Re: Throw Exception when retrieving non-existing Field in Response

[Christofer Dutz]

Hi Julian,

I agree that we should throw an exception.

Chris



Am 31.10.18, 21:25 schrieb "Julian Feinauer" <j.feina...@pragmaticminds.de>:

    Hi all,
    
    I found some time today to test and toy around a bit with PLC4X and I 
discovered a behavior which I found weird.
    I had the response from a request which “failed” (Response was successful 
but the Field I wanted was NOT_FOUND).
    So my response.getLong(“…”) returned a “null” and a subsequent implicit 
cast to long finally led to a NPE.
    
    My expected behavior would be an Exception (Runtime Exception).
    Also in the case when I try to fetch a filed which is non-existent.
    Currently we return null in both cases (see snippet from 
DefaultPlcReadResponse):
    
    private BaseDefaultFieldItem getFieldInternal(String name) {
        // If this field doesn't exist, ignore it.
        if (values.get(name) == null) {
            return null;
        }
        if (values.get(name).getKey() != PlcResponseCode.OK) {
            return null;
       }
        return values.get(name).getValue();
    }
    
    I suggest to throw a Runtime Exception in both cases to give a “valid” 
Error Message instead of a NPE which is totally unexpected.
    
    Is this okay for everybody? Or are there any concerns?
    
    Julian