我是使用mvvm进行wpf应用开发的新手。所以如果我要问开箱即可，请忽略。我有一个模型类，我使用数据注释验证数据。
以下是模型类的代码部分
/// <summary>
/// The firstname of the person.
/// </summary>
[Required(AllowEmptyStrings = false, ErrorMessage = "First name must not be empty.")]
[MaxLength(20, ErrorMessage = "Maximum of 20 characters is allowed.")]
public string Firstname { get; set; }
/// <summary>
/// The lastname of the person.
/// </summary>
[Required(AllowEmptyStrings = false, ErrorMessage = "Address must not be empt.")]
public string Address { get; set; }
[MaxLength(20, ErrorMessage = "Maximum of 20 characters is allowed.")]
public string PhoneNum { get; set; }
我的验证对xaml完全没有问题，工作正常并且在＆＃34;必需和最大长度属性＆＃34;的情况下在文本框中显示错误。现在我想在模型类中使用正则表达式属性和我的电话号码。喜欢
[RegularExpression("^[0-9]*$", ErrorMessage = "Phone Num must be numeric")]
[MaxLength(20, ErrorMessage = "Maximum of 20 characters is allowed.")]
public string PhoneNum { get; set; }
以下是我的BaseModel类中IDataErrorInfo的代码。
using Annotations;
/// <summary>
/// Abstract base class for all models.
/// </summary>
public abstract class BaseModel : INotifyPropertyChanged, IDataErrorInfo
{
#region constants
private static List<PropertyInfo> _propertyInfos;
#endregion
#region events
/// <summary>
/// Occurs when a property value changes.
/// </summary>
public event PropertyChangedEventHandler PropertyChanged;
#endregion
#region constructors and destructors
/// <summary>
/// Default constructor.
/// </summary>
public BaseModel()
{
InitCommands();
}
#endregion
#region explicit interfaces
/// <summary>
/// Gets an error message indicating what is wrong with this object.
/// </summary>
/// <returns>
/// An error message indicating what is wrong with this object. The default is an empty string ("").
/// </returns>
public string Error => string.Empty;
/// <summary>
/// Gets the error message for the property with the given name.
/// </summary>
/// <returns>
/// The error message for the property. The default is an empty string ("").
/// </returns>
/// <param name="columnName">The name of the property whose error message to get. </param>
public string this[string columnName]
{
get
{
CollectErrors();
return Errors.ContainsKey(columnName) ? Errors[columnName] : string.Empty;
}
}
#endregion
#region methods
/// <summary>
/// Override this method in derived types to initialize command logic.
/// </summary>
protected virtual void InitCommands()
{
}
/// <summary>
/// Can be overridden by derived types to react on the finisihing of error-collections.
/// </summary>
protected virtual void OnErrorsCollected()
{
}
/// <summary>
/// Raises the <see cref="PropertyChanged" /> event.
/// </summary>
/// <param name="propertyName">The name of the property which value has changed.</param>
[NotifyPropertyChangedInvocator]
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
/// <summary>
/// Is called by the indexer to collect all errors and not only the one for a special field.
/// </summary>
/// <remarks>
/// Because <see cref="HasErrors" /> depends on the <see cref="Errors" /> dictionary this
/// ensures that controls like buttons can switch their state accordingly.
/// </remarks>
private void CollectErrors()
{
Errors.Clear();
PropertyInfos.ForEach(
prop =>
{
var currentValue = prop.GetValue(this);
var requiredAttr = prop.GetCustomAttribute<RequiredAttribute>();
var maxLenAttr = prop.GetCustomAttribute<MaxLengthAttribute>();
if (requiredAttr != null)
{
if (string.IsNullOrEmpty(currentValue?.ToString() ?? string.Empty))
{
Errors.Add(prop.Name, requiredAttr.ErrorMessage);
}
}
if (maxLenAttr != null)
{
if ((currentValue?.ToString() ?? string.Empty).Length > maxLenAttr.Length)
{
Errors.Add(prop.Name, maxLenAttr.ErrorMessage);
}
}
// further attributes
});
// we have to this because the Dictionary does not implement INotifyPropertyChanged
OnPropertyChanged(nameof(HasErrors));
OnPropertyChanged(nameof(IsOk));
// commands do not recognize property changes automatically
OnErrorsCollected();
}
#endregion
#region properties
/// <summary>
/// Indicates whether this instance has any errors.
/// </summary>
public bool HasErrors => Errors.Any();
/// <summary>
/// The opposite of <see cref="HasErrors" />.
/// </summary>
/// <remarks>
/// Exists for convenient binding only.
/// </remarks>
public bool IsOk => !HasErrors;
/// <summary>
/// Retrieves a list of all properties with attributes required for <see cref="IDataErrorInfo" /> automation.
/// </summary>
protected List<PropertyInfo> PropertyInfos
{
get
{
return _propertyInfos
?? (_propertyInfos =
GetType()
.GetProperties(BindingFlags.Public | BindingFlags.Instance)
.Where(prop => prop.IsDefined(typeof(RequiredAttribute), true) || prop.IsDefined(typeof(MaxLengthAttribute), true))
.ToList());
}
}
/// <summary>
/// A dictionary of current errors with the name of the error-field as the key and the error
/// text as the value.
/// </summary>
private Dictionary<string, string> Errors { get; } = new Dictionary<string, string>();
#endregion
}
}
如何在Basemodel类中添加正则表达式属性？任何帮助将不胜感激。感谢
答案 0 :(得分：1)
您可以获取从ValidationAttribute派生的所有属性，而不是向您的媒体添加更多或条款 - || 。所有DataAnnotation属性都派生自此类：
/// <summary>
/// Retrieves a list of all properties with attributes required for <see cref="IDataErrorInfo" /> automation.
/// </summary>
protected List<PropertyInfo> PropertyInfos
{
get
{
return _propertyInfos
?? (_propertyInfos =
GetType()
.GetProperties(BindingFlags.Public | BindingFlags.Instance)
.Where(prop => prop.IsDefined(typeof(ValidationAttribute), true))
.ToList());
}
}
如果你不喜欢这种方法，你可以添加一个||您要处理的每种属性类型的子句：
protected List<PropertyInfo> PropertyInfos
{
get
{
return _propertyInfos
?? (_propertyInfos =
GetType()
.GetProperties(BindingFlags.Public | BindingFlags.Instance)
.Where(prop =>
prop.IsDefined(typeof(RequiredAttribute), true) ||
prop.IsDefined(typeof(MaxLengthAttribute), true) ||
prop.IsDefined(typeof(RegularExpressionAttribute), true) )
.ToList());
}
}
根据您的评论，我认为您需要一种验证属性的通用方法，否则您的CollectErrors方法很快就会变得丑陋。
尝试从我使用Prism开发的项目中采用这种方法。此代码应该进入您的BaseModel类。
private bool TryValidateProperty(PropertyInfo propertyInfo, List<string> propertyErrors)
{
var results = new List<ValidationResult>();
var context = new ValidationContext(this) { MemberName = propertyInfo.Name };
var propertyValue = propertyInfo.GetValue(this);
// Validate the property
var isValid = Validator.TryValidateProperty(propertyValue, context, results);
if (results.Any()) { propertyErrors.AddRange(results.Select(c => c.ErrorMessage)); }
return isValid;
}
/// <summary>
/// Is called by the indexer to collect all errors and not only the one for a special field.
/// </summary>
/// <remarks>
/// Because <see cref="HasErrors" /> depends on the <see cref="Errors" /> dictionary this
/// ensures that controls like buttons can switch their state accordingly.
/// </remarks>
private void CollectErrors()
{
Errors.Clear();
PropertyInfos.ForEach(
prop =>
{
//Validate generically
var errors = new List<string>();
var isValid = TryValidateProperty(prop, errors);
if (!isValid)
//As you're using a dictionary to store the errors and the key is the name of the property, then add only the first error encountered.
Errors.Add(prop.Name, errors.First());
});
// we have to this because the Dictionary does not implement INotifyPropertyChanged
OnPropertyChanged(nameof(HasErrors));
OnPropertyChanged(nameof(IsOk));
// commands do not recognize property changes automatically
OnErrorsCollected();
}