Overview

A subform is a form included in another form.

There are two main types of subforms:

• List subforms, generally intended to enter, display and modify data coming from other tables,
• Page subforms, which let you use specific sophisticated interface objects, such as 4D widgets for example.

Each type of subform has its own particular mechanisms and properties.

In order to clearly define the concepts implemented with subforms, here are some definitions for certain terms used:

• Subform: a form intended for inclusion in another form, itself called the parent form.
• Parent form: a form containing one or more subform(s).
• Subform container: an object included in the parent form, displaying an instance of the subform.
• Subform instance: the representation of a subform in a parent form. This concept is important because it is possible to display several instances of the same subform in a parent form.
• List form: instance of subform displayed as a list.
• Detail form: page-type input form associated with a list-type subform that can be accessed by double-clicking in the list.

You can add a subform to a form in three ways:

• In the Form Wizard, using the Subform page in the Advanced options (see Creating a form using the Form Wizard)
• In the Form editor, using the Subform tool of the object bar ,
• In the Form editor, by dragging and dropping from the Forms Page of the Explorer.

Note: A subform type object (in page form) is also created when you add a Widget object from the preconfigured object library (see Using the preconfigured library).

Of course, you can mix these different techniques according to your needs.

You specify the form type by checking (or unchecking) the Output subform option in the "Sub-Form" theme of the Property List. Checking or unchecking this option updates the other options displayed in the Property List so that they correspond to the chosen subform type. 

4D widgets are predefined compound objects. These widgets, which can be used with or without programming, give access to standard functionalities that are very simple to implement. The following widgets are available:

• MissingRef: search area with standard appearance.
• DatePicker: date selector.
• TimePicker: time selector.

4D widgets are page-type subforms endowed with specific functions. You can add them to your forms using the subform creation tool (see previous section) or using the integrated object library of 4D (see Using the preconfigured library).

The use of widgets is described in detail in a separate manual, 4D Widgets