Rollup: SUM(values) but only records that are linked with the current Item

[4N]

Hi everyone. 

I have a table "receipts" that collects receipts linked to different projects. Every receipt can only be linked to one project. The Receipts table has a Number Field "Amount in Euro". 

Now I the Project table, I want to have a Rollup field with the sum of all Amount field. But only those who are linked with the Project im currently in. 

What I want to do is add the condition "Where Project is exactly current project". So for Project 1 it filters by that, for Project 2 by that one. But I can only choose one particular project. 

Am I missing something or is there another way to do this? 
Basically what im trying to do is see the Sum of all incoming and outgoing receipts for every project right within the Project. 

Any helps would be greatly appreciated 🙂 

[TheTimeSavingCo · Accepted solution]

Hm, you shouldn't need to do that since each receipt's linked to the correct project I believe

Here's a base I set up to demonstrate this:

Link to base

[4N]

Ohh... thanks for the quick reply! 

I didn't realise I basically already set that filter by linking the receipts to the projects. Works like a charm now!

[4N]

Adding one question since I'm here already... in my case I'm differentiating between incoming and outgoing receipts and then subtract the sum of incoming from sum of outgoing. So if the result is positive, there was a profit, if its negative, there is a loss. 
Is there any way to color this one particular cell with the result? 
I only found the option to color the whole project row (the little dot in front of the name field) 

[TheTimeSavingCo]

Ahh, at this time I don't think so I'm afraid

[Dan_Montoya]

I would use an automation that sets a field that is a single select.  Profit is green and loss is red