Define predetermined input variables for a chart / dashboard

Would be great if we could define "variables" (as input boxes) for a chart and dashboard that can then be used inside the aggregation query filter within the charts. For example - The user enters a UPC to an input box, we take that and convert it to something like: [{$match: {upc: /\d{0,6}$UPC$\d{0,6}/}}] This allows for better exposure of charts across the organization