데이터 제한

Firebase 컬렉션에는 막대한 양의 데이터가 포함되어 있을 수 있습니다. 범위를 좁혀 필요한 데이터만 가져오면 더 효율적이고 저렴한(클라우드 서비스가 항상 무료인 것은 아님) 응용 프로그램이 될 수 있습니다.

다음 세 가지 방법으로 Collection 객체로 로드되는 데이터의 양을 간단하게 제한할 수 있습니다.

  • 필드 속성을 사용하여 로드하려는 필드를 지정합니다.
  • pageSize 속성을 적당한 수의 레코드로 설정하고 pageOnServer 속성을 true로 설정합니다.
  • queryFilter 속성을 해당 데이터에 적용할 필터를 설명하는 개체로 설정합니다.

이 샘플에서는 이 모든 기술을 보여 줍니다.

import 'bootstrap.css'; import '@grapecity/wijmo.styles/wijmo.css'; import './styles.css'; import { Firestore, Collection } from '@grapecity/wijmo.cloud'; import { ComboBox, CollectionViewNavigator } from '@grapecity/wijmo.input'; import { FlexGrid } from '@grapecity/wijmo.grid'; document.readyState === 'complete' ? init() : window.onload = init; function init() { // create the Firestore data source const API_KEY = 'AIzaSyCvuXEzP57I5CQ9ifZDG2_K8M3nDa1LOPE'; const PROJECT_ID = 'test-9c0be'; const fireStore = new Firestore(PROJECT_ID, API_KEY); // load the Customers collection (selected fields, server-side paging) const countries = 'Brazil,France,Germany,UK,USA'.split(','); const customers = new Collection(fireStore, 'Customers', { sortDescriptions: ['CustomerID'], fields: [ 'CustomerID', 'CompanyName', 'ContactName', 'City', 'Country' ], pageSize: 6, pageOnServer: true }).where('Country', '==', countries[0]); // filter the Collection by country new ComboBox('#cmbCountries', { itemsSource: countries, textChanged: (s, e) => { customers.where('Country', '==', s.text); customers.moveToFirstPage(); } }); // navigate the Collection by page new CollectionViewNavigator('#fsCustomerPager', { cv: customers, byPage: true, headerFormat: 'Page {current:n0}' }); // show the filtered/paged customers new FlexGrid('#fsCustomerGrid', { selectionMode: 'MultiRange', showMarquee: true, isReadOnly: true, autoGenerateColumns: false, columns: customers.fields.map(fld => { return { binding: fld }; }), itemsSource: customers }); }
<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <title>GrapeCity Wijmo Firestore Data Limits</title> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <!-- SystemJS --> <script src="node_modules/systemjs/dist/system.src.js"></script> <script src="systemjs.config.js"></script> <script> System.import('./src/app'); </script> </head> <body> <div class="container-fluid"> <div id="cmbCountries"></div> <div id="fsCustomerPager"></div> <div id="fsCustomerGrid"></div> </div> </body> </html>
.wj-flexgrid { margin: 1em 0; } .wj-combobox { margin-right: 1em; }
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