在哪里通过代码设置验证错误？

Question

有人告诉我，Christian Moser (http://wpftutorial.net/ValidationErrorByCode.html) 的这段代码在只有源发生变化时用于验证，但我不知道该放在哪里。我试图放入一个 'PreviewLostKeyboardFocus' 类，但它不起作用。我已经有一个验证类，它仅在文本框中有直接用户输入时才起作用，但我也希望通过其他文本框的计算进行验证。

我在 ViewModel 中也有属性：INotifyPropertyChanged，但我是 MVVM 的新手。所以我对 IDataErrorInfo 不熟悉，如果可能的话，我宁愿使用 INotifyPropertyChanged。

ValidationError validationError = 
    new ValidationError(regexValidationRule, 
    textBox.GetBindingExpression(TextBox.TextProperty));

validationError.ErrorContent = "This is not a valid e-mail address";

Validation.MarkInvalid(
    textBox.GetBindingExpression(TextBox.TextProperty), 
    validationError);

我的财产

private int _FIMSamlet_score;
        public int FIMSamlet_score
        {
            get { return this._FIMSamlet_score; }
            set
            {
                if (Int32.Parse(value.ToString()) < 18 || Int32.Parse(value.ToString()) > 126)
                { throw new ArgumentException("The value must be between 18 and 126"); }
                this._FIMSamlet_score = value;
                this.OnPropertyChanged("FIMSamlet_score");
            }
        }

Answer 1

IDataErrorInfo 是使用INotifyPropertyChanged 的验证方案的一部分。当您在 Binding 上设置 ValidateOnDataErrors=true 时，在获取 INotifyPropertyChanged 启用的属性期间，将验证值并设置值。

您所链接的方法需要您将大量业务逻辑放在代码隐藏中，这违反了 MVVM 的职责分离原则（哑视图、智能视图模型）。

我强烈建议您了解IDataErrorInfo，更重要的是了解System.ComponentModel.DataAnnotations 定义的ValidationAttributes，因为它们实际上是在纯MVVM 环境中执行验证的最简单方法。

看看这个来自 Microsoft 的代码示例，它向您展示了如何将这些注释与 IDataErrorInfo 集成到一个基础 ViewModel 类中，您可以从该类继承并用作通用基础验证 ViewModel 类：@987654321 @

Answer 2

        ViewModel -> VMStudent.cs

        using GalaSoft.MvvmLight;
        using GalaSoft.MvvmLight.Command;
        using System;
        using System.Collections.Generic;
        using System.Collections.ObjectModel;
        using System.ComponentModel;
        using System.Linq;
        using System.Text;
        using System.Text.RegularExpressions;
        using System.Threading.Tasks;
        using System.Windows;
        using WpfDesktopCrud.Model;

        namespace WpfDesktopCrud.ViewModel
        {
            class VMStudent : ViewModelBase, IDataErrorInfo
            {
                public VMStudent()
                {
                    try
                    {

                        Students = new ObservableCollection<Student>();
                        Students.Add(new Student { id = 1, name = "Dhru", mobno = "0000000000", address = "Shahibaug", email = "dhrusoni84@gmail.com" });
                        Students.Add(new Student { id = 2, name = "Soni", mobno = "9033259059", address = "Vastrapur", email = "dhru_soni@yahoo.com" });
                        SaveCommand = new RelayCommand(Save);
                        NewCommand = new RelayCommand(New);
                        DeleteCommand = new RelayCommand(Delete);
                        PropertyChanged += VMStudent_PropertyChanged;
                    }
                    catch (Exception ex)
                    {
                        throw;
                    }
                }

                void VMStudent_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
                {
                    switch (e.PropertyName)
                    {
                        case "Selected":
                            if (Selected != null)
                            {
                                ID = Selected.id;
                                Name = Selected.name;
                                MobileNo = Selected.mobno;
                                Address = Selected.address;
                                Email = Selected.email;

                            }
                            break;
                    }
                }

                #region Properties

                private ObservableCollection<Student> _Students;

                public ObservableCollection<Student> Students
                {
                    get { return _Students; }
                    set
                    {
                        _Students = value;
                        RaisePropertyChanged("Students");
                    }
                }

                private Student _Selected;

                public Student Selected
                {
                    get { return _Selected; }
                    set
                    {
                        _Selected = value;
                        RaisePropertyChanged("Selected");
                    }
                }

                private int _ID;

                public int ID
                {
                    get { return _ID; }
                    set
                    {
                        _ID = value;
                        RaisePropertyChanged("ID");
                    }
                }

                private string _Name;

                public string Name
                {
                    get { return _Name; }
                    set
                    {
                        _Name = value;
                        RaisePropertyChanged("Name");
                    }
                }

                private string _MobileNo;

                public string MobileNo
                {
                    get { return _MobileNo; }
                    set
                    {
                        _MobileNo = value;
                        RaisePropertyChanged("MobileNo");
                    }
                }
                private string _Address;

                public string Address
                {
                    get { return _Address; }
                    set
                    {
                        _Address = value;
                        RaisePropertyChanged("Address");
                    }
                }
                private string _Email;

                public string Email
                {
                    get { return _Email; }
                    set
                    {
                        _Email = value;
                        RaisePropertyChanged("Email");
                    }
                }


                #endregion

                #region Commands

                public RelayCommand SaveCommand { get; set; }

                public RelayCommand NewCommand { get; set; }

                public RelayCommand DeleteCommand { get; set; }

                #endregion

                #region Methods
                public void Save()
                {
                    if (Selected != null)
                    {
                        if (Selected.id != 0)
                        {
                            Selected.name = this.Name;
                            Selected.mobno = this.MobileNo;
                            Selected.address = this.Address;
                            Selected.email = this.Email;
                            MessageBox.Show("Record Updated.", "WPF MVVM", MessageBoxButton.OK, MessageBoxImage.Information, MessageBoxResult.OK);
                            this.ID = 0;
                            this.Name = string.Empty;
                            this.Address = string.Empty;
                            this.MobileNo = string.Empty;
                            this.Email = string.Empty;

                        }
                    }
                    else
                    {
                        try
                        {

                            Students.Add(new Student { id = Students.Count + 1, name = this.Name, mobno = this.MobileNo, address = this.Address, email = this.Email });
                            MessageBox.Show("Record Saved.", "WPF MVVM", MessageBoxButton.OK, MessageBoxImage.Information, MessageBoxResult.OK);
                            this.ID = 0;
                            this.Name = string.Empty;
                            this.MobileNo = string.Empty;
                            this.Address = string.Empty;
                            this.Email = string.Empty;
                        }
                        catch (Exception ex)
                        {
                            throw;
                        }
                    }
                }

                public void New()
                {
                    if (Selected != null)
                    {
                        this.ID = 0;
                        this.Name = string.Empty;
                        this.MobileNo = string.Empty;
                        this.Address = string.Empty;
                        this.Email = string.Empty;

                        Selected.id = 0;
                    }
                    Selected = null;
                }

                public void Delete()
                {
                    try
                    {
                        Students.Remove(Selected);
                        this.Name = string.Empty;
                        this.MobileNo = string.Empty;
                        this.Address = string.Empty;
                        this.Email = string.Empty;
                        MessageBox.Show("Record Deleted.", "WPF MVVM", MessageBoxButton.OK, MessageBoxImage.Information, MessageBoxResult.OK);
                    }
                    catch (Exception ex)
                    {

                        throw;
                    }
                }
                #endregion



                public string Error
                {
                    get { throw new NotImplementedException(); }
                }

                public string this[string columnName]
                {
                    get
                    {
                        string result = null;
                        if (columnName == "Name")
                        {
                            if (string.IsNullOrEmpty(Name))
                            {
                                result = "Name Cannot Be Empty";
                                return result;
                            }
                            string st = @"!|@|#|\$|%|\?|\>|\<|\*";
                            if (Regex.IsMatch(Name, st))
                            {
                                result = "special chatachter are not allowed";
                                return result;
                            }


                        }

                        if (columnName == "MobileNo")
                        {
                            if (string.IsNullOrEmpty(MobileNo))
                            {
                                result = "Mobile Can not be empty";
                                return result;
                            }
                            if (MobileNo.Length > 10 || MobileNo.Length < 10)
                            {
                                result = "number should be 10 charachters";
                                return result;
                            }
                            string s1 = @"^[0-9]*$";
                            if (!Regex.IsMatch(MobileNo, s1))
                            {
                                result = "Mobile number contain numeric value ";
                                return result;
                            }
                            else
                            {
                                return null;
                            }

                        }

                        if (columnName == "Address")
                        {
                            if (string.IsNullOrEmpty(Address))
                            {
                                result = "fill your address";
                                return result;
                            }
                        }
                        if (columnName == "Email")
                        {
                            string s1 = @"^[a-zA-Z][\w\.-]{2,28}[a-zA-Z0-9]@[a-zA-Z0-9][\w\.-]*[a-zA-Z0-9]\.[a-zA-Z][a-zA-Z\.]*[a-zA-Z]$";

                            if (string.IsNullOrEmpty(Email))
                            {
                                result = "Email can not be empty";
                                return result;
                            }
                            if (Regex.IsMatch(Email, s1)) //|| Regex.IsMatch(Email, s2))
                            {
                                return null;
                            }
                            else
                            {
                                result = "Not valid email(format: dhru@gmail.com)";
                                return result;

                            }
                        }

                        return null;

                    }
                }
            }
        }

    View - > Student.xaml

    <Window x:Class="WpfDesktopCrud.View.Students"
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            xmlns:VM="clr-namespace:WpfDesktopCrud.ViewModel"
            Title="Students" Height="400" Width="500">
        <Window.DataContext>
            <VM:VMStudent/>
        </Window.DataContext>

        <Grid>
            <Grid.Resources>
                <ControlTemplate x:Key="dTemplate">
                    <StackPanel Orientation="Horizontal">
                        <DockPanel LastChildFill="True">
                            <TextBlock DockPanel.Dock="Right" Text="{Binding AdornedElement.(Validation.Errors).[0].ErrorContent, ElementName=ErrorAdorner}" Background="#FA5858" Foreground="White" FontWeight="Light" VerticalAlignment="Center"/>
                            <AdornedElementPlaceholder VerticalAlignment="Top" x:Name="ErrorAdorner">
                                <Border BorderBrush="Red" BorderThickness="1" />
                            </AdornedElementPlaceholder>
                        </DockPanel>
                    </StackPanel>
                </ControlTemplate>
            </Grid.Resources>
            <Grid.RowDefinitions>
                <RowDefinition Height="*"/>
                <RowDefinition Height="auto"/>
                <RowDefinition Height="Auto"/>
            </Grid.RowDefinitions>

            <ListBox ItemsSource="{Binding Students}" SelectedItem="{Binding Selected}" DisplayMemberPath="name"  SelectedValuePath="id" Margin="0,0,0,26">

            </ListBox>

            <Grid Grid.Row="1" HorizontalAlignment="Center">
                <Grid.Resources>
                    <Style TargetType="TextBlock">
                        <Setter Property="Margin" Value="5 2 5 0"/>
                        <Setter Property="HorizontalAlignment" Value="Right"/>
                    </Style>
                    <Style TargetType="TextBox">
                        <Setter Property="Margin" Value="5 5 5 5"/>
                    </Style>
                </Grid.Resources>
                <Grid.RowDefinitions>
                    <RowDefinition/>
                    <RowDefinition/>
                    <RowDefinition/>
                    <RowDefinition/>
                </Grid.RowDefinitions>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto"/>
                    <ColumnDefinition Width="200"/>
                </Grid.ColumnDefinitions>
                <TextBlock Text="Name"/>
                <TextBlock Text="Mobile No" Grid.Row="1"/>
                <TextBlock Text="Address" Grid.Row="2"/>
                <TextBlock Text="Email" Grid.Row="3"/>
                <TextBox x:Name="txtName" Text="{Binding Name,UpdateSourceTrigger=PropertyChanged,Mode=TwoWay,ValidatesOnDataErrors=True}" Validation.ErrorTemplate="{StaticResource dTemplate}"
                         Grid.Column="1"/>
                <TextBox x:Name="txtNo" Text="{Binding MobileNo,UpdateSourceTrigger=PropertyChanged,Mode=TwoWay,ValidatesOnDataErrors=True}" Validation.ErrorTemplate="{StaticResource dTemplate}"
                         Grid.Row="1" Grid.Column="1"/>
                <TextBox x:Name="txtAdd" Text ="{Binding Address,UpdateSourceTrigger=PropertyChanged,Mode=TwoWay,ValidatesOnDataErrors=True}" Validation.ErrorTemplate="{StaticResource dTemplate}"
                         Grid.Row="2" Grid.Column="1" TextWrapping="WrapWithOverflow" AcceptsReturn="True" ScrollViewer.CanContentScroll="True" VerticalScrollBarVisibility="Auto" Height="90"/>
                <TextBox x:Name="txtEmail" Text ="{Binding Email,UpdateSourceTrigger=PropertyChanged,Mode=TwoWay,ValidatesOnDataErrors=True}" Validation.ErrorTemplate="{StaticResource dTemplate}"
                         Grid.Row="3" Grid.Column="1"/>
            </Grid>

            <WrapPanel Grid.Row="3" HorizontalAlignment="Center" >
                <Button Command="{Binding NewCommand}" Content="New" Width="75" Height="31">
                    <Button.Style>
                        <Style TargetType="{x:Type Button}">
                            <EventSetter Event="Click" Handler="MoveFocusOnClick"/>
                        </Style>
                    </Button.Style>
                </Button>
                <Button Command="{Binding SaveCommand}" Content="Save" Width="75" Height="31">
                    <Button.Style>
                        <Style TargetType="Button">
                            <Setter Property="IsEnabled" Value="False"/>
                            <Style.Triggers>
                                <MultiDataTrigger>
                                    <MultiDataTrigger.Conditions>
                                        <Condition Binding ="{Binding Path=(Validation.HasError),ElementName=txtName}" Value="false"/>
                                        <Condition Binding ="{Binding Path=(Validation.HasError),ElementName=txtNo}" Value="false"/>
                                        <Condition Binding ="{Binding Path=(Validation.HasError),ElementName=txtAdd}" Value="false"/>
                                        <Condition Binding ="{Binding Path=(Validation.HasError),ElementName=txtEmail}" Value="false"/>
                                    </MultiDataTrigger.Conditions>
                                    <Setter Property="IsEnabled" Value="True"/>
                                </MultiDataTrigger>
                            </Style.Triggers>
                        </Style>
                    </Button.Style>
                </Button>
                <Button Command="{Binding DeleteCommand}" Content="Delete" Width="75" Height="31"/>
            </WrapPanel>
        </Grid>
    </Window>


Model -> Student.cs
using GalaSoft.MvvmLight;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace WpfDesktopCrud.Model
{
    class Student : ViewModelBase
    {
        private int _id;

        public int id
        {
            get { return _id; }
            set
            {
                _id = value;
                RaisePropertyChanged("id");
            }
        }
        private string _name;

        public string name
        {
            get { return _name; }
            set
            {
                _name = value;
                RaisePropertyChanged("name");
            }
        }
        private string _mobno;

        public string mobno
        {
            get { return _mobno; }
            set
            {
                _mobno = value;
                RaisePropertyChanged("mobno");
            }
        }
        private string _address;

        public string address
        {
            get { return _address; }
            set
            {
                _address = value;
                RaisePropertyChanged("address");
            }
        }
        private string _email;

        public string email
        {
            get { return _email; }
            set
            {
                _email = value;
                RaisePropertyChanged("email");
            }
        }



        private DateTime _timer;
        public DateTime Timer
        {
            get { return _timer; }
            set
            {
                _timer = value;
                RaisePropertyChanged("timer");
            }
        }


    }
}