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Presentation Model (MVVM) Good Practices

, 11 May 2010
Showing some good practices that can be applied to the Presentation Model/MVVM pattern.
PresentationModelDemo.zip
App.Configuration
App.Configuration.Wpf
Interceptors
Properties
Wpf
Properties
Wpf
App.Core
Model
PresentationModel
Properties
Services
App.Data
Properties
libs
AttachedCommandBehavior.dll
Castle.Core.dll
Castle.DynamicProxy2.dll
Castle.MicroKernel.dll
Castle.Windsor.dll
PresentationModelBase
Properties
WPFUI
Properties
Settings.settings
View
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel;
using PresentationModelBase;
using System.Reflection;

namespace App.Configuration.Wpf
{
    //this property will tell if the PresentationModel is doing
    //some work in background
    class IsWorkingPropertyDescriptor : PropertyDescriptor
    {
        public IsWorkingPropertyDescriptor() :
            base(
             TypeDescriptor.CreateProperty
             (typeof(PresentationModel), "IsWorking", typeof(bool), null))
        {
            _propertyChangeNotification = typeof(PresentationModel).GetMethod("OnPropertyChanged", BindingFlags.NonPublic | BindingFlags.Instance);
        }

        MethodInfo _propertyChangeNotification;
        static Dictionary<PresentationModel, bool> _propertyValues = new Dictionary<PresentationModel, bool>();

        public override bool CanResetValue(object component)
        {
            return true;
        }

        public override Type ComponentType
        {
            get { return typeof(PresentationModel); }
        }

        public override object GetValue(object component)
        {
            PresentationModel pm = (PresentationModel)component;
            if (!_propertyValues.ContainsKey(pm))
            {
                _propertyValues.Add(pm, false);
            }
            return _propertyValues[pm];
        }

        public override bool IsReadOnly
        {
            get { return false; }
        }

        public override Type PropertyType
        {
            get { return typeof(bool); }
        }

        public override void ResetValue(object component)
        {
            SetValue(component, false);
        }

        public override void SetValue(object component, object value)
        {
            PresentationModel pm = (PresentationModel)component;
            if (!_propertyValues.ContainsKey(pm))
            {
                _propertyValues.Add(pm, (bool)value);
            }
            else
                _propertyValues[pm] = (bool)value;
            _propertyChangeNotification.Invoke(component, new object[] { "IsWorking" });
        }

        public override bool ShouldSerializeValue(object component)
        {
            return false;
        }
    }
}

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Web03 | 2.8.140821.2 | Last Updated 11 May 2010
Article Copyright 2010 by Thiago de Arruda
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