Null field will lead to "java.lang.IllegalArgumentException: null"

[radiumweilei]

Hi,

Dalesbred is an elegant light-weigth JDBC framework, I use it on my project, and database is mysql, when I query data from table via findAll() method I encounter "java.lang.IllegalArgumentException: null" if there is null field on the return row, hope that we can fix this issue as soon as possible. Thx.

java.lang.IllegalArgumentException: null
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_25]
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_25]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_25]
at java.lang.reflect.Constructor.newInstance(Constructor.java:408) ~[na:1.8.0_25]
at org.dalesbred.internal.instantiation.ReflectionInstantiator.instantiate(ReflectionInstantiator.java:62) ~[dalesbred-1.2.2.jar:na]
at org.dalesbred.internal.result.InstantiatorRowMapper.mapRow(InstantiatorRowMapper.java:76) ~[dalesbred-1.2.2.jar:na]
at org.dalesbred.result.RowMapper.lambda$list$22(RowMapper.java:59) ~[dalesbred-1.2.2.jar:na]
at org.dalesbred.result.RowMapper$$Lambda$40/852687460.process(Unknown Source) ~[na:na]
at org.dalesbred.Database.lambda$executeQuery$1(Database.java:287) [dalesbred-1.2.2.jar:na]
at org.dalesbred.Database$$Lambda$41/951880373.execute(Unknown Source) ~[na:na]
at org.dalesbred.transaction.DefaultTransaction.execute(DefaultTransaction.java:53) ~[dalesbred-1.2.2.jar:na]
at org.dalesbred.transaction.DefaultTransactionManager.withNewTransaction(DefaultTransactionManager.java:61) [dalesbred-1.2.2.jar:na]
at org.dalesbred.transaction.AbstractTransactionManager.withTransaction(AbstractTransactionManager.java:62) [dalesbred-1.2.2.jar:na]
at org.dalesbred.Database.withTransaction(Database.java:201) [dalesbred-1.2.2.jar:na]
at org.dalesbred.Database.withTransaction(Database.java:190) [dalesbred-1.2.2.jar:na]
at org.dalesbred.Database.withTransaction(Database.java:162) [dalesbred-1.2.2.jar:na]
at org.dalesbred.Database.withCurrentTransaction(Database.java:264) [dalesbred-1.2.2.jar:na]
at org.dalesbred.Database.executeQuery(Database.java:278) [dalesbred-1.2.2.jar:na]
at org.dalesbred.Database.findAll(Database.java:325) [dalesbred-1.2.2.jar:na]
at org.dalesbred.Database.findAll(Database.java:333) [dalesbred-1.2.2.jar:na]
at test.TestDalesbred.main(TestDalesbred.java:51) [main/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_25]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_25]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_25]
at java.lang.reflect.Method.invoke(Method.java:483) ~[na:1.8.0_25]
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144) [idea_rt.jar:na]

[komu]

Based on the stacktrace, I'm pretty sure that you have a constructor that requires a primitive value, but null is returned from database and therefore the constructor throws (or rather the reflection machinery trying to invoke the constructor throws).

So the same thing without Dalesbred:

public class Foo {
    public Foo(int x) { }

    public static void main(String[] args) throws Exception {
        Foo.class.getConstructors()[0].newInstance(new Object[] { null });
    }
}

Of course you'll achieve a similar result even without reflection by saying: new Foo((Integer) null).

So if constructor requires non-null value, but Dalesbred only has a null, what should it do? Isn't throwing an exception the only reasonable thing to do?

So either create a constructor that allows null values (e.g. requiring Integer instead of int or something similar) or you coalesce or similar in the database so you don't get a null back int he first place.

If I'm completely wrong about this, then I'm going to need some more details (example source code) to reproduce the bug.

[radiumweilei]

Thanks Komu, I can fix this issue after follow your advice by use primitive wrapper class to instead of primitive data type, that a good news, Thank you very much.