WW-5828 Bound integer digits when formatting BigDecimal (6.x)

core/src/main/java/com/opensymphony/xwork2/conversion/impl/StringConverter.java

@@ -47,6 +47,16 @@ public class StringConverter extends DefaultTypeConverter {
      */
     private static final int MAX_FRACTION_DIGITS = 340;
 
+    /**
+     * Upper bound on the number of integer digits emitted when formatting a number.
+     * <p>
+     * Covers every {@code double} value in full - the widest is {@link Double#MAX_VALUE}
+     * at 309 integer digits. A {@link BigDecimal} wider than this is rendered by
+     * {@link BigDecimal#toString()} instead, so the length of the output follows its
+     * precision rather than its scale.
+     */
+    private static final int MAX_INTEGER_DIGITS = 340;
+
 
     @Override
     public Object convertValue(Map<String, Object> context, Object target, Member member, String propertyName, Object value, Class toType) {
@@ -92,6 +102,9 @@ public Object convertValue(Map<String, Object> context, Object target, Member me
     }
 
     protected String convertToString(Locale locale, Object value) {
+        if (value instanceof BigDecimal && integerDigits((BigDecimal) value) > MAX_INTEGER_DIGITS) {
+            return value.toString();
+        }
         if (Number.class.isInstance(value)) {
             NumberFormat format = NumberFormat.getNumberInstance(locale);
             format.setGroupingUsed(false);
@@ -109,4 +122,8 @@ protected String convertToString(Locale locale, Object value) {
         }
     }
 
+    private static long integerDigits(BigDecimal value) {
+        return (long) value.precision() - value.scale();
+    }
+
 }

core/src/test/java/com/opensymphony/xwork2/conversion/impl/StringConverterTest.java

@@ -115,6 +115,36 @@ public void testBigDecimalFractionDigitsAreBounded() throws Exception {
         assertEquals("0", value);
     }
 
+    public void testBigDecimalIntegerDigitsAreBounded() {
+        // given
+        StringConverter converter = new StringConverter();
+        Map<String, Object> context = createContextWithLocale(new Locale("pl", "PL"));
+
+        // when the number of integer digits is within the bound
+        Object value = converter.convertValue(context, null, null, null, new BigDecimal(BigInteger.ONE, -339), null);
+
+        // then the value is rendered in full
+        assertEquals("1" + StringUtils.repeat('0', 339), value);
+
+        // when the number of integer digits exceeds the bound
+        value = converter.convertValue(context, null, null, null, new BigDecimal(BigInteger.ONE, -340), null);
+
+        // then the value is rendered in its compact form rather than padded out to its scale
+        assertEquals("1E+340", value);
+
+        // when the scale is far beyond the bound
+        value = converter.convertValue(context, null, null, null, new BigDecimal(BigInteger.ONE, -100_000), null);
+
+        // then the length of the output is bounded by the converter, not by the scale of the value
+        assertEquals("1E+100000", value);
+
+        // when the scale sits at the edge of its range
+        value = converter.convertValue(context, null, null, null, new BigDecimal(BigInteger.ONE, Integer.MIN_VALUE + 1), null);
+
+        // then the bound still applies
+        assertEquals("1E+2147483647", value);
+    }
+
     public void testStringArrayToStringConversion() {
         // given
         StringConverter converter = new StringConverter();