Working with Field Component Methods at Runtime
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Field components methods available at run time enable you to convert field values from one data type to another, and enable you to set focus to the first data-aware control in a form that is associated with a field component.
Controlling the focus of data-aware components associated with a field is important when your application performs record-oriented data validation in a dataset event handler (such as Data.DB.TDataSet.BeforePost). Validation may be performed on the fields in a record whether or not its associated data-aware control has focus. Should validation fail for a particular field in the record, you want the data-aware control containing the faulty data to have focus so that the user can enter corrections.
You control focus for a field data-aware components with a field FocusControl method. FocusControl sets focus to the first data-aware control in a form that is associated with a field. An event handler should call a field FocusControl method before validating the field. The following code illustrates how to call the FocusControl method for the Company field in the Customers table:
CustomersCompany.FocusControl;
CustomersCompany->FocusControl();
The following table lists some other field component methods and their uses. For a complete list and detailed information about using each method, see Data.DB.TField.
Selected field component methods:
| Method | Purpose |
|---|---|
|
AssignValue |
Sets a field value to a specified value using an automatic conversion function based on the field type. |
|
Clear |
Clears the field and sets its value to NULL. |
|
GetData |
Retrieves unformatted data from the field. |
|
IsValidChar |
Determines if a character entered by a user in a data-aware control to set a value is allowed for this field. |
|
SetData |
Assigns unformatted data to this field. |