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すべて！ MVVMとmySqlデータベースを使用してWPFアプリケーションを構築しています。私は、プロパティに格納されているComboBoxからSelectedItemを取得するのが困難です。基本的には、この時点で、SelectedItemをテキストボックスに表示したいと思います。それは、私がまだ学んでいるように、Bindingプロセスをより良く理解するのに役立ちます。WPF MVVM Combobox SelectionChanged/SelectedItem
最終的には、DBから別の値を引き出すための参照として格納された値/プロパティを使用したいと思います。以下にいくつかのサンプルコードを示します。どんな助けでも大歓迎です。ありがとうございました！
VIEW
<Grid Background="AliceBlue">
<Label Content="Street Address" HorizontalAlignment="Left" Margin="10,54,0,0" VerticalAlignment="Top" Width="87" Height="28"/>
<Label Content="State" HorizontalAlignment="Left" Margin="10,125,0,0" VerticalAlignment="Top" Width="87" Height="22"/>
<TextBox Name="txtStreetAddress" HorizontalAlignment="Left" Height="23" Margin="119,55,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"
Text="{Binding StreetAddress, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
/>
<ComboBox Name="cboState"
HorizontalAlignment="Left" Margin="119,125,0,0" VerticalAlignment="Top" Width="52"
DisplayMemberPath="StateAbb"
ItemsSource="{Binding StateAbbList}"
SelectedItem="{Binding SelectedStateAbb, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
/>
<TextBox HorizontalAlignment="Left" Height="23" Margin="180,124,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="59"
Text="{Binding SelectedStateAbb, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
/>
</Grid>
ビューモデル
public class AddStreetAddressVM : ObservableObject, IPageViewModel
{
public string Name
{
get
{
return "Add Street Address";
}
}
const string dbConnectionString = @"datasource=localhost;port=3306;Initial Catalog='optest1a1';username=root;password=";
private ICommand _cboStateAbb;
private string _streetAddress;
private ObservableCollection<tblStateAbb> _stateAbbList;
private string _selectedStateAbb;
private int _selectedStateNum;
public ICommand CboStateAbb
{
get
{
if (_cboStateAbb == null)
{
_cboStateAbb = new RelayCommand(param => this.fillStateAbb(), null);
}
return _cboStateAbb;
}
}
public string StreetAddress
{
get { return _streetAddress; }
set { SetProperty(ref _streetAddress, value,() => StreetAddress); }
}
public ObservableCollection<tblStateAbb> StateAbbList
{
get { return _stateAbbList; }
set
{
SetProperty(ref _stateAbbList, value,() => StateAbbList);
}
}
public string SelectedStateAbb
{
get { return _selectedStateAbb; }
set
{
SetProperty(ref _selectedStateAbb, value,() => SelectedStateAbb);
//if (_selectedStateAbb != null)
//{
// GetStateNum();
//}
//_selectedStateAbb = value;
}
}
public int SelectedStateNum
{
get { return _selectedStateNum; }
set { SetProperty(ref _selectedStateNum, value,() => SelectedStateNum); }
}
public AddStreetAddressVM() : base()
{
StateAbbList = new ObservableCollection<tblStateAbb>();
fillStateAbb();
}
private void fillStateAbb()
{
using (MySqlConnection con = new MySqlConnection(dbConnectionString))
{
StateAbbList = new ObservableCollection<tblStateAbb>();
con.Open();
string Query = "SELECT * FROM tbl_states";
MySqlCommand createCommand = new MySqlCommand(Query, con);
MySqlDataReader dr = createCommand.ExecuteReader();
int count = 1;
while (dr.Read())
{
string StateAbb = dr.GetString(2);
tblStateAbb stateabb = new tblStateAbb(count, StateAbb);
StateAbbList.Add(stateabb);
count++;
}
con.Close();
}
}
private void GetStateNum()
{
using (MySqlConnection con = new MySqlConnection(dbConnectionString))
{
con.Open();
string Query = "SELECT State_Num FROM tbl_states WHERE State_Abb='" + SelectedStateAbb + "' ";
MySqlCommand createCommand = new MySqlCommand(Query, con);
MySqlDataReader dr = createCommand.ExecuteReader();
int count = 1;
while (dr.Read())
{
int StateNum = dr.GetInt32(1);
StateNum = SelectedStateNum;
}
con.Close();
}
}
}
モデル - 国家略語
public class tblStateAbb : ObservableObject
{
private Int32 _count;
private String _stateAbb;
private Int32 _stateNum;
private ObservableCollection<tblStateAbb> _tblStateAbb;
public Int32 Count
{
get { return _count; }
set { SetProperty(ref _count, value,() => Count); }
}
public String StateAbb
{
get { return _stateAbb; }
set { SetProperty(ref _stateAbb, value,() => StateAbb); }
}
public Int32 StateNum
{
get { return _stateNum; }
set { SetProperty(ref _stateNum, value,() => StateNum); }
}
public ObservableCollection<tblStateAbb> StateAbbList
{
get { return _tblStateAbb; }
set { SetProperty(ref _tblStateAbb, value,() => StateAbbList); }
}
public tblStateAbb() : base()
{
Count = 0;
StateAbb = "";
StateAbbList = new ObservableCollection<tblStateAbb>();
}
public tblStateAbb(int count, string stateabb) : base()
{
Count = count;
StateAbb = stateabb;
StateAbbList = new ObservableCollection<tblStateAbb>();
}
public tblStateAbb(int count, string stateabb, int statenum) : base()
{
Count = count;
StateAbb = stateabb;
StateNum = statenum;
StateAbbList = new ObservableCollection<tblStateAbb>();
}
}
被監視オブジェクト（INotifyPropertyChange）
public abstract class ObservableObject : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propName)
{
Debug.Assert(GetType().GetProperty(propName) != null);
var pc = PropertyChanged;
if (pc != null)
{
pc(this, new PropertyChangedEventArgs(propName));
}
}
protected bool SetProperty<T>(ref T field, T value, string propName)
{
if (!EqualityComparer<T>.Default.Equals(field, value))
{
field = value;
OnPropertyChanged(propName);
return true;
}
return false;
}
protected bool SetProperty<T>(ref T field, T value, Expression<Func<T>> expr)
{
if (!EqualityComparer<T>.Default.Equals(field, value))
{
field = value;
var lambda = (LambdaExpression)expr;
MemberExpression memberExpr;
if (lambda.Body is UnaryExpression)
{
var unaryExpr = (UnaryExpression)lambda.Body;
memberExpr = (MemberExpression)unaryExpr.Operand;
}
else
{
memberExpr = (MemberExpression)lambda.Body;
}
OnPropertyChanged(memberExpr.Member.Name);
return true;
}
return false;
}
}
relayコマンド
public class RelayCommand : ICommand
{
private Action<object> execute;
private Func<object, bool> canExecute;
public event EventHandler CanExecuteChanged
{
add { CommandManager.RequerySuggested += value; }
remove { CommandManager.RequerySuggested -= value; }
}
public RelayCommand(Action<object> execute, Func<object, bool> canExecute = null)
{
this.execute = execute;
this.canExecute = canExecute;
}
public bool CanExecute(object parameter)
{
return this.canExecute == null || this.canExecute(parameter);
}
public void Execute(object parameter)
{
this.execute(parameter);
}
}
あなたは助けが必要であり、あなたが投稿したすべてのコードを読むように求めているのは公正だと思いますか？問題を絞り込んで、コードのその部分だけを投稿してください。 – CodingYoshi
興味のある部分を読んでみませんか？私がビューを投稿するだけだと思うなら、Viewだけを読んで、他のものはすべて無視してください。いいえ？ – Progolfer79
公正であるために、私はそれを読むことに興味がありません。そして正直言って、他のほとんどの人たちも興味がありません。私が作っていることは、あなたの質問に少しでも力を入れて、人々があなたを助けるために簡単にできるようにすることです。今は簡単ではありません。それは理にかなっていますか？ – CodingYoshi