@Brian-M - typically, we create a Single Line Text Column in SharePoint, and then insert that Single Line Text field as a DataCard into an EditForm control.
We then remove the Text Input control inside that DataCard, and replace it with a different control (in your scenario, a Combo Box control). We also set the Update property of the DataCard to point at the selected value from that Combo Box.
However, if we add the following into the DefaultSelectedItems property, we see the following error:
The ComboBox is expecting a Table. As a workaround, and as you have correctly done, we can force a Value into the DefaultSelectedItems property using:
{
Value: Parent.Default
}
However, this approach does not work with Choice data types or Single Line Text data types in Dataverse. If for any reason we want to reference an existing saved selection from a ComboBox control, we run into trouble. If you add a Label control and reference the ComboBox, even though a Value is “displayed”, the ComboBox will still return blank. This is because the DefaultSelectedItems property for that control is expecting a record.
In many scenarios, this may not be an issue because we only need to be confident that the correct value is being displayed for the selected record in our Edit Form. We know if the user "re-selects" the Combo Box and selects a different value, the Combo Box will accept the new selected record and this selection will successfully save on SharePoint.
To supply a record into the ComboBox, we can force the correct record into the ComboBox using the Lookup function. In the DefaultSelectedItems property of the ComboBox, try:
LookUp(
'Your List',
'Your Single Line Text Volumn' = Parent.Default
)
