DataBind Controls to Neo4J Data in C++Builder

The CData ODBC Driver for Neo4J makes it easy to integrate connectivity to live Neo4J 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 Neo4J 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 Neo4J 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.

To connect to Neo4j, set the following connection properties:

• Server: The server hosting the Neo4j instance.
• Port: The port on which the Neo4j service is running. The provider connects to port 7474 by default.
• User: The username of the user using the Neo4j instance.
• Password: The password of the user using the Neo4j instance.

You can then follow the steps below to use the Data Explorer to create a FireDAC connection to Neo4J.

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 Neo4J.

Create VCL Applications with Connectivity to Neo4J Data

Follow the procedure below to start querying Neo4J 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 Neo4J.
   • 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 CategoryId, CategoryName FROM ProductCategory WHERE CategoryOwner = 'CData Software'
   • 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 Neo4J with FireDAC Components

You can use the TFDConnection and TFQuery components to execute queries to Neo4J data. This section provides Neo4J-specific examples of executing queries with the TFQuery component.

Connect to Neo4J 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 Neo4J 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.