Creating Custom Functions Using Name Conventions¶
We recommend developing custom functions using annotations. However, it is also possible to do it following certain conventions for the name of the class and its methods.
In order to make a Java class recognizable as a custom function, the name of the class has to match the following rules:
<FunctionName>VdpFunctionfor condition functions<FunctionName>VdpAggregateFunctionfor aggregation functions
Note
These conventions are case sensitive. That means that the name of
the class has to be like function1VdpFunction and not
function1VDPFUNCTION.
This way a Java class named Concat_SampleVdpFunction will be
interpreted as a condition function named Concat_Sample; and a class
named Group_Concat_SampleVdpAggregateFunction, as an aggregate
function named Group_Concat_Sample.
All Java methods implementing the function signatures must have the name
execute. The signature associated with each method will be extracted
from its method parameters.
For example, a class named Concat_SampleVdpFunction with a method
execute(valueA:String, valueB:String):String will generate the
function signature CONCAT_SAMPLE(arg1:text, arg2:text).
The way to define an arity n in a custom function is with an array as
the last parameter in the method. I.e. a class
Concat_SampleVdpFunction with a method declared as
public String execute(String [] inputs).
A custom function has to define a method named executeReturnType
with the same parameters as the associated execute method if:
The return type of the function is an array or a register.
Or, the return type of the function depends on the type of the input parameters.
See the section Custom Function Return Type for more details about this method.