Does some validation of the properties and has some structures to display the errors
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel;
namespace MvvmFoundation.Wpf
{
/// <summary>
/// ViewModelBase with Validation via IDataErrorInfo.
/// </summary>
public abstract class ValidationViewModelBase : ObservableObject, IDataErrorInfo
{
#region IDataErrorInfo Code
/// <summary>
/// Implement this in the Implementing Class. Throw an exception to allow validation to show on the UI.
/// </summary>
/// <param name="propertyName">The Property to Validate</param>
public abstract string this[string propertyName] { get; }
/// <summary>
/// IDataErrorInfo.Error
/// </summary>
public string Error
{
get
{
if (HasValidationErrors)
return "Invalid";
else
return "";
}
}
/// <summary>
/// Add an Error
/// </summary>
/// <param name="key">The key of the Error</param>
/// <param name="value">The Value/Reason of the Error</param>
public void AddError(string key, string value)
{
RemoveError(key);
errorMessages.Add(key, value);
RaisePropertyChanged("ValidationErrors");
RaisePropertyChanged("HasValidationErrors");
}
/// <summary>
/// Remove an Error by key
/// </summary>
/// <param name="key">the error key to remove</param>
public void RemoveError(string key)
{
if (errorMessages.ContainsKey(key))
errorMessages.Remove(key);
RaisePropertyChanged("ValidationErrors");
RaisePropertyChanged("HasValidationErrors");
}
/// <summary>
/// String Representation of the Validation Errors
/// </summary>
public string ValidationErrors { get { return getErrorString(); } }
/// <summary>
/// Has Validation errors ?
/// </summary>
public bool HasValidationErrors { get { return errorMessages.Count > 0; } }
#region Implementation Details
private IDictionary<string, string> errorMessages = new Dictionary<string, string>();
private string getErrorString()
{
StringBuilder value = new StringBuilder();
foreach (KeyValuePair<string, string> item in errorMessages)
value.AppendLine(string.Format("{0} - {1}", item.Key, item.Value));
return value.ToString();
}
#endregion
#endregion
}
}
