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Working with Field Component Methods at Runtime
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Field components methods available at runtime 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 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's data-aware components with a field's 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's FocusControl method before validating the field. The following code illustrates how to call the FocusControl method for the Company field in the Customers table:

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    CustomersCompany.FocusControl;

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    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 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's 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.

See Also

Persistent Field Components

Displaying

Setting a Default Value for a Field

Working with Constraints

Using Object Fields

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