Server-side operations with Node.js

Learn how to perform server-side operations using Node.js with a complete reference implementation that uses the MySQL database.

This guide is intended as a starting point when learning how to use the Server-side Row Model, as it provides a simple grid implementation that uses limited set of features and grid configurations.

The sample Olympic Medals application is developed using a Node.js server that connects to a MySQL database and will demonstrate how data can be lazy-loaded as required, even when performing group, filter and sort operations when working with large datasets.

The following screenshot shows what the finished application looks like:

The reference implementation covered in this guide is for demonstration purposes only. If you use this in production it comes with no warranty or support.

The source code can be found here: https://github.com/ag-grid/ag-grid-server-side-nodejs-example.

Overview

In this Olympic Medals application, the server endpoint will be hosted using a web server comprised of Node.js running Express.js, that connects to a single MySQL datasource.

An overview of technologies used in this guide is illustrated in the diagram below:

We will now proceed and to install and run the application before going through the implementation details.

Download and Install

Clone the example project using: git clone https://github.com/ag-grid/ag-grid-server-side-nodejs-example.git Navigate into the project directory: cd ag-grid-server-side-nodejs-example Install project dependencies and build project using: yarn install

Database Setup

Download and install the database as per the MySql Download documentation.

Create a database with the name 'sample_data'. Then run the following script to create the table olympic_winners and populate it with data via the mysql command line:

mysql -u root -p -D sample_data < ./data/olympic_winners.sql

That's it. We are now ready to run and explore the application.

Running the application

To run the application execute the following from the command line:

yarn start

Then point your browser to http://localhost:4000/

Client Configuration

In order to keep this sample application as simple as possible, the grid configurations are kept to a minimum. The gridOptions required for our grid are shown below:

// client/index.js const gridOptions = { rowModelType: 'serverSide' columnDefs: [ {field: 'athlete'}, {field: 'country', rowGroup: true, hide: true}, {field: 'sport', rowGroup: true, hide: true}, {field: 'year', filter: 'number', filterParams: {newRowsAction: 'keep'}}, {field: 'gold', aggFunc: 'sum'}, {field: 'silver', aggFunc: 'sum'}, {field: 'bronze', aggFunc: 'sum'}, ], defaultColDef: { sortable: true } }

In the code snippet above, the grid is configured to use the Server-side Row Model by setting: gridOptions.rowModelType = 'serverSide'.

Sorting is enabled via defaultColDef.sortable = true property. A simple number filter is also added to the 'year' column. The example has filterParams.newRowsAction = 'keep' set to ensure that as new data is loaded the applied filters are kept - however since v21 of ag-Grid, newRowsAction defaults to 'keep' for Server Side Row Model so this property no longer needs to be set.

To demonstrate Row Grouping, the 'country' and 'sport' columns have been configured with rowGroup = true. Finally, to ensure the medal values are aggregated up the group hierarchy, the value columns have been set up with an aggregation function: aggFunc='sum'.

Server-side Datasource

In order to fetch data for the Server-side Row Model we must implement the IServerSideDatasource, which contains a single method getRows(params) which accepts request params from the grid.

Successful responses are then passed back to the grid via the params.successCallback(rows, lastRow) as shown below:

// client/index.js const datasource = { getRows(params) { console.log(JSON.stringify(params.request, null, 1)); fetch('./olympicWinners/', { method: 'post', body: JSON.stringify(params.request), headers: {"Content-Type": "application/json; charset=utf-8"} }) .then(httpResponse => httpResponse.json()) .then(response => { params.successCallback(response.rows, response.lastRow); }) .catch(error => { console.error(error); params.failCallback(); }) } }; // register datasource with the grid gridOptions.api.setServerSideDatasource(datasource);

Server Endpoint

Hosting our server endpoint /olympicWinners which accepts json requests is done with the help of the express and body-parser npm packages.

// server/server.js import webpack from 'webpack'; import webpackMiddleware from 'webpack-dev-middleware'; import webpackConfig from '../webpack.config.js'; import express from 'express'; import bodyParser from 'body-parser'; import OlympicWinnersService from './olympicWinnersService'; const app = express(); app.use(webpackMiddleware(webpack(webpackConfig))); app.use(bodyParser.urlencoded({extended: false})); app.use(bodyParser.json()); app.post('/olympicWinners', function (req, res) { OlympicWinnersService.getData(req.body, (rows, lastRow) => { res.json({rows: rows, lastRow: lastRow}); }); }); app.listen(4000, () => { console.log('Started on localhost:4000'); });

Request are delegated to the OlympicWinnersService which contains all the server side application logic. The getData() method queries the MySQL database using the mysql npm package with the SQL returned by buildSql().

// server/olympicWinnersService.js import mysql from 'mysql'; class OlympicWinnersService { getData(request, resultsCallback) { const SQL = this.buildSql(request); connection.query(SQL, (error, results) => { const rowCount = this.getRowCount(request, results); const resultsForPage = this.cutResultsToPageSize(request, results); resultsCallback(resultsForPage, rowCount); }); } buildSql(request) { const selectSql = this.createSelectSql(request); const fromSql = ' FROM sample_data.olympic_winners '; const whereSql = this.createWhereSql(request); const limitSql = this.createLimitSql(request); const orderBySql = this.createOrderBySql(request); const groupBySql = this.createGroupBySql(request); return selectSql + fromSql + whereSql + groupBySql + orderBySql + limitSql; } // helper methods ... }

The buildSql() method uses a number of helper methods to build up sql fragments used in the combined SQL which is returned. The implementation details of these helper methods are be omitted from this guide but can be examined in the project repository.

Conclusion

In this guide we presented a reference implementation for integrating the Server-side Row Model with a Node.js server connected to a MySQL database. This included all necessary configuration and install instructions.

A high level overview was given to illustrate the problem this approach solves before providing details of how to achieve the following server-side operations:

  • Sorting
  • Filtering
  • Grouping
  • Aggregation