Fix null element handling in array bind parameters (#1692)

PgParamDesc.prepare() applied the array element type's preEncoder function unconditionally to every array element, including nulls. For NUMERIC[] parameters this causes prepareNumeric() to be invoked on a null element, and the bound query never completes.

Skip the preEncoder call for null elements so they are preserved as SQL NULL, matching how non-array parameters already handle null.

Closes #1690

Signed-off-by: adityaanikam <adityanikam9502@gmail.com>

Author: adityaanikam

vertx-pg-client/src/main/java/io/vertx/pgclient/impl/codec/PgParamDesc.java

@@ -69,7 +69,7 @@ public TupleBase prepare(TupleBase values) {
             Object[] array = (Object[]) val;
             Object[] tmp = new Object[array.length];
             for (int j = 0;j < array.length;j++) {
-              tmp[j] = preparator.apply(array[j]);
+              tmp[j] = array[j] == null ? null : preparator.apply(array[j]);
             }
             val = tmp;
           } else {

vertx-pg-client/src/test/java/io/vertx/tests/pgclient/data/NumericTypesExtendedCodecTest.java

@@ -535,6 +535,16 @@ public void testNumericArrayToBigDecimalArrayRowConverter(TestContext ctx) {
       (row, index) -> row.get(BigDecimal[].class, index));
   }
 
+  @Test
+  public void testNumericArrayToBigDecimalArrayRowConverterWithNullElement(TestContext ctx) {
+    BigDecimal[] expected = {new BigDecimal("2.22"), null, new BigDecimal("3.33")};
+    testGetter(ctx,
+      "SELECT c FROM (VALUES ($1 :: NUMERIC[])) AS t (c)",
+      Collections.singletonList(Tuple.tuple().addValue(expected)),
+      new BigDecimal[][]{expected},
+      (row, index) -> row.get(BigDecimal[].class, index));
+  }
+
   @Test
   public void testShortArray(TestContext ctx) {
     testGeneric(ctx,