Adding field validation to support validation of nested models

[allenchen1154]

An issue I encountered when integrating RAVE was boilerplate for dealing with nested models. Let's say I have a class, ModelA, that contains an instance of ModelB. For an instance of ModelA to be considered valid, its instance of ModelB must also be valid.

@Validated(factory = SampleFactory.class)
public class ModelA {
    private ModelB mModelB;

    @MustBeTrue 
    public boolean isModelBValid() { 
        try {
            Rave.getInstance().validate(mModelB);
            return true;
        } catch (RaveException e) {
            return false;
        }
    }
}

@Validated(factory = SampleFactory.class)
public class ModelB {
    // ModelB can have its own arbitrary validation criteria, including nested models
}

There are some issues with the above code:

• This doesn't scale well as ModelA accumulates more nested models. Each one requires its own @MustBeTrue-annotated getter, which must have the same code duplicated.
• Every model class that contains an instance of ModelB must have the same boilerplate.

I think the solution to this issue is to have default, recursive validation of fields. The logic would be something like:

void validate(Object model)
    for field in model:
        if field is supported:
            validate(field)
    // current logic here for validation of additional getters 

[naturalwarren]

RAVE already recursively validates fields but requires a "getter" method for ModelB in order to validate the instance of ModelB contained by ModelA.

If a field is private, as shown in the example above, the generated validator can't access it to perform validation. If a field is package private, the generated validator may not be able to access it unless the validator is in the same package. Having public fields in models is an anti-pattern so we won't concern ourselves with that case.

If we inlined validation logic on a per model basis we could conceivably perform field validation and alleviate the constraint of requiring a public getter method that returns a field in order for that field to be validated. This would require large changes to how RAVE performs validation but is something we should investigate. @behroozkhorashadi what do you think?

[allenchen1154]

So you're saying that in the above code, the same result would be achieved by replacing the @MustBeTrue public boolean isModelBValid() with a simple getter like

public ModelB getModelB() {
    return ModelB;
}

?

[allenchen1154]

Just found the code after looking in BaseValidator.checkNullable(). Awesome!

I'm not sure what you mean by "inlining validation logic on a per model basis". Could you clarify?