TypeORM自定义多对多关联无法完整加载关联数据求助

我在Business与Salesperson之间通过中间表BusinessSalesperson创建了自定义多对多关联，相关代码如下：

// Business 实体
@OneToMany(() => BusinessSalesperson, (bsp) => bsp.business, {
    nullable: false,
    onDelete: 'CASCADE',
})
salespersons: Salesperson[]

// Salesperson 实体
@OneToMany(() => BusinessSalesperson, (bsp) => bsp.salesperson, {
    nullable: false,
    onDelete: 'CASCADE',
})
business: Business[]

// BusinessSalesperson 实体
@ManyToOne(() => Salesperson, (sp) => sp.business, {
    eager: true,
    nullable: false,
    onDelete: 'CASCADE',
})
@JoinColumn({ name: 'salespersonid' })
salesperson: Salesperson

@ManyToOne(() => Business, (b) => b.salespersons, {
    eager: true,
    nullable: false,
    onDelete: 'CASCADE',
})
@JoinColumn({ name: 'businessid' })
business: Business;

在服务中执行以下查询语句：

const businesses = this.dataSource.createEntityManager().find(Business, {relations: {salespersons: true, businessSalespersons: { salesperson: true} } });

原本期望获取完整的关联数据，但返回的Business对象中，Salesperson字段为null，具体结果如下：

Business {
    businessid: 1365991,
    companyLegalName: 'SCG',
    businessName: 'SCG',
    salespersons: [
        BusinessSalesperson {
            salespersonId: 549,
            businessId: 1365991,
            administrator: false,
            salesperson: null,
            business: [Business]
        }
    ],
    businessSalespersons: [
        BusinessSalesperson {
            salespersonId: 549,
            businessId: 1365991,
            administrator: false,
            salesperson: null,
            business: [Business]
        }
    ]
}

请问我哪里配置出错了？

1. 实体关联字段类型不匹配 #

Business类中，@OneToMany注解指向的是中间表BusinessSalesperson实体，因此salespersons字段的类型应该是BusinessSalesperson[]，而非Salesperson[]；同理，Salesperson类中，@OneToMany注解指向的也是BusinessSalesperson实体，关联字段的类型必须是BusinessSalesperson[]，不能直接设为Business[]。类型不匹配会导致TypeORM无法正确映射关联关系，进而导致关联数据无法加载。

修正后的实体代码：

// Business 实体
@OneToMany(() => BusinessSalesperson, (bsp) => bsp.business, {
    nullable: false,
    onDelete: 'CASCADE',
})
salespersons: BusinessSalesperson[] // 修正为中间表实体数组

// Salesperson 实体
@OneToMany(() => BusinessSalesperson, (bsp) => bsp.salesperson, {
    nullable: false,
    onDelete: 'CASCADE',
})
businessSalespersons: BusinessSalesperson[] // 修正字段名（语义更清晰）及类型

2. 中间表反向关联指向错误 #

BusinessSalesperson实体中，@ManyToOne的第二个参数需要对应到关联实体中定义的@OneToMany字段。比如Salesperson实体的关联字段现在是businessSalespersons，那么中间表中对应Salesperson的关联需要调整指向：

// BusinessSalesperson 实体中对应Salesperson的关联
@ManyToOne(() => Salesperson, (sp) => sp.businessSalespersons, {
    eager: true,
    nullable: false,
    onDelete: 'CASCADE',
})
@JoinColumn({ name: 'salespersonid' })
salesperson: Salesperson

3. 查询关联配置错误 #

原查询中businessSalespersons并非Business实体的字段，应该使用修正后的salespersons字段，并正确嵌套关联以加载Salesperson数据：

const businesses = this.dataSource.createEntityManager().find(Business, {
    relations: {
        salespersons: { salesperson: true }
    }
});

内容的提问来源于stack exchange，提问作者Simon