Reading a byte array from couchbase in Spring - spring

Question

I have a simple Object that I am trying to read/write into couchbase (using spring data).
Here is the object:
#Document
public class CacheObject {
#Id
private String id;
private byte[] data;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public byte[] getData() {
return data;
}
public void setData(byte[] data) {
this.data = data;
}
}
I try to read/write it using the Couchbase template:
#Test
public void test2() throws Exception {
CacheObject o = new CacheObject();
o.setId("test1");
o.setData("test123".getBytes());
CouchbaseTemplate t = c.couchbaseTemplate();
t.save(o);
CacheObject o2 = t.findById("test1", CacheObject.class);
System.out.println("COOL " + new String(o2.getData()));
}
The template comes from a config that extended AbstractCouchbaseConfiguration.
The write works fine, I see the base64 encoded value in couchbase.
The read throws an Exception:
org.springframework.core.convert.ConversionFailedException: Failed to convert from type java.lang.String to type byte for value 'd293'; nested exception is java.lang.NumberFormatException: For input string: "d293"
at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:41)
at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:189)
at org.springframework.core.convert.support.StringToArrayConverter.convert(StringToArrayConverter.java:63)
at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:35)
...
I can get around this by using a custom reader (This is in my config that extended AbstractCouchbaseConfiguration). Using this code, everything works.
public CustomConversions customConversions() {
return new CustomConversions(Arrays.asList(StringToByteConverter.INSTANCE));
}
#ReadingConverter
public static enum StringToByteConverter implements Converter<String, byte[]> {
INSTANCE;
#Override
public byte[] convert(String source) {
return Base64.decodeBase64(source);
}
}
Am I doing something wrong?
I have tried 1.2.2 and 1.3.0.M1 and both give the same results.
Thanks

Answer 1

I think you are doing this correctly. If you observe the json that got stored in Couchbase, it looks like this:
{
"_class": "CacheObject",
"data": "dGVzdDEyMw=="
}
When you try to convert the data property back to a CacheObject, it is attempting to convert the string above to a primitive byte array, hence the NumberFormatException. Is there something you are trying to accomplish by storing a byte array the way you are doing it?
According to the approach you are testing, I think you need a custom converter to transform the string version of the byte array as expected, because couchbase template doesn't support this type by default. See this link for supported types:
http://docs.couchbase.com/developer/dev-guide-3.0/using-json-docs.html
Hope this helps.