Give more helpful error message when an invalid alias is encountered #205
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| @@ -117,7 +117,7 @@ public Object decode(String alias, U value) { | |||
| if (encoder != null) | |||
| return encoder.decode(value); | |||
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| throw new TypeDecodingException("An unknown alias [" + value + "] was encountered"); | |||
| throw new TypeDecodingException("An unknown alias [" + alias + "] was encountered while decoding value [" + value + "]. Valid aliases are " + String.join(", ", aliasMapping.keySet())); | |||
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Two problems with this.
- We shouldn't assume that the value is easily representable as a string. There are instances for example where byte[] are used instead of strings. These will print out as a cryptic error message. That being said the error message was incorrectly using the value instead of the alias.
- String.join is a java 8 method. Mango is compatible to Java 6 to work with older applications in production.
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- Trying toString sounds better than nothing. Maybe it'll confuse the issue by printing garbage, but maybe it'll be helpful for figuring out what data was being processed when this problem was encountered.
- Mango uses the diamond operator all over the place, and that requires 1.7. I'll rewrite to use guava's Joiner instead.
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Yes, but printing the value doesn't add anything to the value of the error message when the alias is the reason for the exception so lets not do that. If the exception was from the act of decoding then yes it would potentionally make sense to try to show something about the value.
Oops, I meant Java 7. Guava Joiner is fine.
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The current error message when an invalid alias is passed in is misleading. I revised it to make it more user-friendly.