Blazor ValidationMessage being conditional

Question

Hello,

I have a registration form where the users can select if they are private or company.

What I need is to make the Company Name validation conditional. Meaning, if they select a company it gets enabled and if they select a private it gets disabled.

public class Credential : ValidationAttribute 
{
    [Required(ErrorMessageResourceName = "Validation_RequiredField", ErrorMessageResourceType = typeof(Resources))]
    public int? AccountType { get; set; }
    [Required(ErrorMessageResourceName = "Validation_RequiredField", ErrorMessageResourceType = typeof(Resources))]
    public string? FirstName { get; set; }
    [Required(ErrorMessageResourceName = "Validation_RequiredField", ErrorMessageResourceType = typeof(Resources))]
    public string? LastName { get; set; }
    [Required(ErrorMessageResourceName = "Validation_RequiredField", ErrorMessageResourceType = typeof(Resources))]
    public string? CompanyName { get; set; }

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        var cred = (Credential)validationContext.ObjectInstance;
        if(cred.AccountType == 0)
        {
            //-- Disable CompanyName validation;
        }
        else
       {
           //-- Enable CompanyName validation;
       }
        return ValidationResult.Success;
    }
}


    
        
            @foreach (var accounttype in accounttypes)
            {
                @if (accounttypes.IndexOf(accounttype) == 0)
                {
                    
                    @accounttype 
                }
                else
                {
                    
                    @accounttype 
                }
            }
        
    



    
        
            
             First name
            
        
    
    
        
            
             Last name
            
        
    



    
        
            
             Company name

Thank you so much!

Answer

You will need to write custom validation, or pick a 3rd party validation library that supports conditional validation.

https://zcusa.951200.xyz/en-us/aspnet/core/blazor/forms/validation?view=aspnetcore-9.0

Answer

Hi @Kuler Master

For conditional validation you could refer to the demo below:

Model design and custom ValidationAttribute

public class Credential
{
    [Required]
    public int AccountType { get; set; } 
    [Required]
    public string? FirstName { get; set; }
    [Required]
    public string LastName { get; set; }
    [RequieredIf(Condition = "AccountType")]
    public string CompanyName { get; set; }  // Make CompanyName not required initially.
}
public class RequieredIfAttribute : ValidationAttribute
{
    public string? Condition { get; set; }
    public RequieredIfAttribute()
    {
    }
    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        string data = (string)value;
        int? selectedType = (int?)validationContext.ObjectType.GetProperty(Condition).GetValue(validationContext.ObjectInstance, null);
        if (string.IsNullOrEmpty(data) && selectedType != 0)
        {
            return new ValidationResult("Company Name is requiered.");
        }
        return ValidationResult.Success;
    }
}

Razor Component

@page "/"
@rendermode InteractiveServer

    
    
    
        
            
                
                    @foreach (var accounttype in accounttypes)
                    {
                        var index = accounttypes.IndexOf(accounttype);
                        
                        @accounttype
                        

                    }
                
              
            
        
    
    
        
            
                
                 First name
                
            
        
        
            
                
                 Last name
                
            
        
    
    
        
            
                
                 Company name
                
            
        
    
    

@code {
    private EditContext? editContext;
    private List accounttypes = new List { "Private", "Company" };
    private Credential _credential { get; set; } = new();
    private void Submit(){
        
    }
}

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Rena

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Blazor ValidationMessage being conditional

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