Strange behaviour with Patch, AddColumns and nested tables

(0) Share

Report

Posted on by MichaB12

Hi,

I have 2 collections, c1 just contains values, and c2 is the result of a groupBy of b column of c1:

ClearCollect(c1, {a:1, b:1}, {a:2, b:1}, {a:3, b:3}, {a:4, b:1});
ClearCollect(c2, GroupBy(c1,"b", "rest"))

So in the c2 collection we have 2 columns:

"b" which contains a value
"rest" which contains a single column table named "a"

Let's say I want to update the first row of c2, I want to add a new column to the table in the "rest" column.

I tried to construct this new table elsewhere like this and it worked well:

AddColumns(First(c2).rest, "test", true)

But when I want to apply the changes to c2 with Patch it doesn't work:

Patch(c2, First(c2), {b:-1, rest:AddColumns(First(c2).rest, "test", true)})

Event stranger, I can change the "b" column value without any problem. So there is probably something I am missing with tables. Could anyone explain me what I don't understand here? Why is the table not changed in c2 collection?

Thanks

All responses (3)

Answers (1)

RandyHayes 76,287 Super User 2024 Season 1 on at

Like (0)

Report

Re: Strange behaviour with Patch, AddColumns and nested tables

@MichaB12

Yes, that is exactly what to do. You need to define the schema from the very start. Note that this is relevant to "modifying" an existing table. You can derive new tables from existing with modified column - this is what shaping data is all about. But, once you define the schema, it is what is referenced and used - and "set".
MichaB12 89 on at

Like (1)

Report

Re: Strange behaviour with Patch, AddColumns and nested tables

Oh I didn't know that... Thanks!

Well with that in mind I managed to add this column at the creation of the main table. I used a groupBy to create this nested table, so I just added the AddColumns before the GroupBy and now I don't need to add this column later 🙂

Thank you for your reply!
Verified answer

RandyHayes 76,287 Super User 2024 Season 1 on at

Like (1)

Report

Re: Strange behaviour with Patch, AddColumns and nested tables

@MichaB12

You cannot change the schema like that in a table column of a collection table. Schema is highly important in PowerApps.

What is it that you are trying to achieve? This is very "programmatic" from what it appears - Keep in mind, PowerApps is modeled after Excel - it is not a development platform.