TreeView MVVM ObservableCollection更新

每个部门的小时数取决于其团队的总小时数。每个小组的时间取决于其个人时间的总和。因此,每个团队都应该听取其个人的 Hours 财产。当检测到时,它应该上升 OnPropertyChanged 为了自己 小时 财产。同样,每个 Department 应该听取其团队的任何更改 小时 财产。当检测到时,它应该上升 OnProperty已更改 为了自己 小时 财产。

最终结果是,改变任何个人(或团队)的工作时间都会反映在家长中。

通过重构可以大大改进的psedo代码,但给出了答案的本质:

public class Individual : ViewModel
{
    public int Hours
    {
        // standard get / set with property change notification
    }

}

public class Team : ViewModel
{
    public Team()
    {
        this.individuals = new IndividualCollection(this);
    }

    public ICollection<Individual> Individuals
    {
        get { return this.individuals; }
    }

    public int Hours
    {
        get
        {
            // return sum of individual's hours (can cache for perf reasons)
        }
    }

    // custom collection isn't strictly required, but makes the code more readable
    private sealed class IndividualCollection : ObservableCollection<Individual>
    {
        private readonly Team team;

        public IndividualCollection(Team team)
        {
            this.team = team;
        }

        public override Add(Individual individual)
        {
            individual.PropertyChanged += IndividualPropertyChanged;
        }

        public override Remove(...)
        {
            individual.PropertyChanged -= IndividualPropertyChanged;
        }

        private void IndividualPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            if (e.PropertyName == "Hours")
            {
                team.OnPropertyChanged("Hours");
            }
        }
    }
}

public class Department : ViewModel
{
    public Department()
    {
        this.teams = new TeamCollection();
    }

    public ICollection<Team> Teams
    {
        get { return this.teams; }
    }

    public int Hours
    {
        get
        {
            // return sum of team's hours (can cache for perf reasons)
        }
    }

    // TeamCollection very similar to IndividualCollection (think generics!)
}

请注意,如果性能成为一个问题,您可以让集合本身维护小时总数。这样,无论何时只要孩子 小时 属性更改,因为它被告知旧值和新值。因此,它知道应用于聚合的区别。

我很抱歉,您必须在每个人的父级(“团队”)的父级ObservableCollection容器上明确调用通知。

然后,从单个父级,为“大父级”(“部门”)设置通知事件。

Team.OnPropertyChanged("Individuals")