Winforms ComboBox 2种方式进行数据绑定仅1种方式 [英] Winforms ComboBox 2 way databinding only works 1 way

问题描述

我有一个组合框，在设计视图中，它具有如下绑定到绑定源的数据：

I have a combobox, and in the design view I have it databound to a bindingsource as follows:

this.itemTypeComboBox.DataBindings.Add(new System.Windows.Forms.Binding("SelectedValue", this.itemTypeContainerBindingSource, "ItemType", true));
this.itemTypeComboBox.DataBindings.Add(new System.Windows.Forms.Binding("Text", this.itemTypeContainerBindingSource, "ItemType", true));

在load事件背后的代码中，我有以下内容：

In the code behind in the load event I have the following:

// bind the combobox to the enum
this.itemTypeComboBox.DataSource = Enum.GetValues(typeof(OpticalItemType));

// bind a custom object to the datasource
this.itemTypeContainerBindingSource.DataSource = customObjectContainer;

customObjectContainer是一个单个对象，其中包含绑定到组合框的属性 ItemType ，并且该对象的所有属性都通过 INotifyPropertyChanged使用更改通知。

The "customObjectContainer" is a single object that contains a property "ItemType" that is bound to the combobox, and all properties of the object use change notification through "INotifyPropertyChanged".

在我后面的代码中，如果我以编程方式更改自定义对象，则更改将反映在组合框中。但是，如果我通过UI更改组合框，则绑定源以及自定义对象均无法反映更改。

In my code behind, if I programmatically change the custom object, the changes are reflected in the combobox. However, if I change the combobox through the UI, the bindingsource, and hence the custom object do not reflect the changes.

有什么想法我做错了吗？

Any ideas what I am doing wrong?

由于它是单个对象，因此与使用BindingList等无关。

As it is a singular object, it cannot be to do with using BindingList etc.

好吧，每当我通过UI更改组合框时，它都不会更改基础对象，也不会为自定义对象中的属性命中设置方法。但是，我刚刚注意到，如果我退出该控件，它将触发设置器，并更改基础对象。为什么？

Ok, whenever I change the combobox through the UI, it never changes the underlying object, the setter is never hit for the property in the custom object. However, I have just noticed that if I tab off of the control, it then fires the setter, and changes the underlying object. Why would this be?

看来，问题出在我的约束力上。我在绑定中添加了 DataSourceUpdateMode.OnPropertyChanged，现在可以正常使用！

It appears, the issue was with my binding. I added "DataSourceUpdateMode.OnPropertyChanged" to the bindings, and it works now!!

推荐答案

问题出在我的绑定上。我在绑定中添加了 DataSourceUpdateMode.OnPropertyChanged，现在可以正常使用！

The issue was with my binding. I added "DataSourceUpdateMode.OnPropertyChanged" to the bindings, and it works now!!

这篇关于Winforms ComboBox 2种方式进行数据绑定仅1种方式的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！