Re: [Simple-support] Constructor injection problems

[Andrew S. <and...@ti...>]

Hi Simon, Niall,

Thanks for your suggestions. I've tracked it down to null values being
passed to the constructor. Although my fields were annotated with
@Element(required = false), I hadn't realised that my constructor arguments
also had to be annotated with required=false, and this turned out to be the
problem. Perhaps this could be made clearer in the documentation (although
other people may not naturally make this error).

Thanks for your help!

Andrew


> On Wed, Jun 27, 2012 at 1:19 PM, Niall Gallagher <
> gal...@ya...> wrote:
>
>> Is your class an inner class, if so is it static? If it is inner and not
>> static it can be be instantiated. If this is not the problem, send me a
>> test case proving the problem, ill see what the problem is here.
>>
>> On a side note, I really doubt there is a bug here, constructor injection
>> has been very heavily tested in recent releases. Make sure u are using the
>> most recent release.
>>
>> --- On *Mon, 25/6/12, Andrew Spinner <and...@ti...>*wrote:
>>
>>
>> From: Andrew Spinner <and...@ti...>
>> Subject: [Simple-support] Constructor injection problems
>> To: sim...@li...
>> Received: Monday, 25 June, 2012, 9:27 AM
>>
>>
>> Hello, and thanks for this lightweight framework,
>>
>> I'm having some problems with constructor injection for my immutable
>> class.
>>
>> My instance variables are all final, and are all serialised by Simple.
>> However, I don't need all the fields to be deserialised - some of the
>> fields are derived, being based on mathematical calculations of the other
>> fields. These derived variables are set in the constructor, based on the
>> parameters passed to the constructor.
>>
>> It doesn't make logical sense to pass values of these derived variables
>> into the constructor, because they're not needed, and will be discarded.
>> However, I've got to do so, or I'll get a ConstructorException, saying "no
>> constructor accepts all read only values."
>>
>> This isn't my production code, just an example:
>>
>> public class calc
>> {
>> @Element(name="number")
>> private final int number;
>> @Element(name="numberSquared")
>> private final int numberSquared;
>>
>> //extra constructor I have to provide
>> public Calc(@Element(name="number") int number,
>> @Element(name="numberSquared") int numberSquared)
>> {
>> this(number); //ignores numberSquared parameter, letting chained
>> constructor calculate value for itself
>> }
>>
>> //usual constructor
>> Calc(int number)
>> {
>> this.number = number;
>> numberSquared = number * number; //ignoring parameter and calculating
>> value for itself
>> }
>>
>> Unfortunately, even when I create this extra constructor, I still get a
>> PersistenceException: "Constructor not matched for class." As far as I can
>> see, I've annotated the constructor correctly, providing a parameter for
>> every possible field.
>>
>> Short of me providing my actual code, is there anything I could look at
>> that might fix it?
>>
>> As a suggestion, it might be useful for PersistenceException to provided
>> more specific information about how the constructor isn't matching.
>>
>> Thanks,
>>
>> Andrew
>>
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