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using System.ComponentModel.DataAnnotations.Resources;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
namespace System.ComponentModel.DataAnnotations {
/// <summary>
/// Validation attribute to assert a string property, field or parameter does not exceed a maximum length
/// </summary>
[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field | AttributeTargets.Parameter, AllowMultiple = false)]
[SuppressMessage("Microsoft.Performance", "CA1813:AvoidUnsealedAttributes", Justification = "We want users to be able to extend this class")]
public class StringLengthAttribute : ValidationAttribute {
/// <summary>
/// Gets the maximum acceptable length of the string
/// </summary>
public int MaximumLength {
get;
private set;
}
/// <summary>
/// Gets or sets the minimum acceptable length of the string
/// </summary>
public int MinimumLength {
get;
set;
}
/// <summary>
/// Constructor that accepts the maximum length of the string.
/// </summary>
/// <param name="maximumLength">The maximum length, inclusive. It may not be negative.</param>
public StringLengthAttribute(int maximumLength)
: base(() => DataAnnotationsResources.StringLengthAttribute_ValidationError) {
this.MaximumLength = maximumLength;
}
/// <summary>
/// Override of <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 value to test.</param>
/// <returns><c>true</c> if the value is null or less than or equal to the set maximum length</returns>
/// <exception cref="InvalidOperationException"> is thrown if the current attribute is ill-formed.</exception>
#if !SILVERLIGHT
public
#else
internal
#endif
override bool IsValid(object value) {
// Check the lengths for legality
this.EnsureLegalLengths();
// Automatically pass if value is null. RequiredAttribute should be used to assert a value is not null.
// We expect a cast exception if a non-string was passed in.
int length = value == null ? 0 : ((string)value).Length;
return value == null || (length >= this.MinimumLength && length <= this.MaximumLength);
}
/// <summary>
/// Override of <see cref="ValidationAttribute.FormatErrorMessage"/>
/// </summary>
/// <param name="name">The name to include in the formatted string</param>
/// <returns>A localized string to describe the maximum acceptable length</returns>
/// <exception cref="InvalidOperationException"> is thrown if the current attribute is ill-formed.</exception>
public override string FormatErrorMessage(string name) {
this.EnsureLegalLengths();
bool useErrorMessageWithMinimum = this.MinimumLength != 0 && !this.CustomErrorMessageSet;
string errorMessage = useErrorMessageWithMinimum ?
DataAnnotationsResources.StringLengthAttribute_ValidationErrorIncludingMinimum : this.ErrorMessageString;
// it's ok to pass in the minLength even for the error message without a {2} param since String.Format will just
// ignore extra arguments
return String.Format(CultureInfo.CurrentCulture, errorMessage, name, this.MaximumLength, this.MinimumLength);
}
/// <summary>
/// Checks that MinimumLength and MaximumLength have legal values. Throws InvalidOperationException if not.
/// </summary>
private void EnsureLegalLengths() {
if (this.MaximumLength < 0) {
throw new InvalidOperationException(DataAnnotationsResources.StringLengthAttribute_InvalidMaxLength);
}
if (this.MaximumLength < this.MinimumLength) {
throw new InvalidOperationException(String.Format(CultureInfo.CurrentCulture, DataAnnotationsResources.RangeAttribute_MinGreaterThanMax, this.MaximumLength, this.MinimumLength));
}
}
}
}
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