Bind Live Google Cloud Storage Data in Wijmo FlexGrid with CData API Server

With CData API Server, easily create OData endpoints for live Google Cloud Storage data and seamlessly connect and bind them to Wijmo's FlexGrid for real-time, interactive data access without manual data movement.

Wijmo FlexGrid is a lightweight, high-performance JavaScript datagrid for creating responsive, interactive data applications.

With the CData API Server and the Google Cloud Storage Connector (or any of the 350+ available connectors), you can quickly create APIs that expose live data from multiple sources, using industry standards like OData and Swagger for seamless integration with client-side and server-side controls in Wijmo's FlexGrid.

In this article, we'll use the Wijmo FlexGrid JavaScript components to build a simple HTML page that lets you select tables and columns from Google Cloud Storage and display the data.

Let's get started!

Prerequisites

CData API Server: Download a free trial here.
Wijmo FlexGrid: No downloads are required for this example, but you can sign up for a free trial here.
An active Google Cloud Storage account with access to your data.

Overview

Here's a quick overview of the steps we'll follow:

Install the CData API Server, configure a connection to Google Cloud Storage, and expose OData endpoints.
Bind Wijmo Grid to the live OData feed for real-time data access and interaction.

Step 1: Install the CData API Server and Add a Connection to Google Cloud Storage

1.1 Install the API Server

If you haven't already, download an installer for your machine from the CData API Server page. Follow the installation instructions to complete the setup.

Once installed, you can start the server in the following ways:

Windows: CData API Server runs as a service by default. Make sure the service is running, then open http://hostname:port (e.g., http://localhost:8080/) in your browser to access the API Server admin console.
Linux/Mac: You can run the server manually or as a service. To start it manually, navigate to the installation directory and run java -jar apiserver.jar.
Alternatively, run service.sh with root privileges to set up API Server as a Linux system service.

1.2 Enable CORS

When your Wijmo Grid application and the CData API Server are hosted on different domains, CORS (Cross-Origin Resource Sharing) must be enabled. To enable CORS in the API Server:

Go to Settings and click the icon to edit CORS settings.
Enable Cross-Origin Resource Sharing (CORS).
Enable Allow all domains without '*' to accept any origin.
In Access-Control-Allow-Origin, enter your Google Cloud Storage origin domain, or use * to allow all domains (suitable for public APIs).
Enable Access-Control-Allow-Credentials to allow cookies and auth headers.
In Access-Control-Allow-Methods, enter GET, PUT, POST, OPTIONS.
In Access-Control-Allow-Headers, enter Authorization, Content-Type.
Set Access-Control-Max-Age (default: 3600 seconds).
Click Save.

Enabling CORS Settings in the CData API Server

1.3 Add a Google Cloud Storage Connection in the API Server

Go to Settings and click Add Connection in the top-right.
Select Google Cloud Storage. If it's not visible, toggle off Only Installed to view all connectors.
Click Install Connector to auto-install. For a manual setup, choose Manual Install and upload the obtained ZIP file.
Once installed, click Google Cloud Storage to configure connection settings.

Authenticate with a User Account

You can connect without setting any connection properties for your user credentials. After setting InitiateOAuth to GETANDREFRESH, you are ready to connect.

When you connect, the Google Cloud Storage OAuth endpoint opens in your default browser. Log in and grant permissions, then the OAuth process completes

Authenticate with a Service Account

Service accounts have silent authentication, without user authentication in the browser. You can also use a service account to delegate enterprise-wide access scopes.

You need to create an OAuth application in this flow. See the Help documentation for more information. After setting the following connection properties, you are ready to connect:

InitiateOAuth: Set this to GETANDREFRESH.
OAuthJWTCertType: Set this to "PFXFILE".
OAuthJWTCert: Set this to the path to the .p12 file you generated.
OAuthJWTCertPassword: Set this to the password of the .p12 file.
OAuthJWTCertSubject: Set this to "*" to pick the first certificate in the certificate store.
OAuthJWTIssuer: In the service accounts section, click Manage Service Accounts and set this field to the email address displayed in the service account Id field.
OAuthJWTSubject: Set this to your enterprise Id if your subject type is set to "enterprise" or your app user Id if your subject type is set to "user".
ProjectId: Set this to the Id of the project you want to connect to.

The OAuth flow for a service account then completes.

Click Save & Test to validate and complete the connection setup.

Adding a Connection in the CData API Server

1.4 Add and Configure Users

To allow secure access to the created OData endpoints, create and configure Users in the API Server.

Go to Users from the navigation pane, then click Add User.
Set a Username and Password.
Select a Role: Select Admin for full access and Query for limited access.
Define user Privileges (GET, POST, PUT, DELETE, etc.).
Click Add User to save.

Once a user is added, an Authtoken is automatically generated. This token can be used in API requests as a secure authentication method instead of a password.

You can also refresh the Authtoken, disable it, or set expiration rules (e.g., number of days until expiry) by enabling the Token Expiration option in the user settings.

'Authtoken' Settings for the Added User in CData API Server

1.5 Add Tables for the Endpoint

To make data from Google Cloud Storage accessible in Wijmo Grid via OData, you need to expose your desired tables through the API Server. Here's how:

In the API Server, go to API and click Add Table.
Select the Google Cloud Storage connection and click Next.
Choose the tables you want to expose and click Confirm.

Adding Tables for API Endpoint in CData API Server

1.6 Access the Endpoints in Wijmo FlexGrid

Now that your API is configured, Wijmo FlexGrid can connect to the OData endpoints to display live data. Below are the URL formats for OData endpoints that you can use:

Endpoint		URL
Entity List		http://`address`:`port`/api.rsc/
Table Metadata (e.g., albums)		http://`address`:`port`/api.rsc/albums/$metadata?@json
Table Data (e.g., albums)		http://`address`:`port`/api.rsc/albums

These OData endpoints are now ready to be directly consumed in Wijmo FlexGrid using the URL. Since Wijmo FlexGrid supports OData, you can easily bind live data from Google Cloud Storage and create dynamic, interactive grids.

The CData API Server supports full OData filtering capabilities. For custom queries and filtered visualizations, you can append standard OData query parameters like $select, $filter, $orderby, $top, and $skip to your requests.

Step 2: Build the Simple Wijmo Grid

You've got the CData API Server up and running now with consumable OData endpoints from your Google Cloud Storage data. Now let's build a simple Wijmo FlexGrid that lets you select tables and columns and view your data.

Get the CData API Endpoint URL by logging into your CData API Server. Go to API from the left navigation, then click View Endpoints at the top-right.
Copy the URL (e.g., http://localhost:8080/api.rsc).

Getting the API Endpoint URL from CData API Server

Create a new HTML file and give it a name (e.g., Wijmo-Grid.html).
Paste the following code into your HTML file.
Update the following placeholder values at the start of the script section:

yourUsername: Replace with your CData API Server username.
yourPassword: Replace with your CData API Server password.
Your_CData_API_Server_URL: Replace with the full API endpoint URL you copied earlier.


<!DOCTYPE html>
<html lang="en">
<head>

  <meta charset="UTF-8">
  <title>Wijmo Grid with CData API Server</title>

  <!-- Wijmo styles -->
  <link href="https://cdn.mescius.com/wijmo/5.latest/styles/wijmo.min.css" rel="stylesheet" />

  <!-- Wijmo core and controls -->
  <script src="https://cdn.mescius.com/wijmo/5.latest/controls/wijmo.min.js"></script>
  <script src="https://cdn.mescius.com/wijmo/5.latest/controls/wijmo.grid.min.js"></script>
  <script src="https://cdn.mescius.com/wijmo/5.latest/controls/wijmo.input.min.js"></script>
  <script src="https://cdn.mescius.com/wijmo/5.latest/controls/wijmo.odata.min.js"></script>

<style>
    body {
      font-family: Arial, sans-serif;
      margin: 20px;
    }
    h1 {
      color: #00A0FF;
      text-align: center;
    }
    #selectors {
      display: flex;
      flex-wrap: wrap;
      gap: 15px;
      justify-content: center;
      align-items: flex-start;
      margin-bottom: 20px;
    }
    .select-group {
      display: flex;
      flex-direction: column;
      min-width: 200px;
    }
    label {
      font-weight: bold;
      margin-bottom: 5px;
      color: #00A0FF;
    }
    select, button {
      padding: 6px;
      font-size: 14px;
      border: 1px solid #00A0FF;
      border-radius: 4px;
    }
    button {
      background: #00A0FF;
      color: white;
      cursor: pointer;
      height: 40px;
      margin-top: 24px;
    }
    #columnsContainer {
      display: flex;
      flex-direction: column;
      gap: 5px;
      max-height: 150px;
      overflow-y: auto;
      border: 1px solid #00A0FF;
      padding: 8px;
      border-radius: 4px;
    }
    #theGrid {
      margin-top: 20px;
      border: 2px solid #00A0FF;
      height: 500px;
    }
    .wj-header {
      background: #00A0FF !important;
      color: white !important;
      font-weight: bold;
    }
  </style>

</head>
<body>

<h1>Simple Wijmo Grid with CData API Server</h1>

  <div id="selectors">
    <div class="select-group">
      <label for="tableSelect">Select Table</label>
      <select id="tableSelect"></select>
    </div>

    <div class="select-group">
      <label>Select Columns</label>
      <div id="columnsContainer"></div>
    </div>

    <div>
      <button onclick="loadGrid()">Load Grid</button>
    </div>
  </div>

  <div id="theGrid"></div>

<script>
    const username = 'yourUsername';
    const password = 'yourPassword';
    const authHeader = 'Basic ' + btoa(username + ':' + password);
    const serviceUrl = 'Your_CData_API_Server_URL';

    fetch(serviceUrl + '/$metadata', { headers: { Authorization: authHeader } })
      .then(res => res.text())
      .then(text => {
        const parser = new DOMParser();
        const xml = parser.parseFromString(text, 'application/xml');
        const tables = [...xml.getElementsByTagName('EntityType')];
        const select = document.getElementById('tableSelect');
        tables.forEach(t => {
          const name = t.getAttribute('Name');
          const option = document.createElement('option');
          option.value = name;
          option.textContent = name;
          select.appendChild(option);
        });
        loadColumns(); // load columns for the first table
      });

    document.getElementById('tableSelect').addEventListener('change', loadColumns);

    function loadColumns() {
      const table = document.getElementById('tableSelect').value;
      fetch(serviceUrl + '/$metadata', { headers: { Authorization: authHeader } })
        .then(res => res.text())
        .then(text => {
          const parser = new DOMParser();
          const xml = parser.parseFromString(text, 'application/xml');
          const entity = [...xml.getElementsByTagName('EntityType')].find(t => t.getAttribute('Name') === table);
          const columns = [...entity.getElementsByTagName('Property')];
          const container = document.getElementById('columnsContainer');
          container.innerHTML = '';
          columns.forEach(col => {
            const name = col.getAttribute('Name');
            const div = document.createElement('div');
            div.innerHTML = `<label><input type="checkbox" value="${name}" checked> ${name}</label>`;
            container.appendChild(div);
          });
        });
    }

    function loadGrid() {
      const table = document.getElementById('tableSelect').value;
      const selectedCols = [...document.querySelectorAll('#columnsContainer input:checked')].map(i => i.value);

      const odata = new wijmo.odata.ODataCollectionView(serviceUrl, table, {
        requestHeaders: { Authorization: authHeader }
      });

      const grid = new wijmo.grid.FlexGrid('#theGrid', {
        itemsSource: odata,
        autoGenerateColumns: false,
        columns: selectedCols.map(col => ({ binding: col, header: col })),
        selectionMode: 'CellRange',
        allowSorting: true
      });
    }
</script>

</body>
</html>

Open the HTML file in your browser.
Your browser should display the Wijmo FlexGrid. You can select a table and columns to display your data.

Simple Wijmo FlexGrid Displaying API Data

It's that simple. You can build even more complex applications and grids with Wijmo FlexGrid and the CData API Server by connecting to live data from Google Cloud Storage.

Check out the various frameworks supported by Wijmo at https://developer.mescius.com/wijmo.

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