依赖属性在加载时没有值

发布于 2024-09-04 00:23:18 字数 2278 浏览 2 评论 0原文

我的问题是这样的，我有一个名为 profile 的 UC，其中包含另一个名为 FollowImageControl 的 UC。

在我的 Profile.xaml 中，我声明性地将 FollowImageControl 的一个名为 FollowerId 的属性绑定到 Profile.xaml.cs 中的 CurrentUserId。问题是我的 CurrentUserId 是在 Profile.xaml.cs 中分配的； Profile.xaml 代码隐藏。

这意味着我最初并没有获得 FollowerId。我在 FollowImageControl.xaml.cs 中有这些方法：

    public static readonly DependencyProperty _followUserId =
                    DependencyProperty.Register("FollowUserId", typeof(Guid), typeof(FollowImageControl), null);
    public Guid FollowUserId
    {
        get { return (Guid)GetValue(_followUserId); }
        set { SetValue(_followUserId, value); }
    }
    public FollowImageControl()
    {
        // Required to initialize variables
        InitializeComponent();
        LoggedInUserId = WebContext.Current.User.UserId;
        var ctx = new NotesDomainContext();
        if (ctx.IsFollowingUser(LoggedInUserId, FollowUserId).Value) SwitchToDelete.Begin();
    }


    private void AddImg_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        if (LoggedInUserId != FollowUserId)
        {
            var ctx = new NotesDomainContext();
            ctx.FollowUser(FollowUserId, LoggedInUserId);
            ctx.SubmitChanges();
        }
    }

奇怪的事情，当我插入断点时，FollowImageControl() 中的 FollowerUserId 为 0，但它的值是AddImg_MouseLeftButtonDown，并且没有中间逻辑来设置它的值。这是怎么回事？？？

这是更多代码信息：

这是我来自 profile.xaml 的绑定，

<internalCtrl:FollowImageControl FollowUserId="{Binding ElementName=ProfileCtrl, Path=CurrentUserId}" />

这是我在 profile.xaml.cs 中的构造函数，其中设置了 CurrentUserId public static readonly DependencyProperty _CurrentUserId =

DependencyProperty.Register("CurrentUserId", typeof(Guid), typeof(Profile), null);
        public Guid CurrentUserId 
        {
            get { return (Guid)GetValue(_CurrentUserId); }
            set { SetValue(_CurrentUserId, value); }
        }

public Profile(Guid UserId) {
            CurrentUserId = UserId;
            InitializeComponent();
            Loaded += new RoutedEventHandler(Profile_Loaded);
        }

我非常惊讶，前一分钟 FollowerId 还没有值，下一分钟它就持有正确的值，而我却没有更改代码隐藏中的值。

原文

My problem is this, I have a UC called profile that contains another UC called FollowImageControl.

In my Profile.xaml i declaretively bind a property of FollowImageControl called FollowerId to a CurrentUserId from Profile.xaml.cs. Problem is that I CurrentUserId is assigned in Profile.xaml.cs; the Profile.xaml code-behind.

This means that I do not initially get the FollowerId. I have these methods in the FollowImageControl.xaml.cs:

    public static readonly DependencyProperty _followUserId =
                    DependencyProperty.Register("FollowUserId", typeof(Guid), typeof(FollowImageControl), null);
    public Guid FollowUserId
    {
        get { return (Guid)GetValue(_followUserId); }
        set { SetValue(_followUserId, value); }
    }
    public FollowImageControl()
    {
        // Required to initialize variables
        InitializeComponent();
        LoggedInUserId = WebContext.Current.User.UserId;
        var ctx = new NotesDomainContext();
        if (ctx.IsFollowingUser(LoggedInUserId, FollowUserId).Value) SwitchToDelete.Begin();
    }


    private void AddImg_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        if (LoggedInUserId != FollowUserId)
        {
            var ctx = new NotesDomainContext();
            ctx.FollowUser(FollowUserId, LoggedInUserId);
            ctx.SubmitChanges();
        }
    }

THE WEIRD THING IS that when i insert breakpoints the FollowerUserId in FollowImageControl() is 0, but it has a value in AddImg_MouseLeftButtonDown, and there is no inbetween logic that sets the value of it. How is this???

Here's a little more code info:

This is my binding from profile.xaml

<internalCtrl:FollowImageControl FollowUserId="{Binding ElementName=ProfileCtrl, Path=CurrentUserId}" />

this is my constructor in profile.xaml.cs wherein the CurrentUserId is set
public static readonly DependencyProperty _CurrentUserId =

DependencyProperty.Register("CurrentUserId", typeof(Guid), typeof(Profile), null);
        public Guid CurrentUserId 
        {
            get { return (Guid)GetValue(_CurrentUserId); }
            set { SetValue(_CurrentUserId, value); }
        }

public Profile(Guid UserId) {
            CurrentUserId = UserId;
            InitializeComponent();
            Loaded += new RoutedEventHandler(Profile_Loaded);
        }

I'm seriously dumbfound that one minute the FollowerId has no value, and the next it holds the right, without me having changed the value in the code-behind.

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三生路 2024-09-11 00:23:18

您在 FollowImageControl 构造函数中的何处设置断点？如果您在调用 InitializeComponent() 之前设置了它，这是正常行为，因为 InitializeComponent() 会执行所有 XAML。这意味着，您的绑定也是在此方法中创建的，因此在调用 InitializeComponent() 之后应该有一个值，而不是之前。当然，AddImg_MouseLeftButtonDown 在构造函数完成后被调用，因此 InitializeComponent() 也被调用。