inotifydataerrorinfo.snippet

<?xml version="1.0" encoding="utf-8"?>
<CodeSnippets xmlns="http://schemas.microsoft.com/VisualStudio/2010/CodeSnippet">
  <CodeSnippet Format="1.0.0">
    <Header>
      <Title>INotifyDataErrorInfo の実装</Title>
      <Description>INotifyDataErrorInfo を実装します。</Description>
      <SnippetTypes>
        <SnippetType>Expansion</SnippetType>
      </SnippetTypes>
      <Shortcut>inotifydataerrorinfo</Shortcut>
    </Header>
    <Snippet>
      <Code Language="csharp" Kind="method decl">
        <![CDATA[/// <summary>
        /// エンティティ全体の検証エラーです。
        /// </summary>
        private readonly IDictionary<string, IList<string>> _errors = new Dictionary<string, IList<string>>();

        /// <inheritdoc />
        public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged;

        /// <inheritdoc />
        public bool HasErrors
        {
            get { return _errors.Count != 0; }
        }

        /// <inheritdoc />
        public IEnumerable GetErrors(string propertyName)
        {
            if (string.IsNullOrEmpty(propertyName))
            {
                return _errors.Values.SelectMany(x => x);
            }

            IList<string> errorMessages;
            return _errors.TryGetValue(propertyName, out errorMessages) ? errorMessages : null;
        }

        /// <summary>
        /// <see cref="ErrorsChanged"/>イベントを発生させます。
        /// </summary>
        /// <param name="propertyName">エラーのあるプロパティ名</param>
        protected virtual void OnErrorsChanged(string propertyName)
        {
            var handler = ErrorsChanged;
            if (handler != null)
            {
                handler(this, new DataErrorsChangedEventArgs(propertyName));
            }
        }

        /// <summary>
        /// 指定のプロパティを検証します。
        /// </summary>
        /// <param name="propertyName">検証するプロパティ名</param>
        /// <param name="value">検証するプロパティの値</param>
        private void ValidateProperty(string propertyName, object value)
        {
            var validationResults = new List<ValidationResult>();
            if (Validator.TryValidateProperty(value, new ValidationContext(this) { MemberName = propertyName }, validationResults))
            {
                if (_errors.Remove(propertyName))
                {
                    OnErrorsChanged(propertyName);
                }
            }
            else
            {
                _errors[propertyName] = validationResults.Select(x => x.ErrorMessage).ToList();
                OnErrorsChanged(propertyName);
            }
        }]]>
      </Code>
    </Snippet>
  </CodeSnippet>
</CodeSnippets>