Problem with expression binding on a dataset

Ignition
1

Hello all,

I have a custom property on the root container with a named query binding.
A set of drop downs with the data bound to a dataset (from a named query), and the selectedValue of the drop down is bound using an expression:

try({Root Container.current_oamb_pos}[{Root Container.Container OAMB Locations.Dropdown Location 1.row},'Position_ID'], 0)

The current_oamb_pos is the dataset supporting the drop down selectedValue.

In the Designer, each drop down has the correct selected value, but it does not display a label or string.
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Once I go into Preview Mode, then the correct strings appear.
When I open the project, and enable the trial, the correct strings in the drop down do not appear, just as in the Designer without preview mode.

I threw a table bound directly to the .current_oamb_pos just to make sure the data was really there when the screen loaded.

I seem to remember reading a thread on data loading via queries versus component loading and firing binding events, but I cannot seem to find it (if it really applies anyway).

What am I missing?

2

Just want to put this near the top again. :slight_smile:

3

I have no idea what might be wrong. Probably something simple you haven't shared. Perhaps you should be using the dropdown's .selectedIndex to pick adjacent data from the dropdown's option data.

4

I don't see a selectedIndex available.

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5

I discovered that if I replace the reference to the drop down custom property .row in the expression with a hard value, it works just fine.

I knew something was tickling the back of my brain on the timing of loading components, data and bindings, and I think this type of expression binding is what I was thinking of. Even though it's bound, I think if I could delay the firing of the expression or delay these particular components to load late, that may work. But I don't know if such a thing is possible.

For now, simply hard coding the row number will work just fine.

Edit:
Also, I think I need to set the behavior.noSelectionValue to zero...

6

.selectedIndex is not shown in the property editor, but is shown in the property binding selection dialog. You should use it for all indirection into the data prop.