带有打字稿的graphql - @FieldResolver 在compiled-to-js type-graphql 中不起作用答案

【问题标题】：graphql with typescript - @FieldResolver not working in compiled-to-js type-graphql带有打字稿的graphql - @FieldResolver 在compiled-to-js type-graphql 中不起作用
【发布时间】：2021-01-01 15:11:08
【问题描述】：

我是 type-graphql 的新手，我遇到了字段解析器无法正常工作的奇怪问题。

我正在使用一堆：

打字稿(3.9.5)
type-graphql(1.0.0)
typeorm(0.2.25)
阿波罗(2.16.0)。

每当我运行我的打字稿（使用 ts-node）时，一切正常，但是当我将编译后的 js 版本与 express 一起使用时，查询仅适用于简单的 db 字段，但 fieldResolvers 根本不起作用，最后我得到“不能为不可为空的字段返回 null”。有趣的是，字段解析器是同一个 @Resolver 类中查询解析器的兄弟。查询被触发（放置控制台日志），但字段解析器从不这样做。有人知道吗？

以下是代码中的一些 sn-ps：

@Entity()
@ObjectType()
export class Member extends BaseEntity {
  @Field(() => ID)
  @PrimaryGeneratedColumn()
  id: string;

  @UseForSearch()
  @UseAsTitle()
  @Field(() => String)
  @IsEmail()
  @Column({ type: 'varchar', unique: true })
  email: string;

  @Field(() => [Item])
  @OneToMany(type => Item, item => item.member)
  items?: Item[];

  @OneToMany(type => Review, review => review.member)
  reviews?: Review[];

  @Field(() => Number)
  itemsCount: number;
}

@Entity()
@ObjectType()
export class Item extends BaseEntity {
  @Field(() => ID)
  @PrimaryGeneratedColumn()
  id: string;

  @ManyToOne(type => Category, category => category.items)
  @JoinColumn({ name: 'categoryId' })
  @Field(() => Category)
  category?: Category;

  @Field(() => String, { nullable: true })
  @Column({
    nullable: true,
  })
  name: string;

  @ManyToOne(type => Member, member => member.items)
  @JoinColumn({ name: 'memberId' })
  @Field(() => Member)
  member?: Member;

  @Field(() => ID)
  @Column('int', { nullable: true })
  public memberId: number | null;
}

import { Resolver, Query, FieldResolver, Root, Ctx, Arg } from 'type-graphql';
import { getRepository, Repository } from 'typeorm';
import { Item } from '../entity';
import { Member } from '../entity/member';

@Resolver(of => Member)
export class MemberResolver {
  constructor(private itemsRepository: Repository<Item>) {
    this.itemsRepository = getRepository(Item);
  }

  @Query(() => [Member])
  members() {
    console.log('in members query');
    return Member.find();
  }

  @FieldResolver()
  async items(@Root() member: Member) {
    return await this.itemsRepository.find({ where: { memberId: member.id } });
  }

  @FieldResolver()
  async itemsCount(@Root() member: Member) {
    console.log('in itemsCount resolver');
    return this.itemsRepository.count({ where: { memberId: member.id } });
  }

query {
  members {
    email
    itemsCount
  }
}

{
  "errors": [
    {
      "message": "Cannot return null for non-nullable field Member.itemsCount.",
      "locations": [
        {
          "line": 4,
          "column": 5
        }
      ],
      "path": [
        "members",
        0,
        "itemsCount"
      ],
      "extensions": {
        "code": "INTERNAL_SERVER_ERROR",
        "exception": {
          "stacktrace": [
            "Error: Cannot return null for non-nullable field Member.itemsCount.",
            "    at completeValue (/Users/admin/tackar/clampa/clampa-server/node_modules/graphql/execution/execute.js:599:13)",
            "    at completeValueCatchingError (/Users/admin/tackar/clampa/clampa-server/node_modules/graphql/execution/execute.js:534:19)",
            "    at resolveField (/Users/admin/tackar/clampa/clampa-server/node_modules/graphql/execution/execute.js:465:10)",
            "    at executeFields (/Users/admin/tackar/clampa/clampa-server/node_modules/graphql/execution/execute.js:297:18)",
            "    at collectAndExecuteSubfields (/Users/admin/tackar/clampa/clampa-server/node_modules/graphql/execution/execute.js:752:10)",
            "    at completeObjectValue (/Users/admin/tackar/clampa/clampa-server/node_modules/graphql/execution/execute.js:742:10)",
            "    at completeValue (/Users/admin/tackar/clampa/clampa-server/node_modules/graphql/execution/execute.js:630:12)",
            "    at completeValue (/Users/admin/tackar/clampa/clampa-server/node_modules/graphql/execution/execute.js:596:21)",
            "    at completeValueCatchingError (/Users/admin/tackar/clampa/clampa-server/node_modules/graphql/execution/execute.js:534:19)",
            "    at /Users/admin/tackar/clampa/clampa-server/node_modules/graphql/execution/execute.js:655:25"
          ]
        }
      }
    }
  ],
  "data": null
}

【问题讨论】：

标签： graphql typeorm typegraphql

【解决方案1】：

您的编译步骤（TS 到 JS）存在问题 - 如果它不发出 ES6 类和箭头函数，它会将 of => Member 视为具有原型的函数，因此它会认为它是对象类型类.

【讨论】：

【解决方案2】：

问题不在于编译。问题是你的数据

您看到的消息是Cannot return null for non-nullable field Member.itemsCount

好吧，要么在 itemsCount 中添加一个值，要么将该字段标记为可为空。问题是您在调用成员计数之前错过了等待

只需添加等待

 @FieldResolver()
  async itemsCount(@Root() member: Member) {
    console.log('in itemsCount resolver');
    return await this.itemsRepository.count({ where: { memberId: member.id } });
  }

【讨论】：