehicle接口和两个实现它的类：Airplane和Car。当我添加到架构这一行：

union SearchResult = Airplane | Car

我收到以下错误：

There is no type resolver defined for interface / union 'Vehicle' type, There is no type resolver defined for interface / union 'SearchResult' type]}

我不确定如何处理。

如果相反，我添加：

interface Vehicle {
    maxSpeed: Int
}

type Airplane implements Vehicle {
    maxSpeed: Int
    wingspan: Int
}

type Car implements Vehicle {
    maxSpeed: Int
    licensePlate: String
}

我收到以下错误：

errors=[There is no type resolver defined for interface / union 'Vehicle' type]

如何使用我的方法处理这些错误？还有其他方法可以解决吗？

修改

添加这些代码行可以部分解决此问题：

TypeResolver t =  new TypeResolver() {
    @Override
    public GraphQLObjectType getType(TypeResolutionEnvironment env) {
        Object javaObject = env.getObject();
        if (javaObject instanceof Car) {
            return env.getSchema().getObjectType("Car");
        } else if (javaObject instanceof Airplane) {
            return env.getSchema().getObjectType("Airplane");
        } else {
            return env.getSchema().getObjectType("Car");
        }
    }
};

并向RuntimeWiring构建器添加以下内容：

            .type("Vehicle", typeWriting ->
                    typeWriting
                            .typeResolver(t)
            )


    @PostMapping("getVehicle")
    public ResponseEntity<Object> getVehicleMaxSpeed(@RequestBody String query) 
   {
        ExecutionResult result = graphQL.execute(query);
        return new ResponseEntity<Object>(result, HttpStatus.OK);
    }

询问时：

query {
    getVehicle(maxSpeed: 30) {
        maxSpeed

    }
}

我得到maxSpeed，但是当我添加wingspan时出现错误

Field 'wingspan' in type 'Vehicle' is undefined @ 'getVehicle/wingspan'",

我添加了

getVehicle(maxSpeed: Int): Vehicle

到graphqls文件。我认为多态性可以在这里工作。

Answer 1

添加以下代码行可解决此问题：

TypeResolver t =  new TypeResolver() {
    @Override
    public GraphQLObjectType getType(TypeResolutionEnvironment env) {
        Object javaObject = env.getObject();
        if (javaObject instanceof Car) {
            return env.getSchema().getObjectType("Car");
        } else if (javaObject instanceof Airplane) {
            return env.getSchema().getObjectType("Airplane");
        } else {
            return env.getSchema().getObjectType("Car");
        }
    }
};

并向RuntimeWiring构建器添加以下内容：

            .type("Vehicle", typeWriting ->
                    typeWriting
                            .typeResolver(t)
            )


    @PostMapping("getVehicle")
    public ResponseEntity<Object> getVehicleMaxSpeed(@RequestBody String query) 
   {
        ExecutionResult result = graphQL.execute(query);
        return new ResponseEntity<Object>(result, HttpStatus.OK);
    }

询问时：

query {
    getVehicle(maxSpeed: 30) {
        maxSpeed

    }
}

我得到maxSpeed，但是当我添加wingspan时出现错误

Field 'wingspan' in type 'Vehicle' is undefined @ 'getVehicle/wingspan'",

我添加了

getVehicle(maxSpeed: Int): Vehicle

到graphqls文件。我认为多态性可以在这里工作。

如果我想要子类中的字段，我可以这样询问他们：

query {
    getVehicle(maxSpeed: 10) {
        maxSpeed
        ... on Airplane {
        wingspan
      }
        ... on Car {
        licensePlate
      }
    }
}

Graphql没有为接口/联盟定义的解析器-Java

1 个答案: