Problems with if

[chrisegger]

Whats wrong with this Code:

If(
    varIntID=Or("2021a";"2021b";"2021c");
    Refresh('tbl-SuS_Daten-2021a_b_c');;
    Clear(SuSCollection);;
    Collect(SuSCollection;Filter('tbl-SUS';StartsWith(Title;varIntID));;
    If(IsBlankOrError('tbl-SuS_Daten-2021a_b_c');Button3_1.Visible=true;false);

    varIntID=Or("2020a";"2020b";"2020c");
    Refresh('tbl-SuS_Daten-2020a_b_c');;
    Clear(SuSCollection);;
    Collect(SuSCollection;Filter('tbl-SUS';StartsWith(Title;varIntID));;
    If(IsBlankOrError('tbl-SuS_Daten-2020a_b_c');Button3_1.Visible=true;false)
);

But this works:

Refresh('tbl-SuS_Daten-2021a_b_c');;
Clear(SuSCollection);;
Collect(SuSCollection;Filter('tbl-SUS';StartsWith(Title;varIntID));;
If(IsBlankOrError('tbl-SuS_Daten-2021a_b_c');Button3_1.Visible=true;false)

There must be a mistake with the if function!

Thanks for helping

[RandyHayes · Accepted solution]

@chrisegger 

In PowerApps you cannot set a property with an equal operator. Button3_1.Visible=true is a comparison operation, not an assignment.

Since PowerApps is not a development platform, it gets values by reference and formulas, just like Excel (as it was modeled around Excel).

So, your formula on the button Visible property should be:  IsBlankOrError('tbl-SuS_Daten-2021a_b_c')

Your other formula you posted should be:

If(
    varIntID in "2021a|2021b|2021c";
        Refresh('tbl-SuS_Daten-2021a_b_c');;
        ClearCollect(SuSCollection; Filter('tbl-SUS'; StartsWith(Title;varIntID));
    
    varIntID in "2020a|2020b|2020c";
        Refresh('tbl-SuS_Daten-2020a_b_c');;
        ClearCollect(SuSCollection; Filter('tbl-SUS';StartsWith(Title;varIntID))    
);

I would assume you are refreshing the datasource because this is a multiperson app where others are changing records constantly.  If not, then I would eliminate the Refresh operations as they are performance expensive and not needed.

I hope this is helpful for you.

[TheRobRush]

Thats a good point for him @RandyHayes  from what I have seen of other aspects of his app, each person will only ever alter their own classes students, so there should be no changing data conflicts and the refresh will not be needed

[RandyHayes]

@TheRobRush 

Yes, Refresh is only needed when there will be external (outside of the app...including another copy of the app running) that will alter the datasource and the app needs to have refreshed data of those changes.

Beyond that, it is not needed.

And...actually, if you are not referencing the record elsewhere in the app, PowerApps will actually refresh its own record from the datasource if there are changes as soon as you first access it (this is another topic!)

[chrisegger]

thanks a lot you guys

[chrisegger]

@TheRobRush 
Everything would be easier, if I had only one sharepointlist.
If I would calculate:
I've got 12 classes with each 25 pupils and each year maybe 20 queries resulted to

a minimum of 6000 records (a record has 10 columns) (if I clean the list every year)

Is this not too much??

[TheRobRush]

Yes and no. Yes in that Powerapps caps out at 2000 items pulling from sharepoint in a single query.

But NO because the way your data needs to be laid out is a simple = filter, = this teachers name 

Check out Sharepoint Delegation in Powerapps to learn moreand Also @WarrenBelz amazing resource of Practical PowerApps so ya, I do not see this being an issue for a simple filter like your data would require.

And then make yourself a Flow, to automate the list cleanup at the end of the year

[TheRobRush]

or = class number, however you decide to identify them apart from one another

[chrisegger]

So I can Do IT with only one splists. 

and How can I clean the list every year automatically? 

[TheRobRush]

Yes, you can do it with a single list. And the cleaning of the list will be via a flow, done at end of year (Microsoft Power Automate) Will basically set up a scheduled flow, have it run on a specific date, and run a do until it has gotten and removed all the items on your list, and then once it has completed it will go back to sleep until the specified time (In your case 365 days later)