xamarin
Objektvalidierung durch Anmerkungen
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Einführung
mvc.net führt Datenanmerkungen zur Modellvalidierung ein. Dies kann auch in Xamarin gemacht werden
Einfaches Beispiel
Fügen Sie das Nuget-Paket System.ComponentModel.Annotations
Definiere eine Klasse:
public class BankAccount
{
public enum AccountType
{
Saving,
Current
}
[Required(ErrorMessage="First Name Required")]
[MaxLength(15,ErrorMessage="First Name should not more than 1`5 character")]
[MinLength(3,ErrorMessage="First Name should be more than 3 character")]
public string AccountHolderFirstName { get; set; }
[Required(ErrorMessage="Last Name Required")]
[MaxLength(15,ErrorMessage="Last Name should not more than 1`5 character")]
[MinLength(3,ErrorMessage="Last Name should be more than 3 character")]
public string AccountHolderLastName { get; set; }
[Required]
[RegularExpression("^[0-9]+$", ErrorMessage = "Only Number allowed in AccountNumber")]
public string AccountNumber { get; set; }
public AccountType AcType { get; set; }
}
Definieren Sie einen Validator:
public class GenericValidator
{
public static bool TryValidate(object obj, out ICollection<ValidationResult> results)
{
var context = new ValidationContext(obj, serviceProvider: null, items: null);
results = new List<ValidationResult>();
return Validator.TryValidateObject(
obj, context, results,
validateAllProperties: true
);
}
}
Verwenden Sie den Validator:
var bankAccount = new BankAccount();
ICollection<ValidationResult> lstvalidationResult;
bool valid = GenericValidator.TryValidate(bankAccount, out lstvalidationResult);
if (!valid)
{
foreach (ValidationResult res in lstvalidationResult)
{
Console.WriteLine(res.MemberNames +":"+ res.ErrorMessage);
}
}
Console.ReadLine();
Ausgabe generiert:
First Name Required
Last Name Required
The AccountNumber field is required.
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