ComboBox default not updating default text box

[tkshepley]

I have a ComboBox set with a default selected value and a text box that references the field, however the text box field does not update with the default text box.  Any help would be greatly appreciated.  

ComboBox

DefaultSelectedItems - ["User Name"]

Text Box

Default Text box-  Combobox.selected.Email

[Amik]

@tkshepley - are you using an Edit Form?

[tkshepley]

Yes, in edit form.  When I select a different option in the drop down it works, but it just will not work with the defaultselecteditem, it leaves the text box blank.  Thank you!

[Amik]

@tkshepley -  assuming you're using SharePoint, 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, 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 or a Text Input control as you have done, and reference the ComboBox, even though a Value is “displayed” in the ComboBox, the Label/Text Input control 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.

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 Column' = Parent.Default
)

[tkshepley]

That does not select the DefaultSelectedItems either, I was able to get it to work with {Value: "Name"} and it shows in the field, however it does not actually select it and write it back to the Dataverse column.

[Amik · Accepted solution]

@tkshepley - the same principles above also apply to Dataverse.

As explained, both the ComboBox control, and the Column you're trying to update, requires you to pass a record. 

Assuming you're trying to update a People column - a complex field type such as a people column requires a record and a record can contain several attributes (Primary Email, User Name etc)

I would expect the Default property of the DataCard to contain:

ThisItem.'Your People Field'

And the DefaultSelectedItems property to contain:

Parent.Default

However, you have decided to pass a Value into this property instead of a record. Why?