Nestjs GraphQL联合类型

Question

我尝试将UnionType与Graphql集成，但是不幸的是没有成功。

我收到错误消息： Either the SearchResult type should provide a \"resolveType\" function or each possible type should provide an \"isTypeOf\" function."

我已经尝试使用解析器内部名为resolveType的ResolveProperty解决该问题。但是该功能未执行。

当我命名函数__resolveType时，我收到错误消息Name "__resolveType" must not begin with "__", which is reserved by GraphQL introspection.

createUnionType函数：

export const SearchResultUnion = createUnionType({
    name: "SearchResult",  // the name of the GraphQL union
    types: [CPublicStore,CArticle, CService], // array of object types classes
});

我的Search-ObjectType：

@ObjectType()
export class CSearch implements ISearch {
    @Field(type => [SearchResultUnion]) source: (CArticle | CService | CPublicStore)[]
    ...
}

和应该解析源属性的解析器：

@Resolver(of => CSearch)
export class SearchTransform implements ResolverInterface<CSearch>{
...
    @ResolveProperty("__resolveType",()=>String)
    __resolveType(obj) {
       ....
    }
}