Validation when the setter is invoked?

peter_v · **Joined:** Wed Jan 16, 2008 8:23 am **Posts:** 7

Hi,

I want to apply validation rules to our business objects, and since it makes sense to report problems to the caller as soon as possible (instead of waiting until they have assembled the whole object), I would like to invoke each single-property validator (e.g. @NotEmpty) when the setter of that property is called.

I don't want an AOP proxy just for this, I'm OK with triggering the validation manually from the setter, but I'd to use Hibernate Validator's annotations.

Examples:

Code:

// Version 1: looks nice, but the validation doesn't get invoked when the setter is called.
@NotEmpty
public String getName() { 
    return name;
}

public String setName(String name) {
    this.name = name;
}

Code:

// Version 2: the validation takes place instantly, but it doesn't use the Hibernate Validator framework.
public String getName() { 
    return name;
}

public String setName(String name) {
    if (name == null || name.length() == 0) {
        // report problem
    }
    this.name = name;
}

Code:

// Version 3: I need something like this
@NotNull
public String getName() { 
    return name;
}

public String setName(String name) {
    // Run validation based on object type, property name & property value
    ValidatorManager.validate(this.getClass(), "name", name);
    this.name = name;
}

How can I do this?

Thanks,
Peter

hardy.ferentschik · **Posted:** Tue Jan 29, 2008 3:43 pm

I think you can achieve your version three by using Application-level validation. Check the Hibernate Validator documentation for it.

http://www.hibernate.org/hib_docs/validator/reference/en/html_single/#d0e436

emmanuel · **Posted:** Thu Jan 31, 2008 1:01 pm

I don't like the idea of polluting the domain model with the validator code.

I'd rather use

Code:

ClassValidator addressValidator = new ClassValidator( Address.class, ResourceBundle.getBundle("messages", Locale.ENGLISH) );

//only get city property invalid values
InvalidValue[] validationMessages = addressValidator.getInvalidValues(address, "city");

//only get potential city property invalid values
InvalidValue[] validationMessages = addressValidator.getPotentialInvalidValues("city", "Paris")

when the client is called. That is what Seam is doing.