Author: Jim T1392
TBindList can iterate through the records in a TClientDataSet and fill a TListBox. Here is how to configure TBindList in the designer.
Drop a TClientDataSet and a TDataSource on a form. Load some data into the dataset such as biolife.xml (Right click ClientDataSet1, choose “Load from MyBase table…”, browse to the sample data directory and choose biolife.xml). In the object inspector, set DataSource1.DataSet to ClientDataSet1. Drop a TBindScopeDB component on the form and set BindScopeDB1.DataSource to DataSource1.
BindScopeDB1 connected to DataSource1
New LiveBinding... command for ListBox1
Click “New LiveBinding…” and choose TBindList.
New LiveBinding dialog box
Double click or press OK. The New LiveBindings dialog creates a TBindingsList component and a TBindList component. TBindingsList is a container for binding components just as TActionList is a container for actions. Double click on TBindingsList to see the new TBindList component.
TBindingsList contains a TBindList component
Click on BindListListBox11 to show the properties of the new TBindList component. The ControlComponent property was set to ListBox1 by the “New LiveBinding…” command.
BindList1 with ControlComponent set to ListBox1
Use the object inspector to set the SourceComponent to BindScopeDB1. Set SourceMemberName to the name of a field. The SourceMemberName property editor should provide a drop down list of field names. If not, then the data components are probably not connected (DataSource1.DataSet must be set to ClientDataSet1 and BindScopeDB1.DataSource must be set to DataSource1).
BindList1 SourceComponent and SourceMemberName
The final step is to enter the binding expressions. Open the expressions editor by clicking the “Expressions…” command at the bottom of the object inspector.
BindList1 Expressions Editor
Select the “Format” collection and click the “Add Expression” button to add a new binding expression. Enter “Text” as the control expression. Enter “AsString” as the source expression.
BindList1 Format binding expression
Be sure that you’ve added to the “Format” collection and not the “FormatControl” collection.
The buttons at the bottom of the window are used to test the expressions. Click “Eval Source” to evaluate the expression “AsString” against the Category field.
Expression Result Window
Close the Expression Result window. Also close the expression editor.
At the bottom of the object inspector are two commands for trying out TBindList at design time. Click “Fill List” to populate ListBox1.
BindList1 fills ListBox1
Now click “Clear List”.
Run the project. ListBox1 is populated with the values of the Category field.
- ListBox1 populated by BindList1 at runtime
VCL and FireMonkey sample projects using TBindList are available on sourceforge:
Design. Code. Compile. Deploy.
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