Custom validators not works?

[qarmin]

I have code rest endpoint which takes JSON as argument

#[post("/patients", data = "<new_patient>")]
pub async fn create_patient(
    db: &State<DatabaseConnection>,
    new_patient: Json<NewPatientInfo>,
) -> Result<Json<PatientInfo>, ErrorResponder> 

with field birth date and custom validator

#[derive(Serialize, Deserialize, JsonSchema, FromForm)]
pub struct NewPatientInfo {
    #[field(validate = crate::commons::rocket_validators::date_validator())]
    pub(crate) birth_date: String,

Validator is simple(and useless), but not works - there is no SSSSS in output

pub fn date_validator<'v>(str_date: &str) -> form::Result<'v, ()> {
    println!("SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS");
    Ok(())
}

When I change crate::commons::rocket_validators::date_validator to invalid path, I have compilation error, so I'm sure that this points to correct function, but still I don't know why this not works

[SergioBenitez]

The field struct field attribute is used by the FromForm derive. If you were to accept a Form<NewPatientInfo>, the validation routine would run. Instead you're accepting a Json, which uses Deserialize. If you need extra validation for fields, you'll need to go through serde.