/
MinLengthAttribute.cs
94 lines (85 loc) · 3.88 KB
/
MinLengthAttribute.cs
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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
namespace System.ComponentModel.DataAnnotations
{
/// <summary>
/// Specifies the minimum length of collection/string data allowed in a property.
/// </summary>
[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field | AttributeTargets.Parameter,
AllowMultiple = false)]
public class MinLengthAttribute : ValidationAttribute
{
/// <summary>
/// Initializes a new instance of the <see cref="MinLengthAttribute" /> class.
/// </summary>
/// <param name="length">
/// The minimum allowable length of collection/string data.
/// Value must be greater than or equal to zero.
/// </param>
[RequiresUnreferencedCode(CountPropertyHelper.RequiresUnreferencedCodeMessage)]
public MinLengthAttribute(int length)
: base(SR.MinLengthAttribute_ValidationError)
{
Length = length;
}
/// <summary>
/// Gets the minimum allowable length of the collection/string data.
/// </summary>
public int Length { get; }
/// <summary>
/// Determines whether a specified object is valid. (Overrides <see cref="ValidationAttribute.IsValid(object)" />)
/// </summary>
/// <remarks>
/// This method returns <c>true</c> if the <paramref name="value" /> is null.
/// It is assumed the <see cref="RequiredAttribute" /> is used if the value may not be null.
/// </remarks>
/// <param name="value">The object to validate.</param>
/// <returns>
/// <c>true</c> if the value is null or greater than or equal to the specified minimum length, otherwise
/// <c>false</c>
/// </returns>
/// <exception cref="InvalidOperationException">Length is less than zero.</exception>
[UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode", Justification = "The ctor is marked with RequiresUnreferencedCode.")]
public override bool IsValid(object? value)
{
// Check the lengths for legality
EnsureLegalLengths();
int length;
// Automatically pass if value is null. RequiredAttribute should be used to assert a value is not null.
if (value == null)
{
return true;
}
if (value is string str)
{
length = str.Length;
}
else if (!CountPropertyHelper.TryGetCount(value, out length))
{
throw new InvalidCastException(SR.Format(SR.LengthAttribute_InvalidValueType, value.GetType()));
}
return length >= Length;
}
/// <summary>
/// Applies formatting to a specified error message. (Overrides <see cref="ValidationAttribute.FormatErrorMessage" />)
/// </summary>
/// <param name="name">The name to include in the formatted string.</param>
/// <returns>A localized string to describe the minimum acceptable length.</returns>
public override string FormatErrorMessage(string name) =>
// An error occurred, so we know the value is less than the minimum
string.Format(CultureInfo.CurrentCulture, ErrorMessageString, name, Length);
/// <summary>
/// Checks that Length has a legal value.
/// </summary>
/// <exception cref="InvalidOperationException">Length is less than zero.</exception>
private void EnsureLegalLengths()
{
if (Length < 0)
{
throw new InvalidOperationException(SR.MinLengthAttribute_InvalidMinLength);
}
}
}
}