How to add a value in the tabular part 1s by code?

Question

1C

I have a Book Lease document, there is a tabular part, you need to put the CurrentDate() + 7 days into it in the attribute of the tabular part PlannedReturnDate.
Tried like this

&НаКлиенте
Процедура ДеталиКнигаПриИзменении(Элемент)
  
  Элементы.Детали.ПлановаяДатаВозврата = ТекущаяДата() + 7 * 86400;
  
КонецПроцедуры

Answer 1

Try this:
Items.Details.CurrentData.PlannedReturnDate = CurrentDate() + 7 * 86400;

Answer 2

The tabular part is LINES!!!!
those. you need to decide which line it will be written to

Answer 3

You are trying to assign a value not to what you need, and the wrong place has been chosen.
See, for example, here https://oficcer.ru/windows-7/zapolnyaem-tablichnuy... the section "How to programmatically fill in the details of a tabular section row"

Answer 4

You need to determine the current line and work with it already.