按下按钮时不显示 C# 数据网格数据
本文关键字：数据 数据网 网格 显示 按钮 | 更新日期: 2023-09-27 18:36:22
我正在做一个WPF（MVVM）项目，当我按下按钮时尝试在数据网格中显示数据时遇到问题。我可以在构造函数上显示这些信息，但永远不会在软件初始化后显示这些信息（例如，当我按下按钮时）
这是 MA XAML ：
<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:dxe="http://schemas.devexpress.com/winfx/2008/xaml/editors"
x:Class="noteManager.MainWindow"
xmlns:vm="clr-namespace:noteManager.ViewModel"
DataContext="{StaticResource noteManagerViewModel}"
Title="NoteManager" Height="490" Width="525">
<Grid Margin="0,0,0,-132.5">
<DataGrid Name="dataGrid1" Grid.Row="2" Margin="8,7,-22,7" AutoGenerateColumns="False"
ItemsSource="{Binding NoteGrid, Mode=TwoWay}" SelectedItem="{Binding Path=MySelectedNote}" HorizontalAlignment="Center"
Width="480" Grid.ColumnSpan="6" Grid.Column="1">
<DataGrid.Columns>
<DataGridTextColumn Width="100" Binding="{Binding Path=NoteText, Mode=TwoWay}" Header="Titre" />
<DataGridTextColumn Width="200" Binding="{Binding Path=ContentText, Mode=TwoWay}" Header="Note" />
<DataGridTextColumn Width="100" Binding="{Binding Path=CreatedAt, Mode=TwoWay}" Header="Date de création" />
<DataGridTextColumn Width="100" Binding="{Binding Path=UpdatedAt, Mode=TwoWay}" Header="Dat MAJ" />
</DataGrid.Columns>
</DataGrid>
</Grid>
</Window>
（仅重要部分）
这是我的视图模型和类：
class DataRepository : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
void Notify(string property)
{
if (this.PropertyChanged != null)
{
this.PropertyChanged(this, new PropertyChangedEventArgs(property));
}
}
public IEnumerable<Note> GetNotes()
{
var __list = new List<Note>();
__list.Add(new Note() { NoteText = "a", ContentText = "super texte de malade", CreatedAt = "super texte de malade", UpdatedAt = "super texte de malade", UserId = 2 });
__list.Add(new Note() { NoteText = "b", ContentText = "super texte de malade", CreatedAt = "super texte de malade", UpdatedAt = "super texte de malade", UserId = 2 });
__list.Add(new Note() { NoteText = "c", ContentText = "super texte de malade", CreatedAt = "super texte de malade", UpdatedAt = "super texte de malade", UserId = 2 });
__list.Add(new Note() { NoteText = "d", ContentText = "super texte de malade", CreatedAt = "super texte de malade", UpdatedAt = "super texte de malade", UserId = 2 });
__list.Add(new Note() { NoteText = "e", ContentText = "super texte de malade", CreatedAt = "super texte de malade", UpdatedAt = "super texte de malade", UserId = 2 });
__list.Add(new Note() { NoteText = "f", ContentText = "super texte de malade", CreatedAt = "super texte de malade", UpdatedAt = "super texte de malade", UserId = 2 });
return __list;
}
}
public class Note : INotifyPropertyChanged
{
public int Id { get; set; }
public string NoteText { get; set; }
public string ContentText { get; set; }
public string CreatedAt { get; set; }
public string UpdatedAt { get; set; }
public int UserId { get; set; }
//public virtual User User { get; set; }
public event PropertyChangedEventHandler PropertyChanged;
public void Notify(string property)
{
if (this.PropertyChanged != null)
{
this.PropertyChanged(this, new PropertyChangedEventArgs(property));
}
}
}
public class noteManagerViewModel : INotifyPropertyChanged
{
int currentUser;
string login;
public string Login
{
get
{
return login;
}
set
{
login = value; Notify("Login");
}
}
string titre;
public string Titre
{
get
{
return titre;
}
set
{
titre = value; Notify("Titre");
}
}
string note;
public string Note
{
get
{
return note;
}
set
{
note = value; Notify("Note");
}
}
private bool _canExecute;
private ICommand _testConnexion;
public ICommand testConnexion
{
get
{
return _testConnexion ?? (_testConnexion = new CommandHandler(() => Connexion(), _canExecute));
}
}
private ICommand _addNote;
public ICommand addNote
{
get
{
return _addNote ?? (_addNote = new CommandHandler(() => ajouterNote(), _canExecute));
}
}
private ICommand _addUser;
public ICommand addUser
{
get
{
return _addUser ?? (_addUser = new CommandHandler(() => AjoutUser(), _canExecute));
}
}
public IEnumerable<Note> NoteGrid { get; private set; }
public noteManagerViewModel()
{
_canExecute = true;
currentUser = 0;
var __listNote = new DataRepository();
NoteGrid = __listNote.GetNotes();
}
public event PropertyChangedEventHandler PropertyChanged;
void Notify(string property)
{
if (this.PropertyChanged != null)
{
this.PropertyChanged(this, new PropertyChangedEventArgs(property));
}
}
/// public ObservableCollection<Note> DataGridNotes { get; set; }
void Connexion()
{
string cs = @"server=localhost;userid=root;
password=root;database=notemanager";
MySqlConnection conn = null;
MySqlDataReader rdr = null;
try
{
conn = new MySqlConnection(cs);
conn.Open();
string stm = "SELECT * FROM user";
MySqlCommand cmd = new MySqlCommand(stm, conn);
rdr = cmd.ExecuteReader();
if (!utilisateurExistant())
{
MessageBox.Show("L'utilisateur n'existe pas");
}
else
{
while (rdr.Read())
{
if (rdr.GetString(1) == login)
{
currentUser = int.Parse(rdr.GetString(0));
afficherNotes(currentUser);
}
}
}
//sa récup toutes les notes c'est génial
//MessageBox.Show("c'est gagné");
}
catch (MySql.Data.MySqlClient.MySqlException ex)
{
MessageBox.Show(ex.Message);
}
finally
{
if (rdr != null)
{
rdr.Close();
}
if (conn != null)
{
conn.Close();
}
}
}
和视图模型的构造函数：
public noteManagerViewModel()
{
_canExecute = true;
currentUser = 0;
var __listNote = new DataRepository();
NoteGrid = __listNote.GetNotes();
}
使用此方法时，我的数据网格显示得很好，但是当我尝试在按下按钮而不是在构造函数中显示数据时，不会显示任何数据。
提前感谢。
按下按钮时，您可以执行以下两项操作之一：
- 创建一个新列表，在这种情况下，您需要确保
NoteGrid在其 setter 中引发PropertyChanged - 添加到现有列表，该列表不会使用
List传播到 UI。要传播这些更改，您需要一个实现INotifyCollectionChanged的集合。ObservableCollection<T>是一个不错的选择，所以我会使用它而不是List用于NoteGrid属性。
让我们试试
private IEnumerable<Note> _noteGrid
public IEnumerable<Note> NoteGrid
{
get { return _noteGrid; }
private set { _noteGrid = value; Notify("NoteGrid "); }
}
将网格绑定到 NoteGrid 属性，但不支持 INotifyPropertyChanged 。
如果使用 List，则需要通知要在数据网格中显示的每个属性的 UI 。
private string _notetext;
public string NoteText
{
get
{
return _notetext;
}
set
{
if(_notetext!=value)
{
_notetext=value;
Notify("NoteText");
}
}
}