Question

i have an email field
which i want to validate that it’s valid email, and validate that it doesn’t exist in the database, so i used for valid email pattern the @Email from hibernate in the bean:

@NotBlank(message = "{email.required}")
@Email(message = "{invalid.email}")
@Size(max = 25, message = "{long.value}")

and in the jsf page:

<f:validator binding="#{emailExistValidator}" />

my questions:

1. What happens first, the faces validator or the bean validation ?
2. What do you think about this mixing between bean validation and
   FacesValidator, is it bad practice,if so what do you suggest ?

Answer 1

1- What happens first, the faces validator or the bean validation?

JSF conversion and validation will run first in the order it is been declared on the component, with required first. If any of it fails, then the remnant of JSF validation and all the bean validation is completely skipped, else all of the bean validation is executed.

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2- What do you think about this mixing between bean validation and FacesValidator, is it bad practice, if so what do you suggest?

Hard to answer. It solely depends on the functional requirements and the purpose of the validator and how closely tied the validation is to the model or the view.

If the validation needs to run everytime the model property is set (so, it’s closely tied to the model), then bean validation would be preferred. But if validation needs to run only once, e.g. during registration (so, it’s closely tied to a specific view), then JSF validation would be preferred.

For example, if you’re checking the email syntax pattern, then bean validation would make more sense, e.g.:

@Pattern(regexp = "([^.@]+)(\\.[^.@]+)*@([^.@]+\\.)+([^.@]+)", message = "Email is not in valid format")
private String email;

If you’re checking the email existance against the DB, then a JSF validator would make more sense since you don’t want it to unnecessarily be executed on every property set. DB calls are not cheap per se.

Again, this is subjective. See what fits the business requirements the best. Maybe you’re required to validate it on every property set, for example.