DATAREDIS-482 - Provide meaningful exception messages in MappingRedisConverter.

Original pull request: spring-projects#183.

Author: christophstrobl

src/main/java/org/springframework/data/redis/core/convert/MappingRedisConverter.java

@@ -509,6 +509,7 @@ private void writeToBucket(String path, Object value, RedisData sink) {
 }
 
 if (customConversions.hasCustomWriteTarget(value.getClass())) {
+
 Class<?> targetType = customConversions.getCustomWriteTarget(value.getClass());
 
 if (ClassUtils.isAssignable(Map.class, targetType)) {
@@ -521,9 +522,9 @@ private void writeToBucket(String path, Object value, RedisData sink) {
 } else if (ClassUtils.isAssignable(byte[].class, targetType)) {
 sink.getBucket().put(path, toBytes(value));
 } else {
-throw new IllegalArgumentException("converter must not fool me!!");
+throw new IllegalArgumentException(
+String.format("Cannot convert value '%s' of type %s to bytes.", value, value.getClass()));
 }
-
 }
 
 }
@@ -634,7 +635,8 @@ private void writeMap(String keyspace, String path, Class<?> mapValueType, Map<?
 
 Matcher matcher = pattern.matcher(entry.getKey());
 if (!matcher.find()) {
-throw new RuntimeException("baähhh");
+throw new IllegalArgumentException(
+String.format("Cannot extract map value for key '%s' in path '%s'.", entry.getKey(), path));
 }
 String key = matcher.group(2);
 target.put(key, fromBytes(entry.getValue(), valueType));
@@ -665,7 +667,8 @@ private void writeMap(String keyspace, String path, Class<?> mapValueType, Map<?
 
 Matcher matcher = pattern.matcher(key);
 if (!matcher.find()) {
-throw new RuntimeException("baähhh");
+throw new IllegalArgumentException(
+String.format("Cannot extract map value for key '%s' in path '%s'.", key, path));
 }
 String mapKey = matcher.group(2);