52 lines
1.7 KiB
C#
52 lines
1.7 KiB
C#
namespace System.ComponentModel.DataAnnotations {
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using System;
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using System.Collections.Generic;
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using System.ComponentModel.DataAnnotations;
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using System.ComponentModel.DataAnnotations.Resources;
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using System.Linq;
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[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field | AttributeTargets.Parameter, AllowMultiple = false)]
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public sealed class CreditCardAttribute : DataTypeAttribute {
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public CreditCardAttribute()
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: base(DataType.CreditCard) {
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// DevDiv 468241: set DefaultErrorMessage not ErrorMessage, allowing user to set
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// ErrorMessageResourceType and ErrorMessageResourceName to use localized messages.
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DefaultErrorMessage = DataAnnotationsResources.CreditCardAttribute_Invalid;
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}
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public override bool IsValid(object value) {
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if (value == null) {
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return true;
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}
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string ccValue = value as string;
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if (ccValue == null) {
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return false;
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}
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ccValue = ccValue.Replace("-", "");
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ccValue = ccValue.Replace(" ", "");
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int checksum = 0;
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bool evenDigit = false;
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// http://www.beachnet.com/~hstiles/cardtype.html
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foreach (char digit in ccValue.Reverse()) {
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if (digit < '0' || digit > '9') {
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return false;
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}
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int digitValue = (digit - '0') * (evenDigit ? 2 : 1);
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evenDigit = !evenDigit;
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while (digitValue > 0) {
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checksum += digitValue % 10;
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digitValue /= 10;
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}
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}
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return (checksum % 10) == 0;
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}
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}
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}
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