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Toggle OnChange event, when fired from a button, executes twice instead of once

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Posted on by vllanso

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Hello,

I have created a demo app where a button fires a toggle control, and to my surprise (or to my misunderstanding) the toggle OnChange event is running twice instead of once.

So I have:

- a variable named tmpcounter that OnStart of the App is set to 0

- a toggle control which its default value is based on a boolean variable (tmptoggleflag). This variable is initially set to false on the OnStart App event

- a button that, OnSelect, sets the boolean variable tmptoggleflag to true, to trigger the toogle

- the toggle OnChange event sets the boolean variable tmptoggleflag to false and increases the counter tmpcounter +1

When I run the sample application, every time I click the button, the counter tmpcounter is increased by 2, not by 1, so it looks like the OnChange event of the toggle is firing twice instead of once.

How/why is that possible ? What am I missing ?

Shouldn't the counter increase only by 1 ? Or what should I do so the toggle OnChange event is only fired once ?

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Building Power Apps

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GarethPrisk 2,828 on at

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Boolean controls have an OnChange, OnCheck (True), and OnUncheck (False).
At times, you can accidentally get into a recursive loop where the Toggle is being changed by a function which changes it again.
Instead, consider using OnSelect to set the value, or hook the explicit true or false triggers.
vllanso 143 on at

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Thank you Gareth, that was fast !

I have moved the code from the OnChange to the OnCheck event of the toggle, and certainly now it is working as I expected and the counter is increased only once.

Thanks again !!
TB-13091842-0 140 on at

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I've been working on a matter like this and was running into some toggle problems. Your solution worked because OnCheck only triggers when the value changes to true. The OnChange action is triggered whenever the variable changes, whether from false to true or from true to false. So you triggered the action once when you changed it to true in the button, and triggered it a second time when you changed it from true to false in the OnChange action.

You can get around this another way: the button sets the Variable = !Variable, and then the original action in OnChange, minus the Variable change, will fire only once.

These both accomplish the same goal, but changing the Variable only once is cleaner.