如何使用 MVVM 同时绑定 Progressbar 和 Datagrid? [英] How to bind Progressbar and Datagrid at the same time using MVVM?

问题描述

我正在尝试使用 MVVM 构建进度条.基本上，我有一个主要的 xaml 和 2 个用户控件，1 个用于数据网格的进度条 1.我有点新，我关注了这个问答，但我没有得到任何成功.下面是我的 ViewModel 代码和 Xaml 代码.基本上我有两个问题，

I am trying to build a progressbar using MVVM. Basically, I have a main xaml and 2 UserControls, 1 for progressbar 1 for datagrid. I am bit new and I followed this question and answer but I havent got any success. Below is my ViewModel code and Xaml code. Basically I have 2 problems,

1-如何绑定 CustomerModels 或者甚至可能的话 CustomerViewModel?我尝试将 Itemsource 绑定直接与 ObservableCollection 一起使用，我正在用我的 delegateCommand 填充它，该委托命令与后台工作人员一起运行，但没有成功.我试过没有委托和后台工作人员，简单地使用如下.

1-How to bind CustomerModels or if even possible CustomerViewModel? I tried to use Itemsource binding direcly with ObservableCollection which I am filling with my delegateCommand that runs with a backgroundworker but no success. I tried without delegate and backgroundworker,simply using as below.

Me.myLoadCommand = New Commands.LoadCustomerModels()

Me.myLoadCommand = New Commands.LoadCustomerModels()

我做错了什么?

<UserControl.Resources>    
        <vm:CustomerModelsVM x:Key="Customerobj"></vm:CustomerModelsVM>
    </UserControl.Resources>
<Grid >
 <DataGrid x:Name="grdData"  ItemsSource="{Binding Path=CustomerModels}"/>
</Grid>

2-如何绑定CurrentProgressBar?我试图以同样的方式绑定进度条状态，但我相信我的 ViewModel 和 Xaml 不知何故没有联系.

2-How to bind CurrentProgressBar? I tried to bind the progress bar status same way but I believe my ViewModel and Xaml somehow has no connection.

<UserControl x:Class="ucProgressBar"
         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" 
         mc:Ignorable="d" 
                    >
<Grid>
    <ProgressBar Value="{Binding CurrentProgress, Mode=OneWay}"  Visibility="{Binding ProgressVisibility}"></ProgressBar>
    <TextBlock Text="{Binding ElementName=myProgressBar, Path=Value, StringFormat={}{0:0}%}" HorizontalAlignment="Center" VerticalAlignment="Center" />
</Grid>

命名空间视图模型

Public Class CustomerModelsVM
    Implements ICustomerModelsVM
    Implements INotifyPropertyChanged

    Public Event PropertyChanged As PropertyChangedEventHandler _
     Implements INotifyPropertyChanged.PropertyChanged

    Private ReadOnly worker As BackgroundWorker
    Private m_currentProgress As Integer
    Private _CustomerModels As New ObservableCollection(Of Models.CustomerModel)
    Private mySaveCommand As ICommand
    Private myLoadCommand As ICommand

    Public Sub New()
        Me.worker = New BackgroundWorker()
        Me.myLoadCommand = New DelegateCommand(Sub() Me.worker.RunWorkerAsync(), AddressOf Progressisbusy)
       ' _CustomerModels = getCustomerModels()
        Me.worker = New BackgroundWorker()
        AddHandler Me.worker.DoWork, AddressOf Me.DoWork
        AddHandler Me.worker.ProgressChanged, AddressOf Me.ProgressChanged

    End Sub

    Private Sub ProgressChanged(sender As Object, e As ProgressChangedEventArgs)
        Me.CurrentProgress = e.ProgressPercentage
    End Sub

    Private Function Progressisbusy() As Boolean
        Return Not Me.worker.IsBusy
    End Function

    Private Sub OnPropertyChanged(Optional ByVal propertyName As String = Nothing)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
    End Sub

    Public ReadOnly Property CustomerModels() As ObservableCollection(Of Models.CustomerModel)
        Get
            Return _CustomerModels
        End Get
    End Property

    Public ReadOnly Property btnClick() As ICommand
        Get
            Return myLoadCommand
        End Get
    End Property

    Public Property CurrentProgress() As Integer
        Get
            Return Me.m_currentProgress
        End Get
        Private Set(value As Integer)
            If Me.m_currentProgress <> value Then
                Me.m_currentProgress = value
                OnPropertyChanged(Me.CurrentProgress)
            End If
        End Set
    End Property

    Private Sub DoWork(sender As Object, e As DoWorkEventArgs)
            _CustomerModels = getCustomerModels()
    End Sub


    Function getCustomerModels() As ObservableCollection(Of Models.CustomerModel) Implements ICustomerModelsVM.GetCustomerModels

        If _CustomerModels Is Nothing OrElse _CustomerModels.Count = 0 Then myLoadCommand.Execute(_CustomerModels)

        Return _CustomerModels
    End Function

推荐答案

我想用一个可行的解决方案来回答我的问题.就我而言，问题很简单，我必须使用调度程序来清除我的可观察集合.所以我的 Do_work 函数如下所示.在开始绑定之前，我没有清除可观察集合.添加这个简单的行使我的代码工作.

I would like answer my question with a working solution. In my case problem was simply, I had to use dispatcher to clear my oberservable collection. So my Do_work function looks like as following. I didnt clear the observable collection before I start binding. Adding this simple line makes my code working.

    Private Sub DoWork(sender As Object, e As DoWorkEventArgs)
        Application.Current.Dispatcher.BeginInvoke(Sub() Me.CustomerModels.Clear())

        ' Me.CustomerModels.Clear()
        For index = 1 To 100

            Dim CustomerModel As New CustomerModel With { _
                .age = 30 + index, _
                .name = "testName" & index, _
                .surname = "testSurname" & index, _
                .Id = index}

            Application.Current.Dispatcher.BeginInvoke(Sub() CustomerModels.Add(CustomerModel))
            '  CustomerModels.Add(CustomerModel)
            Thread.Sleep(100)
            worker.ReportProgress(CalculateProgress(100, index))
        Next


    End Sub

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