ASP Net Core 3.1 Custom Validation Attribute Multiple

Question

I have a question about custom validator allowing multiple attribute I need to display a modal based on DOB. I'm having problems adding data-val properties in AddValidation method is only displaying the properties of the first attribute.

[AgeRange("ModalA", 0, 64, ErrorMessage = "Modal A Error")]
[AgeRange("ModalB", 65, 80, ErrorMessage = "Modal B Error")]
public override DateTime? DateOfBirth { get; set; }

[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field | AttributeTargets.Parameter, AllowMultiple = true, Inherited = false)]
public class AgeRangeAttribute : ValidationAttribute, IClientModelValidator
{
    public AgeValidationProperties ValidationProps { get; set; }
 
    public AgeRangeAttribute(string id, int yearMinimum, int yearMaximum)
    {
        //Init
        ValidationProps = new AgeValidationProperties()
        {
            YearMinimum = yearMinimum,
            YearMaximum = yearMaximum,
            Id = id
        };
 
    }
 
    protected override ValidationResult? IsValid(object? value, ValidationContext validationContext)
    {
        //Logic for Valid
    }
   
    public void AddValidation(ClientModelValidationContext context)
    {
//UPDATE!!!!
        var attributes = context.ModelMetadata.ContainerMetadata
                                            .ModelType.GetProperty(context.ModelMetadata.PropertyName)
                                            .GetCustomAttributes(typeof(AgeRangeAttribute), false)
                                            .Cast<AgeRangeAttribute>();

            var props = attributes.Select(x => x.ValidationProps).ToList();
            var messages = attributes.Select(x => x.ErrorMessage).ToList();

            MergeAttribute(context.Attributes, "data-val", "true");
            MergeAttribute(context.Attributes, "data-val-agerange", JsonConvert.SerializeObject(messages));

            MergeAttribute(context.Attributes, "data-val-agerange-props", JsonConvert.SerializeObject(props));
    }
}
 
public class AgeValidationProperties
{
  public int YearMinimum { get; set; }
  public int YearMaximum { get; set; }
  public string Id { get; set; }
}

I want to validate DOB property based on the rules added in the DataAnnotations decorator if age is lower than 64 years old in client will display ModalA and if age is between 65 and 80 will display ModalB and greater than 80 is a valid date.

HTML generated

Chen · Accepted Answer · 2022-12-02 04:11:32Z

1

You can return error message directly in AgeRangeAttribute.

I did a simple test, you can refer to it：

AgeRangeAttribute :

[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field | AttributeTargets.Parameter, AllowMultiple = true, Inherited = false)]
    public class AgeRangeAttribute : ValidationAttribute, IClientModelValidator
    {
        public AgeValidationProperties ValidationProps { get; set; }

        public int Year { get; }

        public AgeRangeAttribute(string id, int yearMinimum, int yearMaximum)
        {
            //Init
            ValidationProps = new AgeValidationProperties()
            {
                YearMinimum = yearMinimum,
                YearMaximum = yearMaximum,
                Id = id
            };

        }

        protected override ValidationResult? IsValid(object? value, ValidationContext validationContext)
        {
            if ((int)value < ValidationProps.YearMaximum) {
                return new ValidationResult(GetErrorMessage());
            }
            
            return ValidationResult.Success;
            //Logic for Valid
        }

        public void AddValidation(ClientModelValidationContext context)
        {
            MergeAttribute(context.Attributes, "data-val", "true");
            MergeAttribute(context.Attributes, "data-val-agerange", GetErrorMessage());

            var year = Year.ToString(CultureInfo.InvariantCulture);
            MergeAttribute(context.Attributes, "data-val-agerange-props",year);
        }

        public string GetErrorMessage() 
        {
            if (ValidationProps.Id == "ModalA")
            {
                return "Your age is not valid because is lower than 64 years old";
            }
            else 
            {
                return "Your age is not valid because is between 65 and 80 years old.";
            }
        }

        private static bool MergeAttribute(IDictionary<string, string> attributes, string key, string value)
        {
            if (attributes.ContainsKey(key))
            {
                return false;
            }

            attributes.Add(key, value);
            return true;
        }
    }
    public class AgeValidationProperties
    {
        public int YearMinimum { get; set; }
        public int YearMaximum { get; set; }
        public string Id { get; set; }
    }

Attributes that need to be validated:

[AgeRange("ModalA", 0, 64)]
[AgeRange("ModalB", 65, 80)]
public int Age { get; set; }

View:

<div class="row">
    <div class="col-md-4">
        <form method="post" asp-action="Index">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <div class="form-group">
                <label asp-for="@Model.Age" class="control-label"></label>
                <input asp-for="@Model.Age" class="form-control" />
                <span asp-validation-for="@Model.Age" class="text-danger"></span>
            </div>
            <div class="form-group">
                <input type="submit" value="Submit" class="btn btn-primary" />
            </div>
        </form>
    </div>
</div>

@section Scripts {
    @{
        await Html.RenderPartialAsync("_ValidationScriptsPartial");
    }
}

Result:

Hope this can help you.

answered Dec 2, 2022 at 4:11

Chen

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4 Comments

smashraid Over a year ago

Thanks Chen I tested but having an error because of Year property not able to find in the code where do you assigned. public int Year { get; }

Chen Over a year ago

Hi @smashraid, I'm not using the Year property in my test, so I don't pass it in. If you need to use it, you can pass it in and do whatever you want with it. If you don't need it, you can just remove it.

smashraid Over a year ago

I tested and is working as expected from server side the problem is client side data-val-agerange-props and data-val-agerange only display first data annotation [AgeRange("ModalA", 0, 64)] check this link ibb.co/MnNKtjM

smashraid Over a year ago

Thank you very much @chen I updated the post with the final answer related to client side.

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