Hi Darren,
I vaguely recall having discussed this on the user group before, but I
cannot seem to find the relevant thread...
The behaviour that you have observed is specified by the
DefaultRecordMapper, which defines the behaviour of all "into(Class)"
methods:
http://www.jooq.org/javadoc/latest/org/jooq/impl/DefaultRecordMapper.html
In the case of java.lang.Long, this rule applies:
If no default constructor is available, but at least one "matching"
constructor is available, that one is used
- A "matching" constructor is one with exactly as many arguments as this
record holds fields
- When several "matching" constructors are found, the first one is
chosen (as reported by
Class.getDeclaredConstructors()<http://java.sun.com/javase/6/docs/api/java/lang/Class.html?is-external=true#getDeclaredConstructors()>
- When invoking the "matching" constructor, values are converted onto
constructor argument types
In the case of java.lang.String, there is a default constructor String(),
which is used, and which explains why you get empty strings as a result.
The primitive type use-case is currently not handled correctly. I wonder if
we should indeed adapt the DefaultRecordMapper in the event of mapping
Record1 types to any "well-known" type (i.e. a type available from
SQLDataType:
http://www.jooq.org/javadoc/latest/org/jooq/impl/SQLDataType.html), or to a
type available from a registered Converter. Certainly, these value-types
shouldn't be handled the same way as POJO types, even if there is no formal
way to distinguish them...
I think we can implement this for jOOQ 3.4:
https://github.com/jOOQ/jOOQ/issues/3212
Note, while it would be possible to pass a primitive type, e.g. as
"fetchInto(int.class)", this would still return a List<Integer> due to the
way generics work. The type of int.class is Class<Integer>:
http://docs.oracle.com/javase/8/docs/api/java/lang/Integer.html#TYPE. The
way jOOQ currently handles primitive types when using type conversion is
that nulls are converted to the initialisation value of the respective
primitive type. E.g. 0 for int, 0.0 for double, false for boolean, etc.
Cheers
Lukas
2014-04-26 16:08 GMT+02:00 Darren S <[email protected]>:
> I ran into a bug in my code because I was using jOOQ wrong, but thought
> maybe it would be nice to fail on this situation.
>
> I wanted to select a single column that was a long and instead of writing
> fetch(TABLE.FIELD), as I should, I wrote fetchInto(Long.class). And it
> worked. So I thought you could just put a primative type for fetchInto().
> Later I wanted to select a string column, so I wrote
> fetchInto(String.class) which does not work. It will just return a blank
> string for every entry. So digging a bit into this I found out that
> fetchInto(primitive type) is not supported but Long just happens to work
> because it has a Long(long) constructor that by coincidences is the first
> constructor returned.
>
> So it might be nice in jOOQ that if somebody passes a primitive type it
> fails or actually handles it.
>
> Darren
>
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