The ability to filter records based on certain criteria is the only major function still missing from the formula field. Adding this would turn SmartSuite into a fully connected database that can answer all questions we need to ask of it.
The recent expansion of the functions available in the formula field has really levelled up our ability in SmartSuite. The addition of TOP, RELATED_RECORD_SORT and RELATED_RECORDS_SORT allow us to sort linked records based on which information is relevant and display and work with that information.
Adding a similar function to filter records will complete SmartSuite's data retrieval capability to the same level as a formal SQL query. This will allow full flexibility in the data structures we can build and return useful information from.
A potential syntax for this function could be
RELATED_RECORDS_FILTER( [Related Record].[Field to Return], [Related Record].[Field to Filter By], [Field Value], [Filter Type])
where [Filter Type] is the comparison to use in the filter (depending on the field type of the [Field to Filter By] this could be "is", "is_not", "contains" etc*) and [Field Value] is the value to use in the filter.
* note that a complete list of the field types and their allowed filter options already exists for use in the API and is available at https://help.smartsuite.com/en/articles/6963760-sorting-and-filtering-records-in-the-rest-api