所以我试图使用WPF和MVVM光来构建一个小的cookbook应用程序。我遇到了将List从模型绑定到视图模型的情况。它适用于显示和删除项目,但在添加项目时,我无法让显示更新。
我遇到了ObserableCollections,这似乎正是我想要的,但我不确定我是否正确使用它们,因为每次创建新的OC似乎都是错误的。当模型使用列表时,我应该如何检索可观察的集合?
模型(或多个):
public class Recipe
{
public int Id { get; set; }
public string Title { get; set; }
public List<RecipeIngredient> Ingredients { get; set; }
}
public class RecipeIngredient
{
// ... //
}
视图模型:
public Recipe SelectedRecipe
{
get
{
return this.selectedRecipe;
}
set
{
this.selectedRecipe = value;
RaisePropertyChanged("SelectedRecipe");
RaisePropertyChanged("RecipeIngredients");
}
}
public ObservableCollection<RecipeIngredient> RecipeIngredients
{
get
{
return new ObservableCollection<RecipeIngredient>(selectedRecipe.Ingredients.ToList());
}
}
public RelayCommand<EventArgs> AddIngredientCommand { get; private set; }
public RelayCommand<string> DeleteIngredientCommand { get; private set; }
private void AddIngredient(EventArgs eventArgs)
{
SelectedRecipe.Ingredients.Add(new RecipeIngredient() { Name = "New Ingredient" });
RaisePropertyChanged("RecipeIngredients");
}
private void DeleteIngredient(string name)
{
SelectedRecipe.Ingredients = SelectedRecipe.Ingredients.Where(i => i.Name != name).ToList();
RaisePropertyChanged("RecipeIngredients");
}
public MainViewModel()
{
DBController db = new DBController();
recipes = db.GetRecipeList();
RecipeSelectionChangedCommand = new RelayCommand<SelectionChangedEventArgs>((args) => RecipeSelectionChanged(args));
SaveRecipeCommand = new RelayCommand<EventArgs>((args) => SaveRecipe(args));
AddIngredientCommand = new RelayCommand<EventArgs>((args) => AddIngredient(args));
DeleteIngredientCommand = new RelayCommand<string>((args) => DeleteIngredient(args));
}
我离开这里了吗?
答案 0 :(得分:4)
应该仔细阅读。如果您在备用视图中显示所选配方的成分,则应在视图中使用数据绑定<ListBox ItemsSource="{Binding SelectedRecipe.Ingredients}"/>
您可以考虑将ORQ实体(实体框架)用于ORM ..
public class RecipeVM
{
public RecipeVM(Recipe r)
{
recipe = r;
}
Recipe recipe;
public int Id
{
get
{
return recipe.Id;
}
set
{
PropertyChanged("Id");
recipe.id = value;
}
}
public string Title
{
get
{
return recipe.Title;
}
set
{
PropertyChanged("Title");
recipe.Title = value;
}
}
ObservableCollection<RecipeIngredient> ingredients;
public ObservableCollection<RecipeIngredient> Ingredients
{
get
{
if (ingredients == null)
ingredients = new ObservableCollection<RecipeIngredient>(recipe.Ingredients);
return ingredients;
}
set
{
PropertyChanged("Ingredients");
ingredients = value;
}
}
}
如果你想保持集合同步,你需要稍微修改一下..