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Code Issues 1 Projects 1 Releases Wiki Activity

improvements persisting view model properties

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Holger Börchers
2020-02-24 21:31:20 +01:00
parent 59d711da53
commit 046639681f
4 changed files with 74 additions and 45 deletions
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33
MvvmStuff/BaseViewModel.cs
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@ -11,16 +11,17 @@ namespace ModernWpfPlayground.MvvmStuff
{
public abstract class BaseViewModel : INotifyPropertyChanged
{
private readonly Dictionary<string, object> _values = new Dictionary<string, object>();
private readonly Dictionary<string, object> _valueDict = new Dictionary<string, object>();
public IReadOnlyDictionary<string, object> Values => _values;
protected bool SetProperty<T>(T value, Action<T>? onChanged = null,
[CallerMemberName] string? propertyName = null)
{
if(propertyName == null) throw new ArgumentNullException(nameof(propertyName));
if (_valueDict.TryGetValue(propertyName, out var obj) && Equals(value, obj)) return false;
if (_values.TryGetValue(propertyName, out var obj) && Equals(value, obj)) return false;
_valueDict[propertyName] = value!;
_values[propertyName] = value!;
OnPropertyChanged(propertyName);
onChanged?.Invoke(value);
return true;
@ -29,7 +30,7 @@ namespace ModernWpfPlayground.MvvmStuff
protected T GetProperty<T>(T defaultValue = default, [CallerMemberName] string? propertyName = null)
{
if (propertyName == null) throw new ArgumentNullException(nameof(propertyName));
return _valueDict.TryGetValue(propertyName, out var obj) ? (T) obj : defaultValue;
return Values.TryGetValue(propertyName, out var obj) ? (T) obj : defaultValue;
}
public event PropertyChangedEventHandler? PropertyChanged;
@ -42,32 +43,22 @@ namespace ModernWpfPlayground.MvvmStuff
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
protected void SaveViewModel()
{
var contents = JsonSerializer.Serialize(_valueDict);
var saveFileDialog = new SaveFileDialog {AddExtension = true, DefaultExt = "*.json"};
var result = saveFileDialog.ShowDialog(Application.Current.MainWindow?.Owner);
if (result == true)
{
File.WriteAllText(saveFileDialog.FileName, contents);
}
}
protected void ResetViewModel()
{
foreach (var key in _valueDict.Keys)
foreach (var key in Values.Keys)
{
_valueDict.Remove(key);
_values.Remove(key);
OnPropertyChanged(key);
}
}
protected void MapDictionary(IEnumerable<(string, object?)> tuples)
protected abstract IEnumerable<(string key, object? value)> GetViewModelItems();
protected void LoadViewModel()
{
if (tuples == null) throw new ArgumentNullException(nameof(tuples));
foreach (var (key, value) in tuples)
foreach (var (key, value) in GetViewModelItems())
{
_valueDict[key] = value!;
_values[key] = value!;
OnPropertyChanged(key);
}
}