String Validation

String Validation

ZodString (namespace ZodSharp.Schemas) validates string values. ParseInternal rejects null with an invalid_type error ("Expected string, but got null"); on success the accumulated rules run.

using ZodSharp;

var schema = Z.String().Min(3).Max(50).Email();
var result = schema.Validate("[email protected]");

Methods

Method	Signature	Rule added
Min	Min(int minLength)	MinLengthRule — too_small via validation_failed when too short
Max	Max(int maxLength)	MaxLengthRule
Length	Length(int length)	exact length (both bounds)
Email	Email()	EmailRule — static compiled regex
Regex	Regex(Regex pattern, string? message) / Regex(string pattern, string? message)	RegexRule; the string overload compiles with a 100 ms timeout
Url	Url(string? message)	UrlRule — regex or absolute http/https URI
Phone	Phone(string? message)	PhoneRule — digits plus () .+-, at least one digit
CreditCard	CreditCard(string? message)	CreditCardRule — Luhn algorithm
Base64String	Base64String(string? message)	Base64StringRule — Convert.FromBase64String
UUID	UUID(string? message)	UUIDRule — char-scan, RFC 9562 versions 1-8, variant nibble 8-9/a-b, plus nil and max
UUID	UUID(UuidVersion version, string? message)	UUIDRule — requires a specific version (e.g. V7), variant nibble 8-9/a-b, nil/max rejected
StartsWith	StartsWith(string prefix, string? message)	StartsWithRule — ordinal comparison
EndsWith	EndsWith(string suffix, string? message)	EndsWithRule — ordinal comparison
ToLower	ToLower()	wraps a transform (ToLowerInvariant), returns a ZodString
ToUpper	ToUpper()	wraps a transform (ToUpperInvariant)
Trim	Trim()	wraps a transform (Trim)
ValidateSpan	ValidateSpan(ReadOnlySpan<char> value)	zero-allocation span validation

Note

ToLower, ToUpper, and Trim produce a new string on every validation — these are the only string validations that allocate on a successful path.

Examples

var email = Z.String().Email().Validate("[email protected]");

var url = Z.String().Url().Validate("https://example.com");

var uuid = Z.String().UUID().Validate("550e8400-e29b-41d4-a716-446655440000");

var uuidV7 = Z.String().UUID(UuidVersion.V7).Validate("0192b4c1-7a9b-7f5e-9a3c-2d4e6f8a0b1c");

var prefix = Z.String().StartsWith("https://");
var suffix = Z.String().EndsWith(".com");

var exact = Z.String().Length(10);

var normalized = Z.String().Trim().ToUpper().Validate("  hello  "); // "HELLO"

ReadOnlySpan<char> span = "[email protected]".AsSpan();
var spanResult = Z.String().Min(3).Max(50).Email().ValidateSpan(span);

Error messages

Rules produce ValidationError entries with code validation_failed and an empty path. Many methods accept a custom message parameter. Rule structs live in ZodSharp.Rules and can be reused standalone with IValidationRule<T>.

Span validation

ValidateSpan(ReadOnlySpan<char> value) avoids string allocations on the validation path. An empty span validates successfully as "".