#1726 Support FUNCTION RETURNS ... ARRAY for Java functions

[Ondrej Zizka]

Seems HSQLDB doesn't support custom Java functions returning arrays.

I implemented a couple of JSON supporting functions to bridge the two functionalities (JSON and ARRAY), only to find that the "signature was not found" if the return type is String[] and the FUNCTION RETURNS LONGVARCHAR ARRAY.
(I have also tried with VARCHAR, with a custom defined type etc).

Example of use case: Extract elements from an JSON array of subtrees, and work with that further using array SQL functions.

Until this is implemented, it would also be nice if attempts to create a function which returns ARRAY would fail with a hint that it is not suported, rather than saying the signature is not found.

    // Kotlin code, but an equivalent of Java's String[] - checked in javap
        @JvmStatic fun simpleArray(): Array<String> = arrayOf("a", "b", "c")


  // SQL (works when return type is just VARCHAR)
     CREATE FUNCTION simpleArray()
                        RETURNS VARCHAR ARRAY
                        LANGUAGE JAVA PARAMETER STYLE JAVA
                        EXTERNAL NAME 'CLASSPATH:${javaClass.name}.simpleArray'

Thanks for considering.

[Fred Toussi]

Thanks for reporting. Fixed and committed to SVN.
A usage example is in SVN /base/trunk/src/org/hsqldb/test/TestRoutines.java
Please build the jar and test and report the result.