Build Apps with Live Google Cloud Storage Data Using the Low-Code Development Platform of Mendix

Mendix, developed by Siemens, is a low-code platform used to rapidly develop, test, and deploy web and mobile applications, facilitating digital transformation and enhancing business agility. When paired with the CData JDBC Driver for Google Cloud Storage, you can use your Google Cloud Storage data to create various applications using Mendix Studio Pro.

With built-in optimized data processing, the CData JDBC driver offers unmatched performance for interacting with live Google Cloud Storage data. When you issue complex SQL queries to Google Cloud Storage, the driver pushes supported SQL operations, like filters and aggregations, directly to Google Cloud Storage and utilizes the embedded SQL engine to process unsupported operations client-side (often SQL functions and JOIN operations). Its built-in dynamic metadata querying allows you to work with and analyze Google Cloud Storage data using native data types.

This article shows how you can easily create an application that utilizes Google Cloud Storage data in Mendix by combining the JDBC interface provided by Mendix with the CData JDBC Driver for Google Cloud Storage.

Preparing the Mendix environment

In this section, we will explore how to develop an app using Mendix Studio Pro, as previously introduced, with Google Cloud Storage data. Be sure to install Mendix Studio Pro beforehand.

Install the CData JDBC Driver for Google Cloud Storage

First, install the CData JDBC Driver for Google Cloud Storage on the same machine as Mendix. The JDBC Driver will be installed in the following path:

Create an application

Now let's start creating the app. First, let's make an app that has the Database Connector available.

1. Launch Mendix Studio Pro and click 'Create New App.'
2. Select the 'Blank Web App' option.
3. Click 'Use this starting point' to proceed.
4. Create an app with a name of your choice. Also, note down the "Disk location" information, for future reference.
5. You have now created a brand-new app.

Add the Database Connector to your application

Next, add the Database Connector module to the app you just created.

1. On the top right, click on the Marketplace button.
2. Search for Database Connector in the Marketplace search section and select it.
3. Click on Download to download the latest Database Connector.
4. In the Import Module window, select the Action as Add as a new module.
5. If the Database Connector appears on the app screen, you are good to move on to the next steps.

Adding the JDBC Driver to Mendix Studio Pro

To use the CData JDBC driver with this Database Connector, you must add the JDBC Driver JAR file to your project.

1. In the Mendix project folder you noted earlier, there is a folder named 'userlib.' Place the two files, 'cdata.jdbc.googlecloudstorage.jar' and 'cdata.jdbc.googlecloudstorage.lic,' into that folder.
2. You can now use the CData JDBC Driver with the Database Connector.

Create a Data Model

Now, let's create an app. We first need to define a data model to load data from the Database Connector and display it on the list screen. Let's create the data model before loading the data.

1. Add an Entity to the 'Domain model' of MyFirstModule.
2. Enter the entity name and field definitions.
3. You can easily configure the data by checking the table definition information through the CData JDBC driver using a tool such as DBeaver.
4. Define the entities.

Create a constant for the JDBC URL

Next, create a JDBC URL constant to use with the Database Connector.

1. Add 'Constant' to MyFirstModule.
2. Add a name to the Constant in the Add Constant window.

3. Generate a JDBC URL for connecting to Google Cloud Storage, beginning with jdbc:googlecloudstorage: followed by a series of semicolon-separated connection string properties.

   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.

   Built-in Connection String Designer

   For assistance in constructing the JDBC URL, use the connection string designer built into the Google Cloud Storage JDBC Driver. Either double-click the JAR file or execute the jar file from the command-line.

   java -jar cdata.jdbc.googlecloudstorage.jar

   Fill in the connection properties and copy the connection string to the clipboard.

   A typical JDBC URL is below:

   jdbc:googlecloudstorage:ProjectId='project1';InitiateOAuth=GETANDREFRESH
4. Specify the connection string copied from the previous step in the Default value section and click on OK.

Create a microflow to retrieve Google Cloud Storage data

Let's create a microflow that retrieves data from the Database Connector based on the entity we created.

1. Click 'Add microflow' from MyFirstModule.
2. Create a microflow with any name.
3. First, create an object for the entity you defined earlier. Then, add the 'Create Object' action to the microflow.
4. Click on the 'Select' button for Entity in the Create Object window.
5. Select a previously defined Entity.
6. Enter an arbitrary Object name and click OK.
7. Next, add an Execute Query action to the microflow to retrieve data from the Database Connector.
8. Define each input in the Execute Query window.
9. In "jdbc url", specify the constant you defined beforehand.
10. In SQL, write a query to retrieve data from Google Cloud Storage.
11. You don't need a Username or Password this time, so set them to 'empty' and assign the object created in the previous flow as the Result object. Then, simply specify any name you prefer for the List in the List Name section.
12. Finally, define the output of the microflow.
13. Double-click the End Event to open it, select 'List' from the Type dropdown, and link it to the Entity you defined earlier. Then, set the output result of Execute Query as the Return value.
14. This completes the microflow that retrieves data from Google Cloud Storage.

Create a list screen and link it to a microflow

Finally, let's create a screen that displays the results obtained from the microflow.

1. Double-click 'Home_web' inside the Toolbox menu to open it.
2. Drag and drop a Data grid template from the Data containers section into the list screen.
3. Once you have placed the Data grid, double-click on it to display the Edit Data Grid settings screen.
4. Navigate to the Data source tab and link the data source type with the Microflow.
5. Select the microflow you just created.
6. Now click OK.
7. When you click OK, you'll be prompted to auto-detect columns. Simply click 'Yes' to proceed.
8. Next, you'll be prompted to generate controllers for various Data grids. Since we won't be configuring the logic for each one this time, click 'No.'
9. This will create a simple data grid screen as shown below.

Try it out

Now let's check if it works properly.

1. Click the 'Publish' button to prepare the app you created. Once that's done, click 'View App' to open the app.
2. If you see a list of Google Cloud Storage data like the one below, you're all set! You've successfully created a Google Cloud Storage-linked app with low code, without needing to worry about Google Cloud Storage's API.

Get Started Today

Download a free 30-day trial of the CData JDBC Driver for Google Cloud Storage with Mendix, and effortlessly create an app that connects to Google Cloud Storage data.

Reach out to our Support Team if you have any questions.