NEST.JS框架中TypeORM的安装和使用教程

$ node --version
v10.11.0
$ npm --version
6.5.0

$ npm i -g @nestjs/cli
/usr/local/bin/nest -> /usr/local/lib/node_modules/@nestjs/cli/bin/nest.js
+ @nestjs/cli@5.7.1
added 11 packages from 6 contributors, 
removed 27 packages and updated 12 packages in 10.322s

$ nest --version
5.7.1

npm install typeorm reflect-metadata @types/node
# 安装数据库驱动
npm install mysql2  # MySQL
npm install pg     # PostgreSQL

// 统计所有记录
const total = await repository.count();

// 带条件的统计
const completedCount = await repository.count({
  where: { completed: true }
});

// 多个条件
const count = await repository.count({
  where: { 
    status: 'pending',
    userId: 1
  }
});

// 查询所有记录
const allRecords = await repository.find();

// 带条件查询
const pendingRecords = await repository.find({
  where: { status: 'pending' }
});

// 多个条件（AND）
const records = await repository.find({
  where: { 
    status: 'pending',
    userId: 1
  }
});

// 或条件（OR）
const records = await repository.find({
  where: [
    { status: 'pending' },
    { status: 'in-progress' }
  ]
});

const records = await repository.find({
  select: ['id', 'title', 'createdAt'],  // 选择特定字段
  where: { status: 'pending' },
  order: { createdAt: 'DESC' },          // 排序
  skip: 10,                              // 跳过前10条
  take: 20,                              // 取20条
  relations: ['images', 'user']          // 关联查询
});

// 按ID查询
const record = await repository.findOne(1);

// 按条件查询
const record = await repository.findOne({
  where: { title: '特定标题' }
});

// 带关联查询
const record = await repository.findOne({
  where: { id: 1 },
  relations: ['images', 'user'],
  select: ['id', 'title', 'description']
});

// 分页查询，同时返回数据和总数
const [records, totalCount] = await repository.findAndCount({
  where: { status: 'pending' },
  skip: 0,
  take: 10,
  order: { createdAt: 'DESC' }
});

// 返回结果：{ records: [...], total: 100 }

// 方法1：create + save
const newRecord = repository.create({
  title: '新标题',
  description: '描述内容',
  userId: 1
});
await repository.save(newRecord);

// 方法2：直接 save
await repository.save({
  title: '新标题',
  description: '描述内容',
  userId: 1
});

// 批量保存
await repository.save([
  { title: '标题1', userId: 1 },
  { title: '标题2', userId: 1 }
]);

// 按条件更新
await repository.update(
  { status: 'pending' },      // 条件
  { status: 'completed' }     // 更新内容
);

// 按ID更新
await repository.update(1, { 
  title: '新标题',
  completed: true 
});

// 批量更新
await repository.update(
  { userId: 1 },
  { priority: 2 }
);

// 按ID删除
await repository.delete(1);

// 按条件删除
await repository.delete({ 
  status: 'completed' 
});

// 批量删除
await repository.delete([1, 2, 3]);

// 复杂查询
const records = await repository
  .createQueryBuilder('report')
  .leftJoinAndSelect('report.images', 'image')
  .leftJoinAndSelect('report.user', 'user')
  .where('report.status = :status', { status: 'pending' })
  .andWhere('report.userId = :userId', { userId: 1 })
  .orderBy('report.createdAt', 'DESC')
  .skip(0)
  .take(10)
  .getMany();

// 原生SQL查询
const records = await repository
  .createQueryBuilder('report')
  .where('DATE(created_at) = :date', { date: '2024-01-01' })
  .getMany();

// 上报记录的业务查询示例
export class ProblemReportService {
  // 获取用户的上报记录
  async getUserReports(userId: number, page: number = 1, limit: number = 10) {
    const [reports, total] = await this.problemReportRepository.findAndCount({
      where: { userId },
      relations: ['images', 'project'],
      order: { createdAt: 'DESC' },
      skip: (page - 1) * limit,
      take: limit
    });
    
    return {
      reports,
      total,
      page,
      totalPages: Math.ceil(total / limit)
    };
  }

  // 获取项目统计
  async getProjectStats(projectId: number) {
    const total = await this.problemReportRepository.count({
      where: { projectId }
    });
    
    const byStatus = await this.problemReportRepository
      .createQueryBuilder('report')
      .select('report.status, COUNT(*) as count')
      .where('report.projectId = :projectId', { projectId })
      .groupBy('report.status')
      .getRawMany();
    
    return { total, byStatus };
  }

  // 更新上报状态
  async updateReportStatus(id: number, status: number) {
    await this.problemReportRepository.update(id, { status });
    return this.problemReportRepository.findOne(id);
  }
}

// 比较运算符
const records = await repository.find({
  where: {
    priority: MoreThan(2),           // 大于
    createdAt: LessThan(new Date()), // 小于
    userId: In([1, 2, 3]),           // 在数组中
    title: Like('%关键词%')           // 模糊查询
  }
});

// 范围查询
const records = await repository.find({
  where: {
    createdAt: Between(
      new Date('2024-01-01'),
      new Date('2024-01-31')
    )
  }
});