在列表视图中设置默认组合框值

Question

我在列表视图中有一个网络视图和一个组合框，其数据是从服务器获取的。 我希望组合框的默认值与下面的字符串匹配：

string A = "A:C:B:D:E";

XAML：

<ListView
    Name="ListPairOption"
    Height="auto">
    <ListView.ItemTemplate>
        <DataTemplate x:DataType="data:PairClass">
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*"/>
                    <ColumnDefinition Width="auto"/>
                </Grid.ColumnDefinitions>

                <Grid
                    x:Name="pilganStack"
                    Grid.Column="0"
                    Margin="10,10,10,10"
                    HorizontalAlignment="Stretch"
                    Background="#FFDFF6EE">
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="*"/>
                    </Grid.ColumnDefinitions>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="*"/>
                    </Grid.RowDefinitions>
                    <WebView
                        x:Name="option"
                        Margin="5,5,5,5"
                        MinHeight="60"
                        Height="auto"
                        HorizontalAlignment="Stretch"
                        local:MyProperties.HtmlString="{Binding Name}"
                        DefaultBackgroundColor="Transparent"/>
                    <TextBlock
                        x:Name="index"
                        FontSize="20"
                        Text="{Binding Ind}" 
                        Visibility="Collapsed"/>
                </Grid>
                <ComboBox
                    x:Name="pairOption"
                    Grid.Column="1"
                    Margin="10,10,10,0"
                    DisplayMemberPath="NameA"
                    SelectedValuePath="Pilgan"
                    ItemsSource="{Binding DataContext.PilihanS, ElementName=ListPairOption}"
                    Background="#FFDFF6EE"
                    FontSize="17"
                    FontWeight="SemiBold"
                    PlaceholderText="Pilih"
                    Foreground="Black"
                    PlaceholderForeground="Black"
                    CornerRadius="10,10,10,10" 
                    SelectionChanged="pairOption_SelectionChanged" 
                    BorderBrush="#FF79D9BD" 
                    BorderThickness="1"/>
            </Grid>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

代码：

private List<MyClass> _items;
string urlPath = "https://";
 var httpClient = new HttpClient(new HttpClientHandler());
 var response = await httpClient.GetAsync(urlPath);
string jsonText = await response.Content.ReadAsStringAsync();
 JsonObject jsonObject = JsonObject.Parse(jsonText);
double id = jsonObject["EXAM_ASM_A_ID"].GetNumber();
string questionID = jsonObject["EXAM_QUESTION_ID"].GetString();
string choiceA = questionObject.ContainsKey("choice_a") && questionObject["choice_a"] != null ? questionObject["choice_a"].GetString() : string.Empty;
string choiceB = questionObject.ContainsKey("choice_b") && questionObject["choice_b"] != null ? questionObject["choice_b"].GetString() : string.Empty;
string choiceC = questionObject.ContainsKey("choice_c") && questionObject["choice_c"] != null ? questionObject["choice_c"].GetString() : string.Empty;
string choiceD = questionObject.ContainsKey("choice_d") && questionObject["choice_d"] != null ? questionObject["choice_d"].GetString() : string.Empty;
string choiceE = questionObject.ContainsKey("choice_e") && questionObject["choice_e"] != null ? questionObject["choice_e"].GetString() : string.Empty;
_items = new List<MyClass>();
_items.Add(new MyClass() { Name = choiceA });
_items.Add(new MyClass() { Name = choiceB });
_items.Add(new MyClass() { Name = choiceC });
_items.Add(new MyClass() { Name = choiceD });
_items.Add(new MyClass() { Name = choiceE });
 string c = "";
 string v1 = "";
 JsonArray mapArray = questionObject["map"].GetArray();
 foreach (JsonValue mapValue in mapArray)
 {
     JsonArray mapArrayI = mapValue.GetArray();
     PairClass pair = new PairClass();
     foreach (JsonValue mapValueI in mapArrayI)
     {
         string choice = "";
         try
         {
             if (mapValueI.ToString().All(char.IsDigit))
             {
                 c = String.Concat(mapValueI.ToString().Where(Char.IsDigit));
                 index = Int16.Parse(c);
                 pair.Ind = index;
             }
             else
             {
                 string v = mapValueI.ToString();
                 var collection = Regex.Matches(v, "\\\"(.*?)\\\"");
                 foreach (var item in collection)
                 {
                     v1 = item.ToString().Trim('"');
                     choice = v1;
                     pair.Name = choice;
                 }
             }
         }
         catch
         {
         }
     }
     itemL.Add(pair);
 }
 JsonArray pairArray = questionObject["pairs"].GetArray();
 foreach (JsonValue pairValue in pairArray)
 {
     string pairKey = "";
     string pairString = "";
     JsonArray pairArrayI = pairValue.GetArray();
     foreach (JsonValue pairValueI in pairArrayI)
     {
         try
         {
             string v = pairValueI.ToString();
             if (Regex.IsMatch(v, @"\b[A-E]\b"))
             {
                 var collection = Regex.Matches(v, "\\\"(.*?)\\\"");
                 foreach (var item in collection)
                 {
                     string v2 = item.ToString().Trim('"');
                     pairKey = v2;
                 }
             }
             else
             {
                 var collection = Regex.Matches(v, "\\\"(.*?)\\\"");
                 foreach (var item in collection)
                 {
                     string v3 = item.ToString().Trim('"');
                     pairString = v3;
                     //Debug.WriteLine("pair string: " + pairString);
                     if(pairString.Contains("&amp;"))
                     {
                         pairString = pairString.Replace("&amp;", " & ");
                     }
                 }
             }
         }
         catch
         {
         }
     }
     PilihanS.Add(new ComboBoxClass() { Pilgan = pairKey, NameA = pairString });
 }
 ListPairOption.Visibility = Visibility.Visible;
 var list = itemL.OrderBy(p => p.Ind).ToList();
 ListPairOption.ItemsSource = list;

    public class MyClass
    {
        public string Name { get; set; }
        public override string ToString()
        {
            return this.Name;
        }
    }

PairClass.cs

public class PairClass
{
    public int Ind { get; set; }
    public string Name { get; set; }
    public ObservableCollection<ComboBoxClass> PilihanS { get; set; }

    public PairClass()
    {
        Ind = int.MinValue;
        Name = string.Empty;
        PilihanS = new ObservableCollection<ComboBoxClass>();
    }

    public PairClass(int ind, string name, string pilihan)
    {
        Ind = ind;
        Name = name;
    }
}

public class ComboBoxClass
{
    public string Pilgan { get; set; }
    public string NameA { get; set; }

    public override string ToString()
    {
        return this.NameA;
    }
}

如何设置列表视图中组合框的默认值？

注：

• 如果来自上面的字符串，则列表视图有 5 个索引
• 字符串中的第一个字符是列表视图中第一个索引处第一个选择的组合框值
• 字符串中的第三个字符是列表视图中第二个索引处的第三个选项的组合框值
• 字符串中的第 5 个字符是列表视图中第三个索引处的第二个选项的组合框值
• 字符串中的第 7 个字符是列表视图中第 4 个索引处的第四个选项的组合框值
• 字符串中的第 9 个字符是列表视图中第 5 个索引处的第 5 个选项的组合框值 欲了解更多详情，请参见下图：

Answer 1

设置默认组合框值

如果您想设置默认的组合框值，您可以尝试将

SelectedIndex 

属性绑定到数据上下文的值。当您设置

SelectedIndex

时，组合框将显示源索引处的值。

在您的场景中，

PairClass

是

ComboBox

的数据上下文，因此您可以在

PairClass

中创建一个新属性，并使用它绑定到ComboBox的

SelectedIndex

属性。