将 MVVM class 链接到 XAML

Question

我有下面的 ViewModel Class，我在 XAML..

中用作 DataContext

 public class ViewModel
    {
        public ObservableCollection<Model> Collection { get; set; }
        public ViewModel()
        {
            Collection = new ObservableCollection<Model>();
            GenerateDatas();
        }
        private void GenerateDatas()
        {
            this.Collection.Add(new Model(0, 1));
            this.Collection.Add(new Model(1, 2));
            this.Collection.Add(new Model(2, 3));
            this.Collection.Add(new Model(3, 4));
        }
    }
    public class Model
    {
        public double X { get; set; }
        public double Y { get; set; }

        public Model(double x, double y)
        {
            X = x;
            Y = y;
        }
    }

i link 通过在 XAML 中创建应用程序的命名空间，如下所示：

xmlns:local="clr-namespace:MyApplication"

然后我按如下方式访问 ViewModel 作为 DataContext：

     <sparrow:SparrowChart.DataContext>
           <local:ViewModel/>
     </sparrow:SparrowChart.DataContext>

但我收到一个错误消息，指出名称 ViewModel 在本地命名空间中不存在。我该如何解决这个问题？

完整的 XAML 文件：

<phone:PhoneApplicationPage
x:Class="SparrowCharts.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:phone="clrnamespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:sparrow="clr-namespace:Sparrow.Chart;assembly=Sparrow.Chart.WP8.45"
xmlns:local="clr-namespace:MyApplication"

mc:Ignorable="d"
FontFamily="{StaticResource PhoneFontFamilyNormal}"
FontSize="{StaticResource PhoneFontSizeNormal}"
Foreground="{StaticResource PhoneForegroundBrush}"
SupportedOrientations="Portrait" Orientation="Portrait"
shell:SystemTray.IsVisible="True">

<!--LayoutRoot is the root grid where all page content is placed-->
<Grid x:Name="LayoutRoot" Background="Transparent">
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>



    <!--TitlePanel contains the name of the application and page title-->
    <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
        <TextBlock Text="MY APPLICATION" Style="{StaticResource PhoneTextNormalStyle}" Margin="12,0"/>
        <TextBlock Text="page name" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
    </StackPanel>

    <!--ContentPanel - place additional content here-->
    <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
        <sparrow:SparrowChart>
            <sparrow:SparrowChart.DataContext>
                <local:ViewModel/>
            </sparrow:SparrowChart.DataContext>
            <sparrow:SparrowChart.XAxis>
                <sparrow:LinearXAxis/>
            </sparrow:SparrowChart.XAxis>
            <sparrow:SparrowChart.YAxis>
                <sparrow:LinearYAxis/>
            </sparrow:SparrowChart.YAxis>
            <sparrow:LineSeries PointsSource="{Binding Collection}" XPath="X" YPath="Y"/>
        </sparrow:SparrowChart>
    </Grid>
</Grid>

C#代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Navigation;
using Microsoft.Phone.Controls;
using Microsoft.Phone.Shell;
using MyApplication.Resources;
using System.Collections.ObjectModel;

namespace MyApplication
{
public partial class MainPage : PhoneApplicationPage
{
    // Constructor
    public MainPage()
    {
        InitializeComponent();

        // Sample code to localize the ApplicationBar
        //BuildLocalizedApplicationBar();
    }


    // Create a ViewModel
    public class ViewModel
    {
        public ObservableCollection<Model> Collection { get; set; }
        public ViewModel()
        {
            Collection = new ObservableCollection<Model>();
            GenerateDatas();
        }
        private void GenerateDatas()
        {
            this.Collection.Add(new Model(0, 1));
            this.Collection.Add(new Model(1, 2));
            this.Collection.Add(new Model(2, 3));
            this.Collection.Add(new Model(3, 4));
        }
    }
    public class Model
    {
        public double X { get; set; }
        public double Y { get; set; }

        public Model(double x, double y)
        {
            X = x;
            Y = y;
        }
    }

}
}

Answer 1

试试这个代码：

<phone:PhoneApplicationPage
x:Class="SparrowCharts.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:phone="clrnamespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:sparrow="clr-namespace:Sparrow.Chart;assembly=Sparrow.Chart.WP8.45"
xmlns:local="clr-namespace:MyApplication"

mc:Ignorable="d"
FontFamily="{StaticResource PhoneFontFamilyNormal}"
FontSize="{StaticResource PhoneFontSizeNormal}"
Foreground="{StaticResource PhoneForegroundBrush}"
SupportedOrientations="Portrait" Orientation="Portrait"
shell:SystemTray.IsVisible="True">

<phone:PhoneApplicationPage.DataContext>
    <local:ViewModel />
</phone:PhoneApplicationPage.DataContext>

<!--LayoutRoot is the root grid where all page content is placed-->
<Grid x:Name="LayoutRoot" Background="Transparent">
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>



    <!--TitlePanel contains the name of the application and page title-->
    <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
        <TextBlock Text="MY APPLICATION" Style="{StaticResource PhoneTextNormalStyle}" Margin="12,0"/>
        <TextBlock Text="page name" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
    </StackPanel>

    <!--ContentPanel - place additional content here-->
    <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
        <sparrow:SparrowChart>
            <sparrow:SparrowChart.XAxis>
                <sparrow:LinearXAxis/>
            </sparrow:SparrowChart.XAxis>
            <sparrow:SparrowChart.YAxis>
                <sparrow:LinearYAxis/>
            </sparrow:SparrowChart.YAxis>
            <sparrow:LineSeries PointsSource="{Binding DataContext.Collection, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type phone:PhoneApplicationPage}}}" XPath="X" YPath="Y"/>
        </sparrow:SparrowChart>
    </Grid>
</Grid>

Answer 2

如果您确定视图模型驻留在正确的命名空间中，请尝试以下声明：

xmlns:local="clr-namespace:MyApplication;assembly="

Answer 3

ViewModel 嵌套在 Window 中。所以它的全称是MyApplication.MainWindow.ViewModel

拉出来放到自己的文件和正确的命名空间中。

顺便说一下：确保 ViewModel class 实现了 INotifyPropertyChanged

Answer 4

检查你的花括号，ViewModel class 应该只包含在命名空间花括号中而不是 MainPage 花括号 brace.Then 你可以创建一个新的Model class 的文件或将其单独放在 MainPage 下方。

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