PL-900 Demonstrate the capabilities of Power Apps Practice Question
A company uses a Power App to track inventory. The app displays a gallery of items filtered by a dropdown. When the user selects 'Electronics', the gallery shows all electronics items. However, after the user clears the dropdown, the gallery remains empty. What is the most likely reason?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
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The gallery's Items property uses a filter that references Dropdown.Selected.Value, and when the dropdown is cleared, the filter returns blank
When the dropdown is cleared, Dropdown.Selected.Value becomes blank. The gallery's Items property uses a filter that references this value, so the filter returns blank (no items), causing the gallery to be empty. Option A is incorrect because AllowEmptySelection set to false would prevent clearing, not cause emptiness after clearing. Option B is incorrect because the data source does not require a refresh; the issue is the filter logic. Option D is incorrect because OnStart is not involved in the clearing behavior.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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The dropdown's AllowEmptySelection property is set to false
Why it's wrong here
AllowEmptySelection governs whether the dropdown can hold no value; setting it false prevents clearing, yet the stem shows clearing succeeded, so it cannot explain an empty gallery. It is tempting because it concerns empty selections, and it would be correct if the dropdown refused to clear at all.
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The data source requires a refresh after clearing selection
Why it's wrong here
Power Apps galleries re-evaluate their Items formula automatically when a control changes, so no manual refresh is required; the empty result stems from the filter logic itself. It is tempting because stale data is a familiar symptom, and a refresh would be correct after external data-source changes outside the app.
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The gallery's Items property uses a filter that references Dropdown.Selected.Value, and when the dropdown is cleared, the filter returns blank
Why this is correct
Clearing the dropdown sets Dropdown.Selected to blank, so Dropdown.Selected.Value returns nothing. The Filter expression then matches no records, leaving the gallery empty. The Items property must handle the blank case, typically via an If or Coalesce wrapper.
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The app's OnStart property is clearing the data source
Why it's wrong here
OnStart runs once when the app launches, not when the dropdown changes, so it cannot empty the gallery after a clear. It is tempting because OnStart can reset collections and variables, and it would be correct if the gallery's data were being wiped on every app load.
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