A datagrid enables you to display and edit data. This is vital in many data-driven or line of business applications. I've used it in some of the applications I've built. You might have implemented this in your React app and would have used libraries like react-bootstrap-table, react-grid, or react-table. With those, you can add a Datagrid to your React app, but what if you want the changes to be done in real-time and updates synchronised across connected devices/browsers?

In this article, I will show you how to build a real-time datagrid in React using react-table and Hamoni Sync. react-table is a lightweight and fast library for rendering tables in React, and it supports pagination and many more features. Hamoni Sync is a real-time state synchronisation service which enables you to synchronise your application state in real-time. I will show you how to build a datagrid with people's first and last names.

If you want to follow along you should have some knowledge of React and the following installed:

1. NodeJS
2. npm & npx. If you have installed npm version 5.2.0 or greater, it installs npx alongside npm.
3. create-react-app

Create the React app

We will create a new React project using create-react-app. Open the command line and run npx create-react-app realtime-react-datatable. This will bootstrap a React application for us by creating a new directory realtime-react-datatable with the files needed to build a React application.

With the React app created, we need to install react-table and Hamoni Sync. Still on the command line, run cd realtime-react-datatable to switch to the directory for the app. Run npm i react-table hamoni-sync in the command line to install both packages.

Render the Datagrid

To render the datagrid, we will use the react-table component. Open the file src/App.js and update it with the code below:

import React, { Component } from "react";
import logo from "./logo.svg";
import "./App.css";
// Import React Table
import ReactTable from "react-table";
import "react-table/react-table.css";
// Import Hamoni Sync
import Hamoni from "hamoni-sync";

class App extends Component {
  constructor() {
    super();
    this.state = {
      data: [],
      firstName: "",
      lastName: ""
    };
  }

  handleChange = event => {
    if (event.target.name === "firstName")
      this.setState({ firstName: event.target.value });
    if (event.target.name === "lastName")
      this.setState({ lastName: event.target.value });
  };

  handleSubmit = event => {
    event.preventDefault();
  };

  renderEditable = cellInfo => {
    return (
      <div
        style={{ backgroundColor: "#fafafa" }}
        contentEditable
        suppressContentEditableWarning
        onBlur={e => {
          const data = [...this.state.data];
          data[cellInfo.index][cellInfo.column.id] = e.target.innerHTML;
          this.setState({ data });
        }}
        dangerouslySetInnerHTML={{
          __html: this.state.data[cellInfo.index][cellInfo.column.id]
        }}
      />
    );
  };

  render() {
    const { data } = this.state;

    return (
      <div className="App">
        <header className="App-header">
          <img src={logo} className="App-logo" alt="logo" />
          <h1 className="App-title">Welcome to React</h1>
        </header>
        <p className="App-intro">
          <form onSubmit={this.handleSubmit}>
            <h3>Add new record</h3>
            <label>
              FirstName:
              <input
                type="text"
                name="firstName"
                value={this.state.firstName}
                onChange={this.handleChange}
              />
            </label>{" "}
            <label>
              LastName:
              <input
                type="text"
                name="lastName"
                value={this.state.lastName}
                onChange={this.handleChange}
              />
            </label> 
            
            <input type="submit" value="Add" />
          </form>
        </p>
        <div>
          <ReactTable
            data={data}
            columns={[
              {
                Header: "First Name",
                accessor: "firstName",
                Cell: this.renderEditable
              },
              {
                Header: "Last Name",
                accessor: "lastName",
                Cell: this.renderEditable
              },
              {
                Header: "Full Name",
                id: "full",
                accessor: d => (
                  <div
                    dangerouslySetInnerHTML={{
                      __html: d.firstName + " " + d.lastName
                    }}
                  />
                )
              }
            ]}
            defaultPageSize={10}
            className="-striped -highlight"
          />
        </div>
      </div>
    );
  }
}

export default App;

The code above renders a form and an editable react-table component. <ReactTable /> renders a component with data, columns, and defaultPageSize props. The data props holds the data to display, and columns props for the column definition. The accessor property in columns props indicates the property that holds the value to be displayed for that column. Cell: this.renderEditable property in columns props tells react-table that the column is editable. The other functions (handleSubmit & handleChange) allows getting new data entry from the form on the page.

Add Hamoni Sync

The data for the datagrid will be retrieved and updated in real-time using Hamoni Sync. We already imported the Hamoni library on line 18 in App.js;

import Hamoni from "hamoni-sync";

We need to initialise it and connect to Hamoni server. To do this we need an account and application ID. Follow these steps to create an application in Hamoni.

1. Register and login to Hamoni dashboard
2. Enter your preferred application name in the text field and click the create button. This should create the app and display it in the application list section.
3. Expand the Account ID card to get your account ID

Add the following code to App.js to initialise and connect to Hamoni Sync server.

componentDidMount() {
   const accountId = "YOUR_ACCOUNT_ID";
  const appId = "YOUR_APP_ID";
  let hamoni;

  fetch("https://api.sync.hamoni.tech/v1/token", {
    method: "POST",
    headers: {
    "Content-Type": "application/json; charset=utf-8"
    },
    body: JSON.stringify({ accountId, appId })
  }).then(token => {
    hamoni = new Hamoni(token);

    hamoni
    .connect()
    .then(() => {
      
    })
    .catch(error => console.log(error));
  });
}

The code above will connect the client device or browser to Hamoni Sync server. Copy your account and application ID from the dashboard and replace them with the string placeholder respectively. It's recommended calling the Sync token server from your backend and sending the response token to the client application. For this example, I kept them all in one place.

Add the following to the function in the then() block, to be executed when it successfully connects to the server:

hamoni
    .get("datagrid")
    .then(listPrimitive => {
      this.listPrimitive = listPrimitive;

      this.setState({
        data: [...listPrimitive.getAll()]
      });

      listPrimitive.onItemAdded(item => {
        this.setState({ data: [...this.state.data, item.value] });
      });

      listPrimitive.onItemUpdated(item => {
        let data = [
        ...this.state.data.slice(0, item.index),
        item.value,
        ...this.state.data.slice(item.index + 1)
        ];

        this.setState({ data: data });
      });

      listPrimitive.onSync(data => {
        this.setState({ data: data });
      });
    })
    .catch(console.log);

The code above calls hamoni.get("datagrid") to get the data, with datagrid as the name of the application state on Hamoni Sync. Hamoni Sync allows you to store 3 kinds of state referred to as Sync primitives. They are:

1. Value Primitive: This kind of state holds simple information represented with datatypes like string, boolean or numbers. It is best suited for cases such as unread message count, toggles, etc.

2. Object Primitive: Object state represents states that can be modelled as a JavaScript object. An example usage could be storing the score of a game.

3. List Primitive: This holds a list of state objects. A state object is a JavaScript object. You can update an item based on its index in the list.

If the state is available it resolves and returns a promise with the state primitive object. This object gives us access to methods to update state and get state updates in real-time.

On line 36 we used the getAll() method to get data and set the state for the React component. Also, the methods onItemAdded() and onItemUpdated() are used to get updates when an item is added or updated. The onSync() method is useful in a scenario where a device or browser loses connection, and when it reconnects, it tries to get the latest state from the server and update the local state if there's any.

Add & Update items

From the previous section, we are able to get the data for the datagrid and update the state when an item is added or update. Let's add code to add new items and update an item when a column has been edited. Add the following code to the handleSubmit method:

handleSubmit = event => {
    this.listPrimitive.add({
        firstName: this.state.firstName,
        lastName: this.state.lastName
    });
    this.setState({ firstName: "", lastName: "" });
    event.preventDefault();
};

This code gets the first and last name from the form and adds it to the list state primitive on Hamoni Sync by calling the add() method. This will trigger the onItemAdded() method.

In order to update items as they get edited in the datagrid, we will update the function passed to the onBlur props on line 84 as follows:

onBlur={e => {
    let row = this.state.data[cellInfo.index];
    row[cellInfo.column.id] = e.target.innerHTML;
    this.listPrimitive.update(cellInfo.index, row);
}}

This code updates the item at the index retrieved from the cellInfo object. To update a list state primitive in Hamoni Sync, you call the update() method with the index of the item and the value to update. The renderEditable method should now look like this after the last change:

  renderEditable = cellInfo => {
    return (
      <div
        style={{ backgroundColor: "#fafafa" }}
        contentEditable
        suppressContentEditableWarning
        onBlur={e => {
          let row = this.state.data[cellInfo.index];
          row[cellInfo.column.id] = e.target.innerHTML;
          this.listPrimitive.update(cellInfo.index, row);
        }}
        dangerouslySetInnerHTML={{
          __html: this.state.data[cellInfo.index][cellInfo.column.id]
        }}
      />
    );
  };

At this point we have almost all that's needed to run the app except the initial data that will be rendered on the datagrid. We need to create the state and give it some data on Hamoni Sync. Add a new file seed.js at the root of your working directory and add to it the following code:

const Hamoni = require("hamoni-sync");

let hamoni = new Hamoni("AccountID", "APP_ID");

hamoni
  .connect()
  .then(response => {
    hamoni
      .createList("datagrid", [
        { firstName: "James", lastName: "Darwin" },
        { firstName: "Jimmy", lastName: "August" }
      ])
      .then(() => console.log("create success"))
      .catch(console.log);
  })
  .catch(console.log);

This will create a list primitive state on Hamoni Sync, with a name of datagrid. Replace the AccountID and APP_ID string with your account and application ID. Open the command line and run node seed.js. This should succeed and print out create success message.

Now we can start the React app and see our app in action! Run the command npm start in the command line and it'll open the application in your default browser.

Hooray! We have a real-time editable datagrid with pagination!

Conclusion

We have built a real-time datagrid in React using react-table and Hamoni Sync. With react-table powering the datagrid and Hamoni Sync handling the state for the datagrid. This was all achieved in few lines of code and less effort designing real-time state logic. You can get the finished app of what we built on GitHub. It's possible to track which cell is being edited or lock the cells currently being edited by another user. I'll leave that as a weekend hack for you.

Feel free to leave a comment if anything is not clear or encounter problems while trying to add lock or highlight cells being edited.

Happy coding 🎉