Conditional Validation

Often, certain fields are only requiredor only subject to range constraintsif other fields contain specific values. Instead of writing complex IValidatableObject methods, Sannr natively handles conditional rule application entirely via Source Generation.

RequiredIf

RequiredIf allows you to make a property dependent on the state of a sibling property. This condition evaluates quickly via AOT static lookups.

public class UserProfile
{
    public string Country { get; set; }

    // ZipCode is only mandatory when Country == "USA"
    [RequiredIf(nameof(Country), "USA")]
    public string ZipCode { get; set; }
    
    public bool IsCompany { get; set; }
    
    // Tax ID is only required if the user registers as a company entity
    [RequiredIf(nameof(IsCompany), true)]
    public string TaxId { get; set; }
}

Conditional Range

Numeric boundaries can shift based on enum or string states elsewhere in the model.

public class LoanApplication
{
    [Required]
    public string LoanType { get; set; } // "personal", "business", "mortgage"

    [ConditionalRange("LoanType", "personal", 1000, 50000)]
    [ConditionalRange("LoanType", "business", 5000, 1000000)]
    [ConditionalRange("LoanType", "mortgage", 50000, 5000000)]
    public decimal Amount { get; set; }
}

Client-Side Rule Generation

Because these conditions are strongly statically typed, Sannr will emit the equivalent RequiredIf Javascript/TypeScript configuration bounds without manual duplication.