If you commonly generate invoice items from project hours, you may want to create a column in your invoice for the date of the original project hours entry that generated the invoice item.
One caveat to consider is that, in Clientary , an invoice item may come from multiple project items collapsed into one line item.
The set of project hours that are associated with an invoice item can be fetched with:
{{ invoice_item.project_items }}
By itself, this isn't very useful for a template because it's a list of items that can't be rendered naturally.
Instead, you can take the first date:
{{ invoice_item.project_items | map: 'date' | first }}
Or, you can combine them, separated by a comma
{{ invoice_item.project_items | map: 'date' | join: ', ' }}
You can even format this date further using Liquid's date filter.