MVVM可编辑ComboBox绑定 [英] MVVM Editable ComboBox Bindings

问题描述

这是我的问题...我有一个服务器列表，每个服务器都有一个ID和ServerName.我希望能够从ComboBox中选择一台服务器并在适当位置对其进行编辑，然后使其ID可用于稍后通过SQL更新.因此，假设这是数据:(ID = 1，名称="Server1")，(ID = 2，名称="Server2")，(ID = 3，名称="Server3").如果我从ComboBox中选择Server3，我想将其编辑为"Server4"，然后使用SQL查询将其上传(我知道该如何做).我正在使用MVVM，因此所有值都是我的ViewModel的属性.

Here's my issue...I have a list of servers, each with an ID and ServerName. I want to be able to select a server from the ComboBox and edit it in place, then have its ID available to update via SQL later. So let's say this is the data: (ID=1, Name="Server1"), (ID=2, Name="Server2"), (ID=3, Name="Server3"). If I select Server3 from the ComboBox, I'd like to edit it to be "Server4" then upload that with a SQL query (I know how to do this part). I'm utilizing MVVM, so all the values are properties of my ViewModel.

当前，当在ComboBox中修改文本字段时，SelectedServer立即变为null，大概是因为它不再是它可以识别的值.我可以使用一些指导来了解如何使它完成我想做的事情.

Currently, when the text field is modified in the ComboBox the SelectedServer immediately becomes null, presumably because it is no longer a value it recognizes. I could use some guidance on how to get this to do what I'm trying to do.

<ComboBox Grid.Column="1" x:Name="serverNameUpdateBox" HorizontalAlignment="Stretch" Height="23" VerticalAlignment="Center" IsEditable="True"
                          ItemsSource="{Binding Path=DataContext.SelectedProjectServers, ElementName=main}"
                          DisplayMemberPath="ServerName"
                          SelectedValue="{Binding SelectedServer}"
                          SelectedValuePath="ServerName"
                          Text="{Binding SelectedServer.ServerName, UpdateSourceTrigger=LostFocus}"
                          />

与ViewModel相关的代码:

And ViewModel relevant code:

namespace ViewModel
{
    public class ViewModel : INotifyPropertyChanged
    {
        public ViewModel()
        {
            SelectedProjectServers = new List<Server>();
            SelectedServer = new Server();


            private Server _selectedServer;

            public Server SelectedServer
            {
                get { return _selectedServer; }
                set
                {
                    if (value == null) { ModifiedServer = _selectedServer; }
                    _selectedServer = value;
                    RaisePropertyChanged("SelectedServer");
                }
            }


            private List<Server> _selectedProjectServers;

            public List<Server> SelectedProjectServers
            {
                get { return _selectedProjectServers; }
                set
                {
                    _selectedProjectServers = value;
                    RaisePropertyChanged();
                }
            }
        }
    }
}

与模型相关的代码:

namespace Model
{
    public class Server : INotifyPropertyChanged
    {
        private string _serverName;

        public string ServerName
        {
            get { return _serverName; }
            set
            {
                _serverName = value;
                RaisePropertyChanged();
            }
        }

        private int _serverID;

        public int ServerID
        {
            get { return _serverID; }
            set
            {
                _serverID = value;
                RaisePropertyChanged();
            }
        }


        public event PropertyChangedEventHandler PropertyChanged;
        private void RaisePropertyChanged([CallerMemberName] string caller = null)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(caller));
        }
    }
}

推荐答案

将"EditedServerName"之类的属性绑定到Combobox.Text.更改"EditedServerName"后，可以将值设置为SelectedServer的"ServerName".

Bind a property like "EditedServerName" to Combobox.Text. When the "EditedServerName" is changed you can set the value to the "ServerName" of your SelectedServer.

<ComboBox Grid.Column="1" x:Name= "serverNameUpdateBox" HorizontalAlignment= "Stretch" Height= "23" VerticalAlignment= "Center" IsEditable= "True"
ItemsSource= "{Binding Path=DataContext.SelectedProjectServers, ElementName=main}"
DisplayMemberPath= "ServerName"
SelectedItem="{Binding SelectedServer}"
Text= "{Binding EditedServerName, UpdateSourceTrigger=LostFocus}"
/>

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