我试图获得一个以neo4j作为数据源运行的Autocomplete TextBox,为此,我需要将所有已创建的元素作为List返回,在其中我可以在其中“搜索”。
我有一个列表,我有一个查询neo4j DB的连接以获取所有人的名字,如果我们收到数据,则显示一个MessageBox只是为了测试,但是如果我在文本框中输入字母,则我的应用程序将冻结。
后面的代码:
public partial class UserControlQueryDB : UserControl
{
public UserControlQueryDB()
{
InitializeComponent();
GetSuggestionsFromNeoAsync();
}
private async Task<List<string>> GetSuggestionsFromNeoAsync() {
IDriver driver = GraphDatabase.Driver("bolt://localhost:7687", AuthTokens.Basic("neo4j", "neo4j"));
IAsyncSession session = driver.AsyncSession(o => o.WithDatabase("neo4j"));
var query2Neo = "MATCH (n:Person) RETURN n.Name";
IResultCursor cursor = await session.RunAsync(query2Neo);
List<string> found = await cursor.ToListAsync(record => record["name"].As<string>());
await cursor.ConsumeAsync();
await session.CloseAsync();
await driver.CloseAsync();
return found;
}
private void TextBox_KeyUp(object sender, KeyEventArgs e)
{
bool found = false;
var border = (resultStack.Parent as ScrollViewer).Parent as Border;
var data = GetSuggestionsFromNeoAsync();
MessageBox.Show(data);
string query = (sender as TextBox).Text;
if (query.Length == 0)
{
// Clear
resultStack.Children.Clear();
border.Visibility = Visibility.Collapsed;
}
else
{
border.Visibility = Visibility.Visible;
}
// Clear the list
resultStack.Children.Clear();
// Add the result
foreach (var obj in data.Result)
{
if (obj.ToLower().StartsWith(query.ToLower()))
{
// The word starts with this... Autocomplete must work
addItem(obj);
found = true;
}
}
if (!found)
{
resultStack.Children.Add(new TextBlock() { Text = "No results found." });
}
}
private void addItem(string text)
{
TextBlock block = new TextBlock();
// Add the text
block.Text = text;
// A little style...
block.Margin = new Thickness(2, 3, 2, 3);
block.Cursor = Cursors.Hand;
// Mouse events
block.MouseLeftButtonUp += (sender, e) =>
{
textBox.Text = (sender as TextBlock).Text;
};
block.MouseEnter += (sender, e) =>
{
TextBlock b = sender as TextBlock;
b.Background = Brushes.PeachPuff;
};
block.MouseLeave += (sender, e) =>
{
TextBlock b = sender as TextBlock;
b.Background = Brushes.Transparent;
};
}
}
那是Xaml:
<StackPanel Orientation="Horizontal">
<TextBox Width="300" Padding="5, 3, 5, 3" KeyUp="TextBox_KeyUp" Name="textBox" />
<Border Width="298" Height="150" BorderBrush="Black" BorderThickness="1">
<ScrollViewer VerticalScrollBarVisibility="Auto">
<StackPanel Name="resultStack"></StackPanel>
</ScrollViewer>
</Border>
</StackPanel>
请不要忘记在事件处理程序中将await
方法设置为async
(并在事件处理程序的签名中添加async
关键字):
private async void TextBox_KeyUp(object sender, KeyEventArgs e)
{
bool found = false;
var border = (resultStack.Parent as ScrollViewer).Parent as Border;
var data = await GetSuggestionsFromNeoAsync(); //<--
...