TypeOrm+Nest.js分页处理（含GROUP BY分组查询）

说明：该代码为已经过测试的生产环境代码
若有所帮助，望君轻轻一点，手有余香

import {
     RpcException } from '@nestjs/microservices';
import {
     EntityManager, getManager, SelectQueryBuilder } from 'typeorm';/** @Author: Horace* @Date: 2019-08-30 14:21:12* @Last Modified by: Horace* @Last Modified time: 2019-08-30 14:21:12*/
export class Pagination {
    // @IsNotEmpty()// @ApiModelProperty({ description: "页码", type: "number", example: 1 })private pageNum: number;// @IsNotEmpty()// @ApiModelProperty({ description: "一页显示条数", type: "number", example: 10 })private pageSize: number;// @ApiModelProperty({ description: "总页数", type: "number", example: 10 })private totalNum: number;// @ApiModelProperty({ description: "总条数", type: "number", example: 10 })private totalRows: number;// @ApiModelProperty({ description: "数据" })public data?: any[];public get _pageNum(): number {
    return this.pageNum;}public set _pageNum(param: number) {
    if (param <= 0) {
    param = 1;}// if (param > this._totalNum) {
    // param = this._totalNum;// }this.pageNum = param;}public get _pageSize() {
    return this.pageSize;}public set _pageSize(param: number) {
    this.pageSize = param;}public get _totalRows() {
    return this.totalRows;}public set _totalRows(param: number) {
    this.totalRows = param;}// @ApiModelProperty({ description: "总页数", type: "number", example: 10 })public get _totalNum