How to specify that at least one checkbox must be selected? - asp.net-mvc

Question

I would like to use a DataAnnotation Attribute that tells the user that he must select one checkbox of the two following checkbox groups. My model is:
//group T
public bool T0 {get;set;}
public bool T1 {get;set;}
public bool T2 {get;set;}
//group P
public bool P0 {get;set;}
public bool P1 {get;set;}
The user must select at least one of the T properties, and one of the P properties. IS there something that do that on some customized dataannotations or i need to create one from beggining?
Thanks

Answer 1

You may use Fluent Validation
[FluentValidation.Attributes.Validator(typeof(CustomValidator))]
public class YourModel
{
public bool T0 { get; set; }
public bool T1 { get; set; }
public bool T2 { get; set; }
}
public class CustomValidator : AbstractValidator<YourModel>
{
public CustomValidator()
{
RuleFor(x => x.T0).NotEqual(false)
.When(t => t.T1.Equals(false))
.When(t => t.T2.Equals(false))
.WithMessage("You need to select one");
}
}

Answer 2

Here 2 solutions you can choice anyone to use.
1.Use action rule:
a) Set “False” as the check box’s default value.
b) Add following action rule to that check box field.
If check_box_field = “False”
Set check_box_field (itself) = “true”
Then this field can’t be unchecked anymore.
2.Use validation rule. Add following validation rule to that check box field.
If check_box_field = “False”
Show ScreenTip and Message: “Need to be checked”
With this validation rule, if check box has not selected, validation error will be displayed and stop prevent form submission. Let me know if you have any question.

Answer 3

I figure out this solution that worked as I expected but i cant display the error messages on the view.
[AttributeUsage(AttributeTargets.Class, AllowMultiple = true)]
public class AtLeastOnePropertyAttribute : ValidationAttribute
{
public AtLeastOnePropertyAttribute(string otherProperties)
{
if (otherProperties == null)
{
throw new ArgumentNullException("otherProperties");
}
OtherProperties = otherProperties;
}
public string OtherProperties { get; private set; }
public string OtherPropertyDisplayName { get; internal set; }
public override string FormatErrorMessage(string name)
{
return String.Format(CultureInfo.CurrentCulture, ErrorMessageString, name, OtherPropertyDisplayName ?? OtherProperties);
}
public override bool IsValid(object value)
{
var typeInfo = value.GetType();
var propertiesToGet = OtherProperties.Split(',');
var values = propertiesToGet.Select(propertyName => (bool) typeInfo.GetProperty(propertyName).GetValue(value)).ToList();
return values.Any(v => v);
}
public override object TypeId
{
get
{
return new object();
}
}
}
And in the DTO class:
[AtLeastOneProperty("T0 ,T1,T2", ErrorMessage = #"At least one field should be marked as true.")]
[AtLeastOneProperty("P0,P1", ErrorMessage = #"At least one field should be marked as true.")]
public class TestDTO
{
//Properties
}

Answer 4

Here is another way with FluentValidation.
RuleFor(x => x).Must(x =>
{
if (!x.checkbox1 &&
!x.checkbox2 &&
!x.checkbox3)
{
return false;
}
return true;
})
.WithMessage("Please select at least one checkbox.");
You could also run a foreach loop on a list of checkboxes and verify all boxes are not checked and throw the error.