UpdateSourceTrigger为显式MVVM [英] UpdateSourceTrigger to explicit MVVM

问题描述

大家好，



我有一个修改实体的视图模型，我想在用户按下保存按钮时更新源，所以我设置了UpdateSourceTrigger显式，但现在我如何更新MVVM模式中的源？



使用显式绑定，一直期望使用BindingExpression更新绑定源。



我也试过带参数的继电器命令。但这一切都是基于假设。



告诉我。在此先感谢

解决方案

在这种情况下，我通常会有一个编辑视图模型，它会复制所有可编辑的属性，然后绑定到那些。保存按钮会将可编辑属性复制到模型的属性中。



假设具有属性的模型名称：和年龄将具有带EditableName的视图模型和EditableAge。



如果我的视图模型仅用于编辑视图，那么我可能只是使用一个视图模型，在其构造函数中获取模型，将属性复制到vm的属性中（即：不直接转发/写入模型）并在视图模型中保留名称Name和Age。



这样做有意义吗？

请在.XAML窗口的事件OnPreviewKeyDown中写下此代码：



if（e.Key == Key.Enter）

{

var focusedElement = Keyboard.FocusedElement as FrameworkElement;



if（focusedElement是TextBox）

{

var expression = focusedElement.GetB indingExpression（TextBox.TextProperty）;

if（表达式！= null）expression.UpdateSource（）;

}

}

Hi all,

I have a view model to modify an entity and i want update the source when the user press save button so I’ve set the UpdateSourceTrigger to explicit but now how can i update the source in MVVM pattern?

With explicit binding, this has always been expected to update the binding source using BindingExpression.

I have tried relay command with parameters also. But it all goes by assumption.

Advise me. Thanks in advance

解决方案

In cases like that, I usually have an editing view model, that makes a copy of all the properties that are editable, and I bind to those. The save button will copy the editable properties into the model's properties.

Say a model with properties "Name: and "Age" will have a view model with "EditableName" and "EditableAge."

If my view model was solely for the editing view, then I'd probably just use a view model that takes the model in its constructor, copies the properties into the vm's properties (ie: doesn't directly forward / write to model) and keep the names Name and Age in the view model.

Does that make sense?

Please write this code in event "OnPreviewKeyDown" of your .XAML window:

if (e.Key == Key.Enter)
{
var focusedElement = Keyboard.FocusedElement as FrameworkElement;

if (focusedElement is TextBox)
{
var expression = focusedElement.GetBindingExpression(TextBox.TextProperty);
if (expression != null) expression.UpdateSource();
}
}

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