WPF 用户控件与父视图/视图模型的交互 [英] WPF Usercontrol interaction with parent view / viewmodel

问题描述

您好，我有一个 mainView 窗口，它的 dataContext 设置为它自己的 viewModel.

Hi I have a mainView window which has its dataContext set to it's own viewModel.

在该 viewModel 上有一个 DateTime 属性，该属性又使用 2 路绑定绑定到我的主视图上的日期选择器.

On that viewModel is a DateTime property which in turn is bound to a datepicker on my main view using 2 way binding.

<toolkit:DatePicker DateSelected="{Binding mainDateTimeProperty, Mode=TwoWay}" />

到目前为止一切都很好.在更改我的日期时间属性时，我创建了一个列表，然后将其绑定到主视图上其他地方的数据网格.这一切都很好.

This is all fine so far. On the change of my datetime property I create a list which is then bound to a datagrid elsewhere on the mainview. This all works fine.

我的问题是关于我想添加到主视图的用户控件.我希望这个用户控件是自包含的，所以用它自己的视图模型创建了它，但它也需要访问 mainDateTimeProperty

My question is to do with a usercontrol I want to add to the main view. I want this usercontrol to be self contained so have created it with it's own viewmodel but it does also need access to mainDateTimeProperty

我认为最好的方法是在用户控件上创建一个 dependencyProperty，当我在主视图中创建我的控件时，我将 dp 绑定到日期时间，如下所示.

I thought that best way to go would be to create a dependencyProperty on the usercontrol and when I create my control in the main view I bind the dp to the datetime as follows.

<uc:MyNewUserControl DateProperty="{Binding mainDateTimeProperty}" />

问题是我如何让用户控件使用它的视图模型维护数据上下文，但仍然将依赖属性绑定到主视图模型上的属性?

Trouble is how do I have the usercontrol maintain datacontext with it's viewmodel and yet still have the dependency property bound to a property on the main view model?

希望这很清楚.如有必要，可以发布更多代码.如果可能，寻找最佳实践方法.

Hope this is clear. Can post some more code if necessary. Looking for a best practice approach if possible.

非常感谢您的建议.

推荐答案

试试

<uc:MyNewUserControl DateProperty="{Binding Parent.DataContext.mainDateTimeProperty, Mode=TwoWay}" />

抱歉，previos 代码不正确.正确的绑定是

Edited: Sorry, previos code was incorrect. Correct binding is

<uc:MyNewUserControl DateProperty="{Binding Path=Parent.DataContext.mainDateTimeProperty, RelativeSource={RelativeSource Self}, Mode=TwoWay} />

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