Data Annotation conditional required attribute

Justin Davis

created 8 years ago

I'm wondering if the DataLayoutControl supports or has a way to toggle required fields.

Say I have a data model as such

C#
public enum CustomerType  
{  
    User,  
    Reseller  
}  

public class DataModel  
{  
    public string FirstName { get; set; }  
    public string LastName { get; set; }  

    public CustomerType CustomerType { get; set; } = CustomerType.User;  

    [Required(ErrorMessage = "Reseller name can not be null or empty.")] // need this to be conditional based on CustomerType.  
    public string ResellerName { get; set; }  
}

If i can set this required field manually that will work as well.

Please let me know.

Answers approved by DevExpress Support

DevExpress Support Team

created 8 years ago (modified 8 years ago)

Hi,

It is possible to accomplish this task by creating a custom RequiredAttribute. Override the RequiresValidationContext property to return true. In addition, override the IsValid method to return ValidationResult.Success if the CustomerType property value is User.

C#
[CustomRequiredAttribute(ErrorMessage = "Reseller name can not be null or empty.")]  
public string ResellerName { get; set; }

C#
public class CustomRequiredAttribute : RequiredAttribute {  
    public CustomRequiredAttribute() { }  
    public CustomerType ConditionParameter { get; set; }  
    protected override ValidationResult IsValid(object value, ValidationContext validationContext) {  
        DataModel model = validationContext.ObjectInstance as DataModel;  
        if (model != null && model.CustomerType == CustomerType.User)  
            return ValidationResult.Success;  
        return base.IsValid(value, validationContext);  
    }  
    public override bool RequiresValidationContext {  
        get {  
            return true;  
        }  
    }  
}

I should note that this approach will operate properly in .Net Framework 4.5 and higher since in the earlier .Net Framework versions, the RequiredAttribute class does not have the public virtual RequiresValidationContext property.

Please try the approach and let me know your results.

Comments (2)

Justin Davis 8 years ago

I had originally tried this with out
RequiresValidationContext = trueAfter setting this and refreshing the databindings this works as expected. Thank you. I have another question i'll go ahead and make a new topic for sense I can't seem to find it.

Thank you.

DevExpress Support Team 8 years ago

Thank you for informing us that the issue has been resolved. Please do not hesitate to contact us in case of any difficulty. We will be happy to help you!

Data Annotation conditional required attribute

Answers approved by DevExpress Support

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