Gallery repeating objects (with rather unique/peculiar data structure)

[MaxDonen]

I appreciate that there are several queries of this type, but unfortunately none of them solve my particular issue as far as I can tell. 

Apologies for the lengthy description-I just want to be clear on what's going wrong. 

I have a collection, Col_CostAnalCompare_Test, which pulls in all data from a static Excel table, CostAnal, when my app starts. The relevant material is attached. 

A separate collection, Col_UserCompare, also pulls in data from a static Excel table, Benchmark_Test, when the user selects a project that they are interested in comparing (see the 'value_if_false' argument in the if statement below). 

If(ThisItem.Description exactin Col_UserCompare.Description, Remove( Col_UserCompare,
Filter( Col_UserCompare, Description=ThisItem.Description ) ) 
,

Collect(
    Col_UserCompare,
    {
        Name:Name,
        Description: Description,
        Project_Sum: Project_Sum,
        Quality_Rating: Quality_Rating,
        New_Build_Or_Refurbishment:New_Build_Or_Refurbishment,
        Airside_Or_Landside:Airside_Or_Landside,
        Lead_Designer:Lead_Designer,
        Principal_Contractor:Principal_Contractor,
        Procurement_Route:Procurement_Route
    }
))

Benchmark_Test and CostAnal are 2 separate tables, but they each feature a column with a Project_ID.  So the Project_ID 'T_DL_1' from Benchmark_Test (and therefore Col_UserCompare) will match a Project_ID from CostAnal (and therefore Col_CostAnalCompare_Test). 

If the user has selected a project to compare, then the following code looks at Col_CostAnalCompare_Test and presents all records  (there are multiple cost entries per project in Col_CostAnalCompare_Test, see the excel for details) where the Project_ID matches the Col_UserCompare_Test Project_ID. 

Filter(Col_CostAnalCompare_Test,Project_ID exactin Col_UserCompare.Project_ID)

Still with me? Hold tight. 

The above code is entered into a gallery, under 'Items'. BUT the actual cost data, derived from Col_CostAnalCompare_Test, is displayed in a subgallery (I tried multiple ways of doing this and this was the only one that permitted scrolling from left to right). 

So you have a gallery with multiple subgalleries. Each subgallery contains cost data. 

But...the subgalleries repeat, seemingly infinitely, within the main gallery. See the attached screenshot. T_DL_1 is shown on the left, followed by T_DL_2 (this is fine, as these are 2 separate projects). But then, as the user scrolls right, T_DL_1 appears again, followed by T_DL_2, followed by T_DL_1...you get the idea. 

Why is this? I tried to implement the 

Last(FirstN(source, number)) solution that I saw elsewhere (yes, I've searched for a fix pretty hard) but I am not sure my own situation is compatible with this. 

Apologies if any of the above is irrelevant to the repeating gallery situation, but I just wanted to give some context in case it's important. 

Any assistance would be much appreciated. 

[v-yutliu-msft]

Do you mean that Col_UserCompare has duplicate data?

Actually, I think what you described is a little complex, so I couldn't quite understand the process.

Could you show me

1)the formula that how do you update Col_UserCompare collection?

2)the items property of the gallery?

You just need to tell me the related information about your issue, no need to describe so detailed.

I suggest you firstly describe how this function works and then show me related formulas.

At last, describe your problem.

Best regards,

[MaxDonen]

Hi, sorry for the lack of clarity.

Col_UserCompare does not contain duplicate data. The horizontal gallery displays infinite subgalleries (each of which display data derived ultimately from Col_UserCompare, but I don't think the data is the cause of the issue.

<quote>

1)the formula that how do you update Col_UserCompare collection?

</quote>

When the 'Add this project to comparison list' button is selected, the following 'Onselect' code is run.

Collect(Col_UserCompare,Filter(Col_SelectedProjects,ThisItem.Description exactin Description)))​

<quote>

2)the items property of the gallery?

</quote>

The 'Items' property of the main gallery is as follows:

Filter(Col_CostAnalCompare_Test,Project_ID exactin Col_UserCompare.Project_ID)

The 'Items' property of the subgallery, nested inside the main gallery, is as follows:

Filter(Col_CostAnalCompare_Test,Shown=true,Project_ID=ThisItem.Project_ID)​

My issue is that the gallery repeats the subgalleries over and over again.

So if Project_1 is contained in the  Col_UserCompare, the main gallery's records show lots of subgalleries, with each subgallery showing the cost records for Project_1.

If Project_1 and Project_2 are contained in Col_UserCompare, then the main gallery displays the subgallery (containing the cost records) for Project_1, then the subgallery for Project_2, then it repeats (Project_1, Project_2,Project_1,Project_2 etc).

I am trying to find a way to eliminate the duplication, so that if Project_1 is contained within Col_UserCompare, then the main gallery should only show 1 subgallery: the cost records for project 1.

Likewise, if Project_1 and Project_2 and contained within Col_UserCompare, then the main gallery should show 2 subgalleries: Project_1 and Project_2.

I note that changing the 'items' property of the main gallery to just Col_CostAnalCompare_Test does not solve the issue described below, since the main gallery repeats the subgalleries just the same. Of course, without the filter, it displays all projects in the Col_CostAnalCompare collection. There are currently 3 projects in this collection, so it repeats Project_1, Project_2,Project_3,Project_1,Project_2, etc. 

I trust this is more helpful than the initial description I gave, but do please let me know if any further info is required.

Thanks.