aspnetcore/src/Microsoft.AspNet.Mvc.DataAnnotations/CompareAttributeAdapter.cs

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Globalization;
using Microsoft.Extensions.Localization;

namespace Microsoft.AspNet.Mvc.ModelBinding.Validation
{
    public class CompareAttributeAdapter : AttributeAdapterBase<CompareAttribute>
    {
        public CompareAttributeAdapter(CompareAttribute attribute, IStringLocalizer stringLocalizer)
            : base(new CompareAttributeWrapper(attribute), stringLocalizer)
        {
            if (attribute == null)
            {
                throw new ArgumentNullException(nameof(attribute));
            }
        }

        public override IEnumerable<ModelClientValidationRule> GetClientValidationRules(
            ClientModelValidationContext context)
        {
            if (context == null)
            {
                throw new ArgumentNullException(nameof(context));
            }

            var errorMessage = GetErrorMessage(context);
            var clientRule = new ModelClientValidationEqualToRule(errorMessage, "*." + Attribute.OtherProperty);
            return new[] { clientRule };
        }

        /// <inheritdoc />
        public override string GetErrorMessage(ModelValidationContextBase validationContext)
        {
            if (validationContext == null)
            {
                throw new ArgumentNullException(nameof(validationContext));
            }

            var displayName = validationContext.ModelMetadata.GetDisplayName();
            var otherPropertyDisplayName = CompareAttributeWrapper.GetOtherPropertyDisplayName(
                validationContext,
                Attribute);

            ((CompareAttributeWrapper)Attribute).ValidationContext = validationContext;

            return GetErrorMessage(validationContext.ModelMetadata, displayName, otherPropertyDisplayName);
        }

        // TODO: This entire class is needed because System.ComponentModel.DataAnnotations.CompareAttribute doesn't
        // populate OtherPropertyDisplayName until you call FormatErrorMessage.
        private sealed class CompareAttributeWrapper : CompareAttribute
        {
            public ModelValidationContextBase ValidationContext { get; set; }

            public CompareAttributeWrapper(CompareAttribute attribute)
                : base(attribute.OtherProperty)
            {
                // Copy settable properties from wrapped attribute. Don't reset default message accessor (set as
                // CompareAttribute constructor calls ValidationAttribute constructor) when all properties are null to
                // preserve default error message. Reset the message accessor when just ErrorMessageResourceType is
                // non-null to ensure correct InvalidOperationException.
                if (!string.IsNullOrEmpty(attribute.ErrorMessage) ||
                    !string.IsNullOrEmpty(attribute.ErrorMessageResourceName) ||
                    attribute.ErrorMessageResourceType != null)
                {
                    ErrorMessage = attribute.ErrorMessage;
                    ErrorMessageResourceName = attribute.ErrorMessageResourceName;
                    ErrorMessageResourceType = attribute.ErrorMessageResourceType;
                }
            }

            public override string FormatErrorMessage(string name)
            {
                var displayName = ValidationContext.ModelMetadata.GetDisplayName();
                return string.Format(CultureInfo.CurrentCulture,
                                     ErrorMessageString,
                                     displayName,
                                     GetOtherPropertyDisplayName(ValidationContext, this));
            }

            public static string GetOtherPropertyDisplayName(
                ModelValidationContextBase validationContext,
                CompareAttribute attribute)
            {
                // The System.ComponentModel.DataAnnotations.CompareAttribute doesn't populate the
                // OtherPropertyDisplayName until after IsValid() is called. Therefore, at the time we get
                // the error message for client validation, the display name is not populated and won't be used.
                var otherPropertyDisplayName = attribute.OtherPropertyDisplayName;
                if (otherPropertyDisplayName == null && validationContext.ModelMetadata.ContainerType != null)
                {
                    var otherProperty = validationContext.MetadataProvider.GetMetadataForProperty(
                        validationContext.ModelMetadata.ContainerType,
                        attribute.OtherProperty);
                    if (otherProperty != null)
                    {
                        return otherProperty.GetDisplayName();
                    }
                }

                return attribute.OtherProperty;
            }
        }
    }
}