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