Supported Attributes Reference

Sannr provides a robust set of validation attributes designed for Native AOT scenarios. While many mirror the standard System.ComponentModel.DataAnnotations, Sannr includes additional "Power Attributes" for conditional logic and data sanitization.

All attributes are located in the Sannr namespace.

Table of Contents

• Standard Validation
  • Required
  • StringLength
  • Range
• Format & Patterns
  • EmailAddress
  • CreditCard
  • Url
  • Phone
  • FileExtensions
  • FutureDate
• Advanced Logic
  • RequiredIf
  • AllowedValues
  • ConditionalRange
  • CustomValidator
• Data Sanitization
  • Sanitize
• Metadata
  • Display

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Standard Validation

[Required]

Specifies that a data field is required.

Behavior:

• Checks if the value is null.
• If the value is a string, it also checks if it is empty or consists only of whitespace.

Parameter	Type	Description
ErrorMessage	string	Custom error message.
Group	string	validation group (context) this rule applies to.
Severity	Severity	Error (Default), Warning, or Info.

Example:

[Required(ErrorMessage = "Username is mandatory.")]
public string Username { get; set; }

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[StringLength]

Specifies the minimum and maximum length of characters that are allowed in a data field.

Parameter	Type	Description
MaximumLength	int	(Constructor) The maximum allowed length.
MinimumLength	int	The minimum required length (Optional).

Example:

[StringLength(50, MinimumLength = 3, ErrorMessage = "Must be between 3 and 50 chars.")]
public string DisplayName { get; set; }

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[Range]

Specifies the numeric range constraints for the value of a data field.

Parameter	Type	Description
Minimum	double | int	(Constructor) The minimum allowed value.
Maximum	double | int	(Constructor) The maximum allowed value.

Example:

[Range(18, 120, ErrorMessage = "Age must be valid.")]
public int Age { get; set; }

[Range(0.01, 1000.00)]
public double Price { get; set; }

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Format & Patterns

[EmailAddress]

Validates that the property matches a valid email address format.

Performance Note: Sannr uses a pre-compiled, source-generated Regex for maximum throughput.

Example:

[EmailAddress]
public string ContactEmail { get; set; }

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[CreditCard]

Validates that the property contains a valid credit card number structure (13-19 digits, allowing dashes/spaces).

Example:

[CreditCard]
public string PaymentCard { get; set; }

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[Url]

Validates that the property is a well-formed URL (starting with http:// or https://).

Example:

[Url]
public string PortfolioUrl { get; set; }

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[Phone]

Validates that the property contains valid phone characters (digits, spaces, dashes, parentheses, +).

Example:

[Phone]
public string PhoneNumber { get; set; }

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[FileExtensions]

Validates that a string (representing a file name) ends with one of the specified extensions.

Parameter	Type	Description
Extensions	string	Comma-separated list of extensions (default: "png,jpg,jpeg,gif").

Example:

[FileExtensions(Extensions = "pdf,docx,txt")]
public string ResumeFileName { get; set; }

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[FutureDate]

Validates that the property (DateTime or DateTimeOffset) is in the future.

Example:

[FutureDate]
public DateTime DeliveryDate { get; set; }

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Advanced Logic

[RequiredIf]

Marks a property as required only if another property has a specific value.

Parameter	Type	Description
OtherProperty	string	(Constructor) Name of the property to check against.
TargetValue	object	(Constructor) The value that triggers the requirement.

Example:

public string Country { get; set; }

// State is strictly required only when Country is "USA"
[RequiredIf(nameof(Country), "USA")]
public string State { get; set; }

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[AllowedValues]

Restricts a property to a predefined set of values.

Parameter	Type	Description
Values	string[]	(Constructor) Array of allowed string values.

Example:

[AllowedValues("active", "inactive", "pending")]
public string Status { get; set; }

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[ConditionalRange]

Applies numeric range validation only when another property matches a specific value.

Parameter	Type	Description
OtherProperty	string	(Constructor) Name of the property to check against.
TargetValue	object	(Constructor) The value that triggers the range check.
Minimum	double	(Constructor) The minimum allowed value.
Maximum	double	(Constructor) The maximum allowed value.

Example:

public string Currency { get; set; }

[ConditionalRange("Currency", "USD", 1, 1000)]
public decimal Amount { get; set; }

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[CustomValidator]

Delegates validation to a custom static method. This is the primary way to implement complex business logic or database checks.

Parameter	Type	Description
ValidatorType	Type	(Constructor) The class containing the static method.
MethodName	string	The name of the method (Default: "Check").
IsAsync	bool	Set to true if the method returns Task<ValidationResult>.

Method Signature Requirements:

• Sync: public static ValidationResult Check(T value, IServiceProvider sp)
• Async: public static Task<ValidationResult> Check(T value, IServiceProvider sp)

Example:

[CustomValidator(typeof(UserRules), nameof(UserRules.IsUniqueAsync), IsAsync = true)]
public string Username { get; set; }

public static class UserRules
{
    public static async Task<ValidationResult> IsUniqueAsync(string username, IServiceProvider sp)
    {
        // ... database check logic ...
        return ValidationResult.Success();
    }
}

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Data Sanitization

[Sanitize]

Automatically modifies the input data before validation rules are executed. This is useful for normalizing data (e.g., standardizing casing or removing accidental whitespace).

Parameter	Type	Description
Trim	bool	If true, executes .Trim() on the string.
ToUpper	bool	If true, converts string to Uppercase.
ToLower	bool	If true, converts string to Lowercase.

Example:

// Input: "  john.doe  "
// Result: "JOHN.DOE"
[Sanitize(Trim = true, ToUpper = true)]
public string UserId { get; set; }

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Metadata

[Display]

Provides a user-friendly name for the property, which is used in formatted error messages.

Parameter	Type	Description
Name	string	The friendly display name.

Example:

[Display(Name = "User's Age")]
[Range(18, 99)]
public int Age { get; set; }
// Error: "The field User's Age must be between 18 and 99."