DataBind Controls to Google Data Catalog Data in Delphi

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Google Data Catalog ODBC Driver

The Google Data Catalog ODBC Driver is a powerful tool that allows you to connect with live data from Google Data Catalog, directly from any applications that support ODBC connectivity.

Access Google Data Catalog data like you would a database - read, write, and update Google Data Catalog Schemas, Tables, etc. through a standard ODBC Driver interface.



DataBind to Google Data Catalog data in Delphi with standard data access components and controls.

The CData ODBC Driver for Google Data Catalog supports the ODBC standard to enable integration of live Google Data Catalog data with visual form designers and other rapid development tools in Delphi. The ODBC driver simplifies data access strategies for applications that share a single codebase like Delphi by providing a single API for database development. This article shows how to how to connect to Google Data Catalog data and query data from a simple visual component library (VCL) application, as well as from Delphi code.

Create a FireDAC Connection to Google Data Catalog Data

If you have not already, first specify connection properties in an ODBC DSN (data source name). This is the last step of the driver installation. You can use the Microsoft ODBC Data Source Administrator to create and configure ODBC DSNs.

Google Data Catalog uses the OAuth authentication standard. Authorize access to Google APIs on behalf on individual users or on behalf of users in a domain.

Before connecting, specify the following to identify the organization and project you would like to connect to:

  • OrganizationId: The ID associated with the Google Cloud Platform organization resource you would like to connect to. Find this by navigating to the cloud console.

    Click the project selection drop-down, and select your organization from the list. Then, click More -> Settings. The organization ID is displayed on this page.

  • ProjectId: The ID associated with the Google Cloud Platform project resource you would like to connect to.

    Find this by navigating to the cloud console dashboard and selecting your project from the Select from drop-down. The project ID will be present in the Project info card.

When you connect, the OAuth endpoint opens in your default browser. Log in and grant permissions to the application to completes the OAuth process. For more information, refer to the OAuth section in the Help documentation.

You can then follow the steps below to use the Data Explorer to create a FireDAC connection to Google Data Catalog data.

  1. In a new VCL Forms application, expand the FireDAC node in the Data Explorer.
  2. Right-click the ODBC Data Source node in the Data Explorer.
  3. Click Add New Connection.
  4. Enter a name for the connection.
  5. In the FireDAC Connection Editor that appears, set the DataSource property to the name of the ODBC DSN for Google Data Catalog.

Create VCL Applications with Connectivity to Google Data Catalog Data

Follow the procedure below to start executing queries to Google Data Catalog data from a simple VCL application that displays the results of a query in a grid.

  1. Drop a TFDConnection component onto the form and set the following properties:

    • ConnectionDefName: Select the FireDAC connection to Google Data Catalog data.
    • Connected: Select True from the menu and, in the dialog that appears, enter your credentials.
  2. Drop a TFDQuery component onto the form and set the properties below:

    • Connection: Set this property to the TFDConnection component, if this component is not already specified.
    • SQL: Click the button in the SQL property and enter a query. For example:

      SELECT Type, DatasetName FROM Schemas WHERE ProjectId = 'bigquery-public-data'
    • Active: Set this property to true.
  3. Drop a TDataSource component onto the form and set the following property:

    • DataSet: In the menu for this property, select the name of the TFDQuery component.
  4. Drop a TDBGrid control onto the form and set the following property:

    • DataSource: Select the name of the TDataSource.
  5. Drop a TFDGUIxWaitCursor onto the form — this is required to avoid a run-time error.

Execute Commands to Google Data Catalog with FireDAC Components

You can use the TFDConnection and TFQuery components to execute queries to Google Data Catalog data. This section provides Google Data Catalog data-specific examples of executing queries with the TFQuery component.

Connect to Google Data Catalog Data

To connect to the data source, set the Connected property of the TFDConnection component to true. You can set the same properties from code:

FDConnection1.ConnectionDefName := 'mygoogledatacatalog'; FDConnection1.Connected := true;

Create Parameterized Queries

Parameterized resources can improve performance: Preparing statements is costly in system resources and time. The connection must be active and open while a statement is prepared. By default, FireDAC prepares the query to avoid recompiling the same query over and over. To disable statement preparation, set ResourceOptions.DirectExecute to True; for example, when you need to execute a query only once.

Execute a Query

To execute a query that returns a result set, such as a select query, use the Open method. The Open method executes the query, returns the result set, and opens it. The Open method will return an error if the query does not produce a result set.

FDQuery1.Open('select * from Schemas where ProjectId = :ProjectId',['bigquery-public-data']);