如何获取类型表多个关系列计数

Question

用户实体

@Entity()
export class User {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  name: string;

  @ManyToMany(type => Product)
  @JoinTable()
  likedProducts: Product[]
}

产品实体

export class Product {
  @PrimaryGeneratedColumn()[enter image description here][1]
  id: number;

  @Column()
  name: string;

  @ManyToMany(type => User)
  likedUsers: User[];
}

我想知道有多少用户喜欢Product Entity的某些产品。

表格图像示例

TableImageExample

我想获取productId为10的列数，在这种情况下，不能移动JoinTable。

我试过了

      const product = await this.products.findOne(id, {
        relations: ['likedUsers'],
      });
      console.log(product.likedUsers.length);

结果

TypeError: Cannot read property 'tablePath' of undefined
    at /Users/apple/Documents/project/monster-backend/src/query-builder/SelectQueryBuilder.ts:1539:76
    at Array.map (<anonymous>)
    at SelectQueryBuilder.createJoinExpression (/Users/apple/Documents/project/monster-backend/src/query-builder/SelectQueryBuilder.ts:1498:57)
    at SelectQueryBuilder.getQuery (/Users/apple/Documents/project/monster-backend/src/query-builder/SelectQueryBuilder.ts:58:21)
    at SelectQueryBuilder.QueryBuilder.getQueryAndParameters (/Users/apple/Documents/project/monster-backend/src/query-builder/QueryBuilder.ts:440:28)
    at SelectQueryBuilder.<anonymous> (/Users/apple/Documents/project/monster-backend/src/query-builder/SelectQueryBuilder.ts:2092:40)
    at step (/Users/apple/Documents/project/monster-backend/node_modules/tslib/tslib.js:143:27)
    at Object.next (/Users/apple/Documents/project/monster-backend/node_modules/tslib/tslib.js:124:57)
    at /Users/apple/Documents/project/monster-backend/node_modules/tslib/tslib.js:117:75
    at new Promise (<anonymous>)

Answer 1

我认为你需要告诉typeorm ManyToMany装饰器中的“关系属性”。像这样：@ManyToMany(type => Product, product => product.likedUsers)

products实体中也是如此。

您可以在the documentation中阅读有关它的更多信息