使用MVVM、实体框架和mysql将基本数据绑定到textbox

让我们从INotifyPropertyChanged接口开始,并介绍如何实现它。一般来说,我试图创建一个抽象类,Model和ViewModel都使用这个抽象类,它包含了我的所有模型和viewmodels中常见的一切。以下是这些抽象类:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.ComponentModel;
using System.Runtime.CompilerServices;

namespace WpfStackOverflow.Models
{
/// <summary>
/// Abstract class that provides common functionality accross all View Models.
/// </summary>
public abstract class modelBase : INotifyPropertyChanged
{

    #region INotifyPropertyChanged
    /// <summary>
    /// Provides a simplefied INotifyPropertyChanged interface.
    /// requires System.Runtime.CompilerServices and
    /// System.ComponentModel.
    /// </summary>
    /// <param name="property"></param>
    public void SetPropertyChanged([CallerMemberName] string property = null)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(property));
    }

    public event PropertyChangedEventHandler PropertyChanged;
}
#endregion
}

namespace WpfStackOverflow.ViewModels
{
    /// <summary>
    /// Abstract class that provides common functionality accross all View     Models.
    /// </summary>
    public abstract class ViewModelBase : INotifyPropertyChanged
    {

        #region INotifyPropertyChanged
        /// <summary>
        /// Provides a simplefied INotifyPropertyChanged interface.
        /// requires System.Runtime.CompilerServices and
        /// System.ComponentModel.
        /// </summary>
        /// <param name="property"></param>
        public void SetPropertyChanged([CallerMemberName] string property = null)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(property));
        }

        public event PropertyChangedEventHandler PropertyChanged;
        #endregion
    }
}

以下是我创建的视图模型:

namespace WpfStackOverflow.ViewModels
{
    class BasicMVVMViewModel:ViewModelBase
    {

        private ObservableCollectionEx<LocationKPI> _locations;

        public BasicMVVMViewModel()
        {
            CreateTestData();
        }

        private DateTime _selectedDate;
        public DateTime SelectedDate
        {

            get { return _selectedDate; }
            set
            {
                _selectedDate = value;
                SetPropertyChanged();
                SetSelectedLocationKPI( _selectedDate.Month);
            }
        }

        private LocationKPI _selectedLocationKPI;
        public LocationKPI SelectedLocationKPI
        {
            get { return _selectedLocationKPI; }
            set
            {
                _selectedLocationKPI = value;
                SetPropertyChanged();
            }
        }

        private void  SetSelectedLocationKPI(long sMonth)
        {
            SelectedLocationKPI = _locations.Where(p => p.SMonth.Equals(sMonth)).FirstOrDefault();
        }


        private void CreateTestData()
        {

            _locations = new ObservableCollectionEx<LocationKPI>();
            for(int i=0; i < 12;i++)
            {
                _locations.Add(new LocationKPI() { SMonth = i, Efficiency = i*17 });
            }

        }

    }
}

<UserControl x:Class="WpfStackOverflow.Controls.BasicMVVM"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:WpfStackOverflow.Controls"
             mc:Ignorable="d" 
             d:DesignHeight="300" d:DesignWidth="300">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="35"/>
            <RowDefinition Height="35"/>
            <RowDefinition Height="35"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <DatePicker HorizontalAlignment="Left" Margin="30,5,0,0"   Grid.Row="1" VerticalAlignment="Top" Width="150" SelectedDate="{Binding SelectedDate}"/>
        <TextBlock x:Name="textBlock" HorizontalAlignment="Stretch"  Grid.Row="2" TextWrapping="Wrap" 
               Text="{Binding SelectedLocationKPI.Efficiency,Mode=TwoWay}" VerticalAlignment="Stretch" Margin="5"/>

    </Grid>
</UserControl>

在Viewmodel中,我调用了一个创建测试数据的方法。在您的情况下,您可以从linq查询中获取数据。(你弄明白了:)

您必须调整一些引用和命名以适应您的环境。我在这里发布的内容经过了测试,效果良好。我希望它能帮助您更好地理解MVVM。哦,是的,还有一件事,你在这里看到的XAML来自用户控件,而不是XAML窗口。在代码隐藏中,您必须实例化ViewModel并将其设置为DataContext:

namespace WpfStackOverflow.Controls
{
    /// <summary>
    /// Interaction logic for BasicMVVM.xaml
    /// </summary>
    public partial class BasicMVVM : UserControl
    {
        public BasicMVVM()
        {
           InitializeComponent();
           DataContext = new BasicMVVMViewModel();
        }
    }
}