How to allow for "dynamic" inputs and/or fetching data

[machty]

I am working on building a decision graph to determine whether a transaction requires additional review before approval. Our clients want the ability to create rules based on recent purchase statistics. For instance, one client has requested the ability to calculate the median transaction amount from the last 5 purchases and use that "dynamic" value as an input in a Decision Table. While we can compute this request for them and input it into the decision graph, they may later want to adjust the number of purchases considered to 10 or another figure.

Are there effective ways to achieve this? Could this be a use case for Custom Nodes, and if so, how would that function?

One approach I’m considering is to provide the transaction history, limited to the last 50 transactions. Then, for any complex logic, clients could use a JavaScript function to perform statistical calculations. Does this seem like a viable plan?