The following example shows a custom function call within a table query. It filters the data displayed by a Show Table page for the Products table that’s in the Northwind database, and shows only product records that have an “on order” level that exceeds 65 units.
This code is inserted into the Show Products Table page’s customizable class at the end of the ShowProductsTable class (this is the first class of three class definitions in the file).
' returns the maximum On Order level currently allowed
Public Shared Function MaxOnOrderLevel() As String
' (For simplicity, this function simply returns a hard-coded value.
' In a "real-world" application, this value would probably be
' calculated dynamically by some external process.)
' Maximum On Order level is sixty-five units
Return "65"
End Function
Note this function can actually be added anywhere in the project that’s accessible by the Show Table Page’s classes. In this case, the custom function is a shared method on the Show Table Page’s customizable class.
In Iron Speed Designer, a query selection criteria (WHERE clause) is added that selects records that have a UnitsOnOrder level greater than the custom function ShowProductsTable.MaxOnOrderLevel().
Products.UnitsOnOrder > ShowProductsTable.MaxOnOrderLevel()
Calling Custom Code Functions in WHERE Clauses
Example: Calling a .NET Framework Function
Example: Calling a Custom Function in a Customizable Class