The Define Data dialog box enables you to choose the data service fields for an element, and specify their default values. For UI elements, the Define Data dialog box also enables you to choose the control to display for each field, or whether to hide the control (and thereby remove the field from the UI element). If the data service has field label values defined for the fields, you can choose whether to display them in the Define Data dialog box.
If you add an element to the model by dragging out from a data service that includes a large number of fields, the Define Data dialog box opens automatically. You can also display the Define Data dialog box at any time by right-clicking the element icon on the Design board and choosing Define Data from the context menu. For more information about the options in the Define Data dialog box, see Define Data Dialog Box in the Visual Composer Reference Guide.
You can use the Initialize Data dialog box (opened from the Define Data dialog box) to initialize values for connectors (Start Point, End Point, Signal In, Data In and Data Store). For more information about the options in the Initialize Data dialog box, see Initialize Data Dialog Box in the Visual Composer Reference Guide.
You can define virtual fields for an element. Virtual fields are fields that are not returned by a data service, and are defined manually in the Define Data dialog box. Field names are case-insensitive, and can contain only ASCII characters, digits, and underscores. They cannot contain spaces, cannot start with a digit, and must be unique within the same data structure level.
Virtual fields enable you to correct mismatches between data services. For example, suppose certain information is expected in the element to which data is being transferred, but the data (and corresponding field) does not exist in the original data service. In this case, you can create a virtual field so that the runtime user can enter the required data before transferring the field to the target element.
You can also use virtual fields to transfer data without it being visible to the runtime user. For example, you may want to use a virtual field of type Time to add a time stamp to data so that you can filter displayed information according to the time stamp. Using a virtual field in this case enables you to transfer the time stamp information without showing it to the runtime user. To enable the runtime user to view the time stamp information, you can bind the virtual field to a control to make it visible.
If an element contains a clustered dataset (a dataset containing nested tables and structures), you need to first choose the source data node for the element, and then define the fields. The fields are defined as if the dataset was flat. Since the following children of the view element are dependent on the source node data, you cannot change them after you choose the source node.
When working with clustered datasets, you can use the Initialize Data dialog box to initialize values for the dataset using input connectors (Start Point, End Point, Signal In, Data In and Data Store). You access the Initialize Data dialog box from the Define Data dialog box. For more information about the options in the Initialize Data dialog box, see Initialize Data Dialog Box in the Visual Composer Reference Guide.