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Caz in care IValidatableObject.Validate nu este apelat

Daca in aplicatia voastra MVC in loc de Enterprise library pentru validare o sa fiti surprinsi ca exista cazuri cand metoda pentru validare nu este apelata asa cum v-ati astepta.
Folosind atributele HasSelfValidate si SelfValidate, putem sa validam un obiect. Atributul HasSelfValidate ne spune daca obiectul curent are un mecanism propiu de validare. Metoda care face validarea in interiorul obiectului nostru trebuie sa aibe atributul SelfValidation si urmatorul antet:
void numeMetoda( ValidationResults validationResults )
In cazul in care obiectul nu este valid putem sa adaugam pe validationResults mesajul dorit impreuna cu alte informatii precum: nume propietate si referinta la obiectul care nu este valid.
[HasSelfValidate]
public class Person
{
public int Age { get; set; }

public int Name { get; set; }

[SelfValidation]
public void Validate(ValidationResults validationResults)
{
if( Age < 0 )
{
validationResults.AddResult(new ValidationResult("Varsta este negativa", this, "Age", null,null);
}
if( string.IsNullOrEmpty( Name ) )
{
validationResults.AddResult(new ValidationResult("Numele nu este valid", this, "Name", null,null);
}
}
}
In cazul unei aplicatii MVC clasa noastra o sa aibe forma urmatoare:
public class Person : IValidatableObject
{
[Required]
public int Age { get; set; }

[Required]
public int Name { get; set; }

public IEnumerable[ValidationResult] Validate(ValidationContext validationContext)
{
if( Age < 0 )
{
yield return new ValidationResult("Varsta este negativa", new [] { "Age" });
}
if( string.IsNullOrEmpty( Name ) )
{
yield return new ValidationResult("Numele nu este valid", new[] { "Name"});
}
}
}
Mecanismul este exact la fel ca si cel cu atribute, doar ca implementam o interfata. Am putea spune ca cele doua implementări au același comportament pentru orice caz. Dar din pacate nu este adevarat. Pentru a doua implementare o sa apara cazuri cand metoda noastra de validare nu se apelează.
Daca Age sau Name nu este completat o observam ca metoda Validate nu este apelata. Totul apare din cauza atributului Required, care verifica daca s-a introdus o valoarea pentru propietatea marcata, iar daca valoarea nu a fost introdusa nu o sa apeleze metoda Validate. Acest comportament apare din cauza ca prima data se face validarea propietatiilor in functie de atirbutele cu care sunt decorate, iar doar apoi daca validarea a fost cu succes se apeleaza metoda noastra
Acest caz nu ar trebuii sa ne deranjeze in general. Dar trebe sa il avem in vedere pentru anumite cazuri. De exemplu faca avem o pagina unde un user se inregistreaza si acesta nu introduce numele, dar introduce parola, poate am dorii sa apara un mesaj in care sa ii se spuna ca parola nu este destul de sigura sau ceva asemanator.

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