无法使用xaml中定义的控件在背后的代码中使用DataTemplate创建内容 [英] Can't create content with DataTemplate in code behind with control defined in xaml

问题描述

我在ContentPage的xaml中的ResourceDictionary中具有以下标签:

I have the following label in a ResourceDictionary in xaml of my ContentPage:

<ContentPage.Resources>
       <ResourceDictionary>
            <Label Text="I am label" x:Name="label" x:Key="label"/>
       </ResourceDictionary>
</ContentPaget.Resources>

在我后面的代码中，我单击了以下事件处理程序:

And in in my code behind I have this clicked event handler:

void Handle_Clicked(object sender, System.EventArgs e)
    {
        DataTemplate dataTemplate = new DataTemplate(() => label);
        for (int i = 0; i < 3; i ++)
        {
            Label content = (Label) dataTemplate.CreateContent();
            stack.Children.Add(content);
        }
    }

在我的称为stack的StackLayout中-按下分配给Handle_Clicked的按钮时，仅添加1个标签.为什么只添加1个标签-应该添加3个标签?

In my StackLayout called stack - only 1 label is added when the button assigned with Handle_Clicked is pressed. Why is only 1 label added - when there should be 3 labels added?

推荐答案

我怀疑所有控件都需要唯一的ID.由于这也不起作用:

I suspect that all controls need a unique id. Since this was not working either:

void Handle_Clicked(object sender, System.EventArgs e)
{
    for (int i = 0; i < 3; i ++)
    {
        stack.Children.Add(label);
    }
}

这使我首先尝试使用DataTemplate.意味着同一对象只能添加到视图一次.

which had brought me to try and use DataTemplate in the first place. Meaning the same object can only be added once to the view.

还应注意，createContent()是有效的-但前提是它是在xaml中定义的(未在后面的代码中实例化):

It can also be noted that createContent() works - but only if it is being defined in xaml (not being instantiated in code behind):

<ContentPage.Resources>
       <ResourceDictionary>
            <DataTemplate x:Name="dataTemplate" x:Key="dataTemplate">
                <Label Text="I am label"/>
            </DataTemplate>
       </ResourceDictionary>
</ContentPaget.Resources>

---

我发现的解决方法是摆脱DataTemplate并在添加对象之前先克隆对象:

---

The workaround I found was to get rid of the DataTemplate and clone the object instead before adding it:

void Handle_Clicked(object sender, System.EventArgs e)
{
    for (int i = 0; i < 3; i ++)
    {
        var l = FastDeepCloner.DeepCloner.Clone(label);
        stack.Children.Add(l);
    }
}

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