Validation Attributes

Attribute Reference

Attribute	Applies to	Description
[ZValidate]	class / record / struct	Marks the type for code generation (must be partial)
[ZRequired]	property	Not null; for strings also not empty/whitespace
[ZMinLength(n)]	property (string / collection)	Minimum length or item count
[ZMaxLength(n)]	property (string / collection)	Maximum length or item count
[ZRange(min, max)]	property (numeric)	Inclusive numeric range
[ZEmail]	property (string)	Must match email regex
[ZUrl]	property (string)	Must be a valid absolute URI
[ZMatch(pattern)]	property (string)	Must match the given regex pattern
[ZNotEmpty]	property (collection / string)	Collection must have items; string must not be whitespace
[ZIn("a","b","c")]	property	Value must be one of the allowed values
[ZNotIn("x","y")]	property	Value must NOT be any of the specified values
[ZCreditCard]	property (string)	Must pass the Luhn algorithm check
[ZPhone]	property (string)	Must match phone number format
[ZCascade]	property	Stop after first rule failure for this property

Custom Error Messages

All attributes accept a Message property for custom error text:

[ZRequired(Message = "Please provide your name")]
[ZRange(1, 100, Message = "{PropertyName} must be 1-100, got {PropertyValue}")]
[ZMatch(@"^\d{3}-\d{4}$", Message = "Phone must be in format XXX-XXXX")]

Message Placeholders

Placeholder	Replaced with
{PropertyName}	The property name (e.g. “Email”)
{PropertyValue}	The actual value at runtime

CascadeMode — [ZCascade]

By default, all rules for a property are evaluated and all errors are reported. Add [ZCascade] to stop after the first failure:

[ZValidate]
public partial class LoginRequest
{
    [ZRequired] [ZMinLength(3)] [ZMaxLength(50)] [ZCascade]
    public string Username { get; set; } = "";
}

If Username is empty → only "Username is required." is reported. MinLength and MaxLength are skipped.

Without [ZCascade] → all three errors would be reported.

[ZIn] and [ZNotIn]

[ZValidate]
public partial class StatusUpdate
{
    [ZIn("draft", "active", "archived")]
    public string Status { get; set; } = "";

    [ZNotIn("admin", "root", "system")]
    public string Username { get; set; } = "";
}

[ZCreditCard] — Luhn Algorithm

[ZValidate]
public partial class PaymentForm
{
    [ZRequired] [ZCreditCard]
    public string CardNumber { get; set; } = "";
}

// Valid: "4111111111111111" (Visa test number)
// Invalid: "1234567890123456"

[ZPhone]

[ZPhone]
public string? PhoneNumber { get; set; }

// Valid: "+1-555-123-4567", "(555) 123 4567", "+48501234567"
// Invalid: "abc", "12"