It used to work. What happened?

Why does it work with a simple date, but not with a date in an array?


Cannot convert value to the specified format?


Thanks for your help!

Hi @11177 ,
it’s a matter of datatype: adding days to a Date rather than to a List.

You can easily change this behaviour if you add .First() in the III (2) Formula Date column (assuming you’ll always have a single date): is this your case?

Otherwise, you should iterate through the list and add the days for every item.

I hope this helps. Let me know otherwise.


Hi @Federico.Stefanato !

Thank you so much for responding to my request for help!

I tried this option - it didn’t help or I’m doing something wrong.

Here is the document, it will be faster to find the problem:

@Federico.Stefanato can you give me some advice please? What can be done?

@11177 ,

this works partly: thisRow.PreviousRow1.split(",").Left(-8)` and the column as text. as far as I can see you have different data sources and the result is data in different formats giving you trouble. Go back to the source, align the formats and you might be set.

best, christiaan

1 Like

Your III (2) column is a Lookup column, meaning it is NOT a date — it’s an object (a ROW reference). You cannot add days to an object. The fact that it shows the date for your has nothing to do with it — the object has a designated property to show as it’s “summary” (for table that’s the column selected as Display Column).

I imagine the columns is something like a “previous day row” lookup or something. You need to get the actual DATE value from that record, e.g. by adjusting the formula in your III (2) column to read Table.Filter(...).First().Date or whatever your date column is named.


@11177 my apologies for being unresponsive.
I hope that @Paul_Danyliuk (thank you!) clarified the issue with his comprehensive answer.


1 Like

Thank you so much for your help! As an option, this solution works. I want to figure out how to correctly translate an object into a simple date.

@Paul_Danyliuk Thank you so much for your help!
“You cannot add days to an object.” - I understand that.
That’s why I’m trying to convert the object to a date.But it doesn’t work.

Here’s an example: a column is partly converted to clean date (not object) and partly not.


What could be the reason for this result?

@Federico.Stefanato I hope I’m not distracting you too much.
The thing is, everything worked correctly for me before - there were no problems.

Hi @11177,
you’re not distracting me at all. I just wish I could have some more time :slight_smile:

I asked for document permission di dig deeper.
However, form what I see, it’s likely a matter of date localisation issue.

You might want to convert the date in the American format (MM/DD/YYYY) and afterwards setting your preferred date format (in the column settings).

Let me know if this makes sense to you.
In the meantime, I’ll be waiting to see the document.

Thank you!

1 Like

DON’T convert like that.

As I said, don’t just attempt to convert an object ToDate(). Instead take the column that you need, e.g.

PreviousRow1.First().[Date of purchase]

The fact that it worked before is purely coincidental — doesn’t mean that you were doing it right before.

Oh, and yeah. Setting a column to type Date does NOT change the values calculated into that column by a formula. It merely hints Coda to try format values there as dates. The value is always of the type that you’ve calculated there. If you’ve calculated a list of rows from a Table.Filter(...), then regardless of what column type you choose, the value there will still be a “list of rows from table Table”.

1 Like

Hi @11177 ,
thanks for sharing the document.

For what I have seen, the issue relies mainly in the Дата изготовления's formula column, where you explicitly converted the lookup type into DateTime.

This is the point: you can’t.
There can be some cases where the conversion might work, but is a side effect of data inference (and definitely an anti-pattern).

Rather, you do can select the date attribute of that object; in this case, thisRow.PreviousRow1.Дата изготовления.

I have the feeling that perhaps the model representation (and its display value) could be simpler, but I can’t understand the domain due to linguistic barriers and so I can’t really point out any alternative.

Anyway, I hoper that this clarifies.
Do let me know otherwise.



Thank you all for your help!
Especially Federico.Stefanato!

1 Like