服务器端分页请求数量有限

时间:2018-06-19 01:13:31

标签: node.js angular express angular5 feathersjs

我的前端是Angular5。后端是REST API NODE.JS,数据库是POSTGRES。

我的postgres中的表命名组织包含100k(100 000)行。

我的表中包含所有组织的列表,其中包含组织名称,位置等信息。

此时我的前端只显示50个组织。我有控制台记录了这个,我的后端只发送50个数组。

我的目标是使用服务器端分页在前端表中显示所有组织(其中10万个)。

已经对显示的当前值进行了分页,其中有50个。代码如下

下面的前端表工作(目前只显示从后端发送的50个组织)

 <div class="card-body">
      <div class="row">

            <div class="table-col">
                <div class="card table">
                    <div class="row header">
                        <div class="col col-md-6">Name</div>
                        <div class="col col-md-2">ID</div>
                        <div class="col col-md-2">Location</div>
                        <div class="col col-md-2">Person in charge</div>
                    </div>
                    <div *ngFor="let group of organizations">
                        <div *ngIf="group.name == 'all'">
                            <div class="row content-row" *ngFor="let organization of group.array |  search: term | orderBy: order | paginate: {itemsPerPage: 13, currentPage:page1, id: '1'}"
                                [routerLink]="['/organization/edit', organization.id]">
                                <div class="col col-md-6">{{organization.name}}</div>
                                <div class="col col-md-2">{{organization.id}}</div>
                                <div class="col col-md-2"  *ngIf="organization.place?.fullName != null">{{organization.place?.fullName}}</div>
                                <div class="col col-md-2"  *ngIf="organization.place?.fullName == null"><span class="badge badge-danger">-- N/A -- </span></div>
                                <div *ngIf="organization.person?.fullname != null" class="col col-md-2">{{organization.person?.fullname}}

                                </div>
                                 <div *ngIf="organization.person?.fullname == null" class="col col-md-2"><span class="badge badge-danger">-- N/A -- </span></div> 


                            </div>
                        </div>
                        <div *ngIf="group.name != 'all'">
                            <div class="row content-row">
                                <div class="col col-md-12 group-name" (click)="toggleGroup(group.name)">{{group.name + ':'}}</div>
                            </div>
                            <div *ngIf="showGroup == group.name">
                                <div class="row content-row" *ngFor="let organization of group.array | search: term |   paginate: {itemsPerPage: 5, currentPage:page2, id: '2'}"
                                    [routerLink]="['/organization/edit', organization.id]">
                                    <div class="col col-md-6" style="padding-left:23px;">{{organization.name}}</div>
                                    <div class="col col-md-2">{{organization.id}}</div>
                                    <div class="col col-md-2">{{organization.place?.fullName}}</div>
                                    <div class="col col-md-2">{{organization.person?.fullname}}
                                    </div>
                                </div>
                            </div>
                        </div>
                    </div>
                    <div *ngIf="!(organizations[0].array.length > 0)" class="row noResults">
                        <label>No results..</label>
                    </div>
                    <div *ngIf="organizations[0].name == 'all'" class="paggination-row">
                        <div class="paggination">
                            <pagination-controls (pageChange)="page1 = $event" id="1" maxSize="5" directionLinks="true" autoHide="true" previousLabel="Previous"
                                nextLabel="Next">
                            </pagination-controls>
                        </div>
                    </div>
                    <div *ngIf="organizations[0].name != 'all' && showGroup != ''" class="paggination-row">
                        <div class="paggination">
                            <pagination-controls (pageChange)="page2 = $event" id="2" maxSize="5" directionLinks="true" autoHide="true" previousLabel="Previous"
                                nextLabel="Next">
                            </pagination-controls>
                        </div>
                    </div>
                </div>
            </div>
        </div>
      </div>

现在在我的配置的后端我有以下代码:

   "host": "0.0.0.0",
      "port": 3030,
      "public": "../public/",
      "paginate": {
          "default": 50,
        "max": 50
      },

注意:主机ip故意改变。 Paginate是我的前线在有10万个值时只接收50个值的原因。

现在,如果我继续讨论并将默认值和最大值更改为100k,我的前端应该显示所有组织,但可能会使客户端和服务器崩溃。

如果我做假的分页,也不会有太大的帮助。

现在我想知道如何继续使用有限的请求,例如50或100(因此我的服务器还活着),但仍然使用服务器端分页或任何必要的内容显示我前端的所有组织。

感谢任何帮助,非常感谢你花时间阅读本文。

edit1:加载所有组织的服务:

import { Injectable } from '@angular/core';
import { Http, Headers } from "@angular/http";
import 'rxjs/add/operator/map';
import { AppSettings } from '../../../../../../app.settings';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';

//service made to comunicate with backend
@Injectable()
export class CreateOrganizacijeService {
    private dataSource = new BehaviorSubject<any>("default")
    currentData = this.dataSource.asObservable();

    constructor(
        private http: Http
    ) { }

    updateData(data) {
        this.dataSource.next(data);
    }

    getAll() {
        let headers = new Headers();
        let token = localStorage.getItem('feathers-jwt');

        headers.append('Content-Type', 'application/json');
        headers.append('Authorization', 'Bearer ' + token)
        return this.http.get(AppSettings.API_ENDPOINT + '/organization', { headers: headers }).map(res => res.json())
    }

    getOne(id) {
        let headers = new Headers();
        let token = localStorage.getItem('feathers-jwt');

        headers.append('Content-Type', 'application/json');
        headers.append('Authorization', 'Bearer ' + token)
        return this.http.get(AppSettings.API_ENDPOINT + '/organization?id=' + id, { headers: headers }).map(res => res.json())
    }

    createNew(organization) {
        let headers = new Headers();
        let token = localStorage.getItem('feathers-jwt');

        headers.append('Content-Type', 'application/json');
        headers.append('Authorization', 'Bearer ' + token)
        return this.http.post(AppSettings.API_ENDPOINT + '/organization', organization, { headers: headers }).map(res => res.json())
    }

    delete(id) {
        let headers = new Headers();
        let token = localStorage.getItem('feathers-jwt');

        headers.append('Content-Type', 'application/json');
        headers.append('Authorization', 'Bearer ' + token)
        return this.http.delete(AppSettings.API_ENDPOINT + '/organization?id=' + id, { headers: headers }).map(res => res.json())
    }

    edit(id, organization) {
        let headers = new Headers();
        let token = localStorage.getItem('feathers-jwt');

        headers.append('Content-Type', 'application/json');
        headers.append('Authorization', 'Bearer ' + token)
        return this.http.patch(AppSettings.API_ENDPOINT + '/organization?id=' + id, organization, { headers: headers }).map(res => res.json())
    }
}

组件ngonit(我加载组织的地方)

  ngOnInit() {

     this.currentUser = JSON.parse(localStorage.getItem('user'));
    if(this.currentUser.roleId == '2') {
      this.isAdmin = true; //check if user is admin
  }
        if(JSON.parse(localStorage.getItem('user')).roleId == '2') {
            this.isAdmin = true; //check if user is admin
        }
        this.organizacijeService.currentData.subscribe(res => {

                this.loadOrgs();

        })



    }

    loadOrgs() {
        this.organizacijeService.getAll().subscribe(res => {
            this.organizations[0].array = res.data;
            console.log(this.organizations[0])
        }, err => {
            this.toast.error('Organization: ' + JSON.parse(err._body).message, 'Failed')
        })
    }

2 个答案:

答案 0 :(得分:1)

您可以通过以50的增量增加$skip query parameterpage.total - 50来加载后续页面。

我要记住,一次显示10万条记录可能仍然会导致前端性能出现问题。

答案 1 :(得分:1)

您可以在禁用了分页的服务器端使用代理服务:

app.use('organizations-unpaginated', {
  find(params){
    const _params = Object.assign({}, params, { paginate: false });
    return app.service('organizations').find(_params);
  }
})

就像Daff所说的那样,您会遇到性能问题,我通常会说渲染100k DOM元素(无论如何几乎都是不可见的)是一种不好的做法。