我正在为具有多个关系的现有数据库创建应用程序,如下所示:
表格用户:
Id int主键
表角色:
Id int主键
表UserRoles:
UserId int主键和User.Id的外键
RoleId 完整的Role.Id主键和外键
现在的目标是在LoopBack4中实现多对多关系,而我被困在这一点上,一个模型必须包含至少一个id / pk属性:
到目前为止,我使用以下线程:Loopback 4: Many to Many Relation来构建应用程序。但是在该示例中,关系表中有一个额外的id字段。关键是,由于数据库已经在使用中,我无法更改表,因此我必须使用它。
所以我的代码当前看起来像这样:
user.model.ts
import {Entity, hasMany, model, property} from '@loopback/repository';
import {UserRole} from "./user-role.model";
@model({settings: {}})
export class User extends Entity {
@property({
type: 'number',
id: true,
required: true,
})
Id: number;
// ... all the other properties ...
@hasMany(() => UserRole, {keyTo: 'UserId'})
UserRoles?: UserRole[];
constructor(data?: Partial<User>) {
super(data);
}
}
export interface UserRelations {
// describe navigational properties here
}
export type UserWithRelations = User & UserRelations;
user-role.model.ts
import {belongsTo, Entity, model} from '@loopback/repository';
import {User} from "./user.model";
import {Role} from "./role.model";
@model({
settings: {},
name: 'UserRoles'
})
export class UserRole extends Entity
{
@belongsTo(() => User)
UserId: number;
@belongsTo(() => Role)
RoleId: number;
constructor(data?: Partial<UserRole>)
{
super(data);
}
}
export interface UserRoleRelations
{
// describe navigational properties here
}
export type UserRoleWithRelations = UserRole & UserRoleRelations;
user.repository.ts
import {DefaultCrudRepository, Filter, Getter, HasManyRepositoryFactory, Options, repository} from '@loopback/repository';
import {User, UserRelations, UserRole, UserWithRelations} from '../models';
import {MySqlDataSource} from '../datasources';
import {inject} from '@loopback/core';
import {UserRoleRepository} from "./user-role.repository";
export class UserRepository extends DefaultCrudRepository<User, typeof User.prototype.Id, UserRelations>
{
public readonly UserRoles: HasManyRepositoryFactory<UserRole, typeof UserRole.prototype.UserId>;
constructor(
@inject('datasources.MySQL') dataSource: MySqlDataSource,
@repository.getter('UserRoleRepository') getUserRoleRepository: Getter<UserRoleRepository>)
{
super(User, dataSource);
this.UserRoles = this.createHasManyRepositoryFactoryFor('UserRoles', getUserRoleRepository);
}
async find(filter?: Filter<User>, options?: Options): Promise<UserWithRelations[]>
{
// Prevent juggler for applying "include" filter
// Juggler is not aware of LB4 relations
const include = filter && filter.include;
filter = {...filter, include: undefined};
const result = await super.find(filter, options);
const includeRelations = include ? include.map(x => x.relation) : [];
// poor-mans inclusion resolver, this should be handled by DefaultCrudRepo
// and use `inq` operator to fetch related roles in fewer DB queries
// this is a temporary implementation, please see
// https://github.com/strongloop/loopback-next/issues/3195
if(includeRelations.includes('Roles'))
{
await Promise.all(result.map(async u =>
{
u.UserRoles = await this.UserRoles(u.Id).find();
}));
}
return result;
}
}
我要做什么才能获得分配给用户的角色?据我了解,我需要建立hasMany-Relation。但是环回cli打破了上面的错误,我看不到我现在要做的事情。