Wpf来自数据库绑定的C＃combobox itemssource [英] Wpf C# combobox itemssource from database binding

问题描述

好的，这就是问题 - 我会尽力解释它。



我有两种方法从数据库中提取两个不同的字段/值：类型和状态。这些方法正在运行并为每个方法输出正确的值。在XAML页面上，我有三个组合框。示例：

Ok, here's the problem - and I'll do my best to actually explain it.

I have two methods pulling two different fields/values form the database: Type and Status. The methods are working and oulling the correct values for each. On the XAML page, I have three comboboxes. Example:

<ComboBox x:Name="CbType" HorizontalAlignment="Right" Margin="0,10,18.2,0" VerticalAlignment="Top" Width="120" ItemsSource="{Binding}" />

<ComboBox x:Name="CbStatus" HorizontalAlignment="Left" Margin="89,91,0,77.4"
Width="120" ItemsSource="{Binding}" d:LayoutOverrides="Height" />

问题是ItemsSource ={Binding}。我认为，绑定应该看起来像ItemsSource ={Binding Type}和ItemsSource ={Binding Statuses}。我无法弄清楚如何将这个名称设置为绑定。如果没有为每个Binding提供不同的值，我在组合框中根本没有得到任何值。如果我在XAML中取出第二个方法和第二个ItemSource，它只适用于其中一个组合框。我认为代码不知道如何区分两者，那么如何帮助它理解呢？ :)



以下是该方法的示例：

The problem is the ItemsSource="{Binding}". Binding, I think, should look something like ItemsSource="{Binding Type}" and ItemsSource="{Binding Statuses}". I can't figure out how to set this "names" to the binding. Without suppling a different value for each Binding, I get no values at all in the combobox. If I take out the second method and second ItemSource in the XAML, it works for only one of the comboboxes. I think the "code" doesn't know how to differeniate between the two, so how to do I help it understand? :)

Here is an example of the method:

public void GetAddrTypes()
        {
            //***Set Variables***

            var preSql = Settings.Default.GetAddrTypes;
            var sql = preSql;

            Log.Debug("SP: " + preSql + " for GetAddrTypes()");
            Log.Debug("Dbconn called and created for GetAddrTypes()");

            var connectionString = Settings.Default.Dbconn;
            using (var conn = new SqlConnection(connectionString))
                //using (var cmd = new SqlCommand(sql, conn))
            {
                try
                {
                    conn.Open();
                    var adpter = new SqlDataAdapter(sql, conn);
                    var ds = new DataSet();
                    adpter.Fill(ds);
                    CbType.DataContext = ds.Tables[0];
                    CbType.DisplayMemberPath = "AddrTypeCode";
                    CbType.SelectedValuePath = "AddrTypeCode";
                    Log.Debug("Command executed and reader completed for GetAddrTypes()");
                }
                catch (SqlException ex)
                {
                    // Build custom message box for exception upload
                    var msg = ex.ToString();
                    var title = DataLogic.Properties.Resources.CustomMsgBxTitle;
                    MessageBoxManager.Ok = "Copy";
                    MessageBoxManager.Cancel = "Ignore";
                    MessageBoxManager.Register();
                    var result = MessageBox.Show(msg, title, MessageBoxButtons.OKCancel,
                        MessageBoxIcon.Hand);
                    switch (result)
                    {
                        case System.Windows.Forms.DialogResult.OK:
                            Clipboard.SetText(msg);
                            break;
                        case System.Windows.Forms.DialogResult.Cancel:
                            break;
                    }
                    MessageBoxManager.Unregister();
                    Log.Error("Exception Thrown: " + msg + " - for while calling GetAddrTypes");
                }
                finally
                {
                    Log.Info("Closing SQL Connection for GetAddrTypes()");
                }
            }
        }

这是页面加载

Here is the Page Load

private void MetroWindow_Loaded(object sender, RoutedEventArgs e)
       {
           TbId.Text = Idval;
           CbType.SelectedValue = Typeval;
           TbDesc.Text = Descval;
           CbStatus.SelectedValue = Statval;
           CbSysReq.SelectedValue = Sysreqval;
           GetAddrTypes();
           GetStatusCodes();
       }

我尝试过：



public ObservableCollection<> 名字{得到;组; }

但这些是我正在调用的类。

What I have tried:

public ObservableCollection<> "name" { get; set; }
But these are classes I'm calling.

推荐答案

绑定的基本原理是使用列表在视图模型中创建数据。我将在这里解释一下。



1.）创建一个示例类：

Hi,

The basic of binding this would be using a list to create the data in view model. I will try to explain it here.

1.) Create a sample class :

public class ComboData : INotifyPropertyChanged
    {
        private string _text { get; set; }
        private string _values { get; set; }

        public string Text
        {
            get { return _text; }
            set
            {
                _text = value;
                OnPropertyChanged("Text");
            }
        }

        public string Values
        {
            get { return _values; }
            set
            {
                _values = value;
                OnPropertyChanged("Value");
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void OnPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }

2.）在你的班级中添加两个列表的属性：

2.) In your class add the properties for two lists:

List<ComboData> _typeList = new List<ComboData>();

       public List<ComboData> TypeList
       {
           get { return _typeList; }
           set
           {
               _typeList = value;
               RaisePropertyChanged(() => TypeList);
           }
       }

       List<ComboData> _statusList = new List<ComboData>();

       public List<ComboData> StatusList
       {
           get { return _statusList; }
           set
           {
               _statusList = value;
               RaisePropertyChanged(() => StatusList);
           }
       }

这两个属性在我的视图模型中。如果你想知道什么是RaisePropertyChanged（），它是我的ViewModelBase的实现。



我的示例ViewModelBase可以是：

These two properties are in my view model. If you are wondering what is RaisePropertyChanged() here, it is the implementation for my ViewModelBase.

My sample ViewModelBase can be like:

public abstract class ViewModelBase : INotifyPropertyChanged
    {
        protected void RaisePropertyChanged<T>(Expression<Func<T>> action)
        {
            var propertyName = GetPropertyName(action);
            RaisePropertyChanged(propertyName);
        }

        private static string GetPropertyName<T>(Expression<Func<T>> action)
        {
            var expression = (MemberExpression)action.Body;
            var propertyName = expression.Member.Name;
            return propertyName;
        }

        public void RaisePropertyChanged(string propertyName)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }

        public event PropertyChangedEventHandler PropertyChanged;        
    }

3.）在视图模型构造函数中创建示例数据。如果你没有使用mvvm方法，请在你的Loaded事件中创建：

3.) Create a sample data in your view model constructor. If you are not using mvvm approach, create this in your Loaded event:

TypeList.Add(new ComboData {Text = "1234", Values = "1234"});
TypeList.Add(new ComboData {Text = "1234", Values = "41234"});

StatusList.Add(new ComboData {Text = "agfasd", Values = "asgas"});
StatusList.Add(new ComboData {Text = "ag", Values = "asdg"});

基本上，这里我们有一个text属性，用于显示绑定值为其成员路径的值。



4.）在你的xaml中添加ComboBox：

So basically, here we have a text property that will be for display binded with a value for its value member path.

4.) Add the ComboBox in your xaml:

<combobox grid.row="1" grid.column="1" x:name="CbType" itemssource="{Binding TypeList}" displaymemberpath="Text" selectedvaluepath=" Values" xmlns:x="#unknown" />

这应该有效。



尝试在谷歌搜索并查看绑定组合框的基础知识。



希望这有帮助！

This should work.

Try searching on google and see what are basics of binding a combobox.

Hope this helps !

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