Hi,
The reason you get the error is because linked fields and lookup fields in Baserow are always considered to be lists, even if they only contain one item. I tried to replicate your database structure.
- A table with Ingredients that have a field for the unit cost
- A table with Recipes. Each record in that table has an ingredient. There is only one ingredient for a record. So, I use the rollup function min() or max() to make sure that value is a number and not a list of items. You will notice that the grey background disappears and that the number is aligned to the right side of the field. This indicates that it is a number instead of a list of items
I can now create a formula field that calculates the cost for that ingredient for a certain pizza based on the amount of the ingredient that is needed
- You can create a rollup field with the sum() function from the Pizzas table referring to that formula field
