50 lines
1.3 KiB
C#
50 lines
1.3 KiB
C#
using System;
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using System.ComponentModel.DataAnnotations;
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using System.Windows.Markup;
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using System.Xml;
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namespace example_csharp_app.Filters;
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[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field | AttributeTargets.Parameter, AllowMultiple = false)]
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public class XmlAttribute : ValidationAttribute
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{
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public XmlAttribute(): base("Passed string is not XML")
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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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/// <param name="value">The value to test</param>
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/// <returns>
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/// Returns <see langword="false" /> if the <paramref name="value" /> is null or an empty string.
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/// If <see cref="AllowEmptyStrings" /> then <see langword="true" /> is returned for empty strings.
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/// </returns>
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public override bool IsValid(object? value)
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{
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if (value is null || value is not string)
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{
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return false;
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}
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string possiblyXml = ((string)value).Trim();
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if (!possiblyXml.StartsWith('<') && !possiblyXml.EndsWith('>'))
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{
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return false;
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}
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XmlDocument xml = new XmlDocument();
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try
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{
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xml.LoadXml(possiblyXml);
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}
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catch (XmlException e)
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{
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// logme?
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return false;
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}
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return true;
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}
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}
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