DataBind Controls to Greenhouse Data in C++Builder

The CData ODBC driver for Greenhouse makes it easy to integrate connectivity to live Greenhouse data with standard data access components in C++Builder. This article shows how to create a simple visual component library (VCL) application in C++Builder that connects to Greenhouse data, executes queries, and displays the results in a grid. An additional section shows how to use FireDAC components to execute commands from code.

Create a Connection to Greenhouse 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.

You need an API key to connect to Greenhouse. To create an API key, follow the steps below:

1. Click the Configure icon in the navigation bar and locate Dev Center on the left.
2. Select API Credential Management.
3. Click Create New API Key.
• Set "API Type" to Harvest.
• Set "Partner" to custom.
• Optionally, provide a description.
4. Proceed to Manage permissions and select the appropriate permissions based on the resources you want to access through the driver.
5. Copy the created key and set APIKey to that value.

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

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 Greenhouse.

Create VCL Applications with Connectivity to Greenhouse Data

Follow the procedure below to start querying Greenhouse 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 Greenhouse.
   • 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 Id, CandidateId FROM Applications WHERE Status = 'Active'
   • 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 Greenhouse with FireDAC Components

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

Connect to Greenhouse 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:

To connect the TFDQuery component to Greenhouse data, set the Connection property of the component. When a TFDQuery component is added at design time, its Connection property is automatically set to point to a TFDConnection on the form, as in the application above.

Create Parameterized Queries

To create a parameterized query, use the following syntax below:

The example above binds a string-type input parameter by name and then opens the dataset that results.

Prepare the Statement

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.

Related Articles

Below you can find other articles for using the CData ODBC Driver with RAD Studio, Delphi, and C++ Builder.

• DataBind Controls to Greenhouse Data in Delphi
• Viewing Greenhouse Data in RAD Studio Data Explorer
• Build a Simple VCL Application for Greenhouse Data