BeanPurée is a middle layer between JavaBeans and shapeless.

NOTE: The library is in active development stage. So the API might be changed.

Even though Scala is compatible with Java, the languages are different, and the coding styles are different too. In Scala we prefer to use immutable case classes, but in Java world mutable JavaBeans are common building blocks. Moreover, many Scala libraries provide API which requires case classes (e.g. different serializers). As result, we need to have similar model classes for Java and Scala. This library helps to convert data between JavaBeans and case classes.

BeanPurée is available for Scala 2.10, 2.11 and 2.12. Currently there is no release version. Adding in sbt:

libraryDependencies += "me.limansky" %% "beanpuree" % "0.1"

If you'd like to use development version:

resolvers += Resolver.sonatypeRepo("snapshots")

libraryDependencies += "me.limansky" %% "beanpuree" % "0.2-SNAPSHOT"

The core of BeanPurée is BeanGeneric class, which have a same role with shapeless Generic, but for JavaBeans. Assume we have class:

public class Foo {
    private int a;
    private String b;

    public int getA() { return a; }
    public void setA(int a) { this.a = a; }

    public String getB() { return b; }
    public void setB(String b) { this.b = b; }

    public String toString() {
        return "Foo(" + a + ", \"" + b + "\")";
    }
}

Now we can create BeanGeneric instance and convert bean to HList and backward:

scala> val gen = BeanGeneric[Foo]
gen: me.limansky.beanpuree.BeanGeneric[Foo]{type Repr = shapeless.::[Int,shapeless.::[String,shapeless.HNil]]}

scala> val foo = gen.from(5 :: "aaa" :: HNil)
foo: Foo = Foo(5, "aaa")

scala> foo.setB("changed")

scala> gen.to(foo)
res2: gen.Repr = 5 :: changed :: HNil

Another important thing is LabelledBeanGeneric, which is a LabelledGeneric adopted for the beans. It's important to note, that it uses "field names" generated from the getters names. E.g. getStartTime become startTime and isEven become even.

The next thing is a BeanConverter class. It uses LabelledBeanGeneric and LabelledGeneric to convert between beans and case classes.

scala> case class Bar(a: Int, b: String)
defined class Bar

scala> val conv = BeanConverter[Foo, Bar]
conv: me.limansky.beanpuree.BeanConverter[Foo,Bar] = me.limansky.beanpuree.BeanConverter$$anon$1@4eae0bc5

scala> conv.beanToProduct(foo)
res3: Bar = Bar(5,changed)

scala> conv.productToBean(Bar(15, "bar"))
res4: Foo = Foo(15, "bar")

BeanConverter doesn't care about fields order, but requires to have all the same fields with the same types. It also mean that if the bean uses Java numeric classes (like java.lang.Integer), the case class also should have the field with Java class.