Groupby Error: "The first argument to the GroupBy function cannot be blank"

[kky1]

Hello - I'm running into an error with a nested gallery using groupby and would be grateful for help in how to fix it.

My original data source has multiple records as such:

The data source of the main gallery is a grouped collection on app OnStart. 

ClearCollect(colGroupedMaterials, GroupBy(v_NomMaterials, "Award_ID", "AwardName","DATA"));

 The Items of the nested gallery groups the data again by "Requirednominationmaterials" and "MaterialSortOrder": 

SortByColumns(
    GroupBy(
        ThisItem.DATA,
        "MaterialSortOrder",
        "Requirednominationmaterials",
        "DATA2"
    ),
    "MaterialSortOrder",
    SortOrder.Ascending
)

If I navigate to my AwardsDetails screen from the galleries on these screens, it displays data as desired:

This navigation happens from the screens circled above from HTML text OnSelect property:

Select(Parent); Set(selectedAward, ThisItem); Set(fix,false); Navigate (AwardsDetails)

But when I navigate to AwardsDetails screen from a different screen/gallery, I get this error even though it mimics the other screens and resets the selectedAward variable:

On the MyNomination screen, I first set selectedAward2 on button or HTML text OnSelect:

Select(Parent); Set(selectedAward2, ThisItem); Set(fix,true);
Set(
        varFormData2,
        ThisItem);
Set(varFormMode, FormMode.View);
Navigate(AwardsDetails)

Then I reset the variable to selectedAward in the OnVisible property of the AwardsDetails screen. Testing this, I can see it works and resets the item correctly. But, I still get this error. 

If(fix=true, Set(selectedAward, selectedAward2))

I'm at a loss as to how to fix this. I tried the solution from a similar post solved by @WarrenBelz (https://powerusers.microsoft.com/t5/Building-Power-Apps/GroupBy-error/m-p/2055654#M513912) but that solution only threw more errors.

Any advice would be greatly appreciated. 

@kky1 

[WiZey]

Hello @kky1 ,

First, you don't need to write "fix=true" in your "If()" statement. "fix" is already a boolean and writing the condition this way can actually confuse Power Apps. I recommend simply writing like this:

If(fix, ...)

Second, do you need to populate "selectedAward2" instead of directly populating "selectedAward"? I'm suspecting either "selectedAward2" is blank when you try using "Set()", or doesn't have the record you're expecting when navigating to the screen.

Is "selectedAward" and "selectedAward2" using the same datasource?

[kky1]

Thank you@WIZey! I wasn't aware that fix was a function on its own!

Last night, I began thinking my issue is exactly what you suspect and has to do with my data sources. PowerApps threw an error on the MyNominations page that selectedAward variable conflicted with uses in other places in the app, which is why I tried setting selectedAward2 and then overwriting selectedAward.

My data source for the gallery in the groupby is the same; however, the screens in which I use to navigate to the page have different data sources: One displaying awards and their info in sql, the other displaying nominations a person has made being written to Sharepoint (to utilize an attachment control).

I moved the nomination data to sql and created a new view to combine the award information with the nomination information. Will this solve the issue or is there a better method/tutorial to help me "connect" this all together by Award_ID?  

So, here is the structure of my datasource for the award info:

And here is the new data source for the MyNominations gallery. I basically just combined the view above with the nomination data:

How do other people handle this type of scenario? My app is a multi-screen form (@12 screens) to capture the different data points depending upon the award selected, so I was hoping to tap into this form in edit mode when a user saves their nomination to upload materials and submit at a later time. 

Again thank you for your guidance!

[WiZey · Accepted solution]

It's possible to use a view with the SQL Server connector, but I can't help here as I'm working more often with SharePoint lists.

Let's see if I understood your situation:

You have an "Awards List" screen with a gallery listing all your awards. On selection, it populates "selectedAward" with the selected item which is a record from the "Award" table then navigates to "Award Details" screen.

Then you have a "Nominations List" screen with a gallery listing all your nominations. On selection, you populates "selectedAward" with the selected item which is a record from the "Nomination" table which also contains data about the award.

If this is right, then I'm guessing you have an "Award ID" in your "Nomination" table, which you can use to look up for the record in the "Award" table.

OnSelect: Set(selectedAward, 
  LookUp(Award, Award_ID = ThisItem.Award_ID)
)

This should be the simplest method to get the award's record from the table while giving the variable "selectedAward" the exact same structure in both screens.

Would that fit in your app?

[kky1]

Thank you @WiZey for assisting me through this issue. I've added your suggestion into an if statement (my award info screens are 3 sql views with the same columns) and the app now allows me to set selectedAward from the award info screens and the my nomination screen; however, I am still getting the GroupBy error when I navigate to a details screen from the gallery in MyNominations. 

I noticed when I go into my variables page that when I navigate from the award screens, it populates the selectedAward record variable, but when I try the same thing from the MyNominations screen, the record value is empty. I wonder if my If Statement is wrong...

It is on the OnSelect property of the HTML text and buttons in my gallery to navigate to the other screens. It isn't throwing an error but also doesn't create the variable record.

Select(Parent);
If(
    !IsEmpty(
        LookUp(
            v_FacultyAwardsGallery,
            Award_ID = ThisItem.Award_ID
        )
    ),
    Set(
        selectedAward,
        LookUp(
            v_FacultyAwardsGallery,
            Award_ID = ThisItem.Award_ID
        )
    ),
    !IsEmpty(
        LookUp(
            v_StaffAwardsGallery,
            Award_ID = ThisItem.Award_ID
        )
    ),
    Set(
        selectedAward,
        LookUp(
            v_StaffAwardsGallery,
            Award_ID = ThisItem.Award_ID
        )
    ),
    Set(
        selectedAward,
        LookUp(
            v_StudentAwardsGallery,
            Award_ID = ThisItem.Award_ID
        )
    )
);
Navigate(AwardsDetails)

I checked my data source in sql Award_ID is an integer and in SP list it is a number. Is there something wrong with the code above? Thank you again for your guidance - very much appreciated. 

[WiZey · Accepted solution]

"IsEmpty()" is not appropriate to check if a record exists. It serves to check if a table contains at least one record or not.

Try with "IsBlank()" and see if it works better.

[kky1]

THANK YOU!!!! It worked! OMG, thank you so much! I have to do a demo tomorrow of this app and I had almost given up on getting this to work! Honestly - you Super Users are worth your weight in gold!