Re: [bv-dev] Bean Validation and JavaFX

2012/7/1 Emmanuel Bernard <emmanuel(a)hibernate.org&gt;: Do you have some more details on that? Today BV is focused on actual Java types adhering to the JavaBeans convention (types with getters/setters), but there are use cases where one may have another type model but still would like to use the BV validation approach. My thinking was to provide an SPI which allows to customize the way BV interacts with type models. This SPI would establish an abstract type model used by the BV runtime. This model would know about "types", "properties" and so on, but these wouldn't necessarily have to be actual Java types with bean properties. The default implementation of course would be based on JavaBeans as today, but one could plug-in implementations based on other models, too. One example is a dynamic model like DynaBeans [1] (or e.g. dynamic EMF models [2]). Here "types" are defined at run-time like this: DynaProperty[] props = new DynaProperty[]{ new DynaProperty("address", Map.class), new DynaProperty("lastName", String.class) }; BasicDynaClass employeeType = new BasicDynaClass("employee", null, props); DynaBean employee = employeeType.newInstance(); employee.set("address", new HashMap()); employee.set("lastName", "Flintstone"); As of today, you can't apply constraints to the "employee" type, though, as it is no JavaBean. In such a case constraints could e.g. be declared using an API (example based on HV's constraint API): ConstraintMapping mapping = new ConstraintMapping(); mapping.type( new DynaBeansTypeIdentifier ( employeeType ) ) .property( "address" ) .constraint( new NotNullDef() ) .valid() .property( "lastName" ) .constraint( new NotNullDef() ) .constraint( new SizeDef().min( 2 ).max( 14 ) ); The SPI would provide a way for declaring constraints (see above) and functionality used by the BV runtime to navigate over validated types and retrieve the required type meta data for validation. Coming back to JavaFX, there the Employee type could look like this: public class Employee { @NotNull @Valid private final ObjectProperty<Map> address = new SimpleObjectProperty<Map>(this, "address"); @NotNull @Size(min=2, max=14) private final StringProperty lastName = new SimpleStringProperty(this, "lastName"); ... } As of today, the annotations would be of no effect, as there are not validators such as SizeValidator<Size, StringProperty>. But using the SPI, one could hook in an adapter which creates a representation of the Employee type in the abstract model (with e.g. the "lastName" property being of type String), which would allow the BV runtime to operate on it. That said, I'm aware of that this would probably be a large addition, and I'm not sure whether it would be doable at all. For the JavaFX case, also this solution would be imaginable: public class Employee { private final StringProperty lastName = new SimpleStringProperty(this, "lastName"); @NotNull @Size(min=2, max=14) public String getLastName() { return lastName.get(); } public void setLastName(String lastName) { this.lastName.set( lastName ); } public StringProperty nameProperty() { return name; } ... } That's much wordier than annotating the actual properties, though. --Gunnar [1] http://commons.apache.org/beanutils/api/org/apache/commons/beanutils/pack... [2] http://www.devx.com/Java/Article/29093/1763/page/2