WPF.Basic数据验证

 

Validation两种验证方法: ValidationRule +iDataErrorInfo+DataAnimation 的用法

Validation：依赖属性用（在验证回调中返回false）

ValidationRule：依赖属性和普通类的属性都能用
IdataErrorInfo：依赖属性和普通类的属性都能用，谁想用的话 就继承iDataErrorInfo

区别？

ValidationRule可以自定义错误信息，Validation和ValidationRule在xaml中的用法一样，比较繁琐

iDataErrorErrorInfo可以使用属性索引器，在xaml中只需咋binding表达式中打开ValidatesOnDataErrors=True即可，xaml代码比较少

ValidationRule和iDataErrorInfo的错误信息都是被全局静态对象Validation接收的

1.Validation 依赖属性的验证

界面上有2个控件，一个textbox绑定一个自定义的依赖属性，一个textblock绑定前面依赖属性的验证结果

依赖属性都有一个private static bool ValidateValueCallback(object value)验证回调函数，返回值是验证的结果bool类型的，value是依赖属性的数据，在验证回调中做一下判断，当不满足条件时，返回一个false，

这时候全局静态对象Validation就能捕获到这个验证结果

<TextBox Name="tb">
　　<TextBox.Text>
 　　　　<Binding Path="MyProperty" UpdateSourceTrigger="PropertyChanged">
　　　　　　<Binding.ValidationRules>
　　　　　　　　<ExceptionValidationRule/>
　　　　　　</Binding.ValidationRules>
　　　　</Binding>
　　</TextBox.Text>
</TextBox>
<TextBox Text="{Binding Path=(Validation.Errors)[0].ErrorContent,ElementName=tb}"/>-->

在依赖属性的验证回调中判断，

运行结果

 2.ValidationRule 依赖属性的验证

上面的验证信息（“123456”不是属性“Myproperty”的有效值）是由ExceptionValidationRule默认提供的错误提示消息

 错误信息能不能自定义呢？这时候要自己写一个ValidationRule

可以看到ExceptionValidationRule也是继承自ValidationRule的

新建一个类继承自ValidationRule，重写ValidationResult

 那怎么用自己定义的去代替ExceptionValidationRule？

运行结果：

 

 3.iDataErrorInfo和DataAnnotations特性

普通属性所在的类继承iDataErrorInfo，并实现iDataErrorInfo提供的接口和索引器

 public class Person : INotifyPropertyChanged, IDataErrorInfo
    {
        private int _id;
        private string _name;
    </span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">string</span><span style="color: rgba(0, 0, 0, 1)"> Name
    {
        </span><span style="color: rgba(0, 0, 255, 1)">get</span> { <span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> _name; }
        </span><span style="color: rgba(0, 0, 255, 1)">set</span> { _name =<span style="color: rgba(0, 0, 0, 1)"> value;
            PropertyChanged</span>?.Invoke(<span style="color: rgba(0, 0, 255, 1)">this</span>, <span style="color: rgba(0, 0, 255, 1)">new</span> PropertyChangedEventArgs(<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">Name</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">));
        }
    }

    </span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> ID
    {
        </span><span style="color: rgba(0, 0, 255, 1)">get</span> { <span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> _id; }
        </span><span style="color: rgba(0, 0, 255, 1)">set</span> { _id =<span style="color: rgba(0, 0, 0, 1)"> value;
            PropertyChanged</span>?.Invoke(<span style="color: rgba(0, 0, 255, 1)">this</span>, <span style="color: rgba(0, 0, 255, 1)">new</span> PropertyChangedEventArgs(<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">ID</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">));
        }
    }

    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">INotifyPropertyChanged的接口</span>
    <span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">event</span> PropertyChangedEventHandler?<span style="color: rgba(0, 0, 0, 1)"> PropertyChanged;
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">IDataErrorInfo的接口</span>
    <span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">string</span> Error { <span style="color: rgba(0, 0, 255, 1)">get</span> { <span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(128, 0, 0, 1)">""</span><span style="color: rgba(0, 0, 0, 1)">; } }

    </span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">string</span> <span style="color: rgba(0, 0, 255, 1)">this</span>[<span style="color: rgba(0, 0, 255, 1)">string</span><span style="color: rgba(0, 0, 0, 1)"> columnName]
    {
        </span><span style="color: rgba(0, 0, 255, 1)">get</span><span style="color: rgba(0, 0, 0, 1)">
        {
             </span><span style="color: rgba(0, 0, 255, 1)">if</span> (columnName == <span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">ID</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">)
            {
                   </span><span style="color: rgba(0, 0, 255, 1)">if</span> (_id &gt;<span style="color: rgba(128, 0, 128, 1)">18</span><span style="color: rgba(0, 0, 0, 1)">)
                {
                    </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">&gt;18</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">;
                }
            }

             </span><span style="color: rgba(0, 0, 255, 1)">if</span> (columnName == <span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">Name</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">)
            {
                </span><span style="color: rgba(0, 0, 255, 1)">if</span> (Name.Length &gt; <span style="color: rgba(128, 0, 128, 1)">3</span><span style="color: rgba(0, 0, 0, 1)">)
                    </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">leng&gt;3</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">;
            }

             </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(0, 0, 255, 1)">string</span><span style="color: rgba(0, 0, 0, 1)">.Empty;
        }
    }
}</span></pre>

Person类提供了2个属性，继承了iDataErrorInfo，在索引器中判断每个属性的值是否符合要求，在索引器中的return 返回的值会被全局静态对象Validation接受，这是binding表达式提供的功能，会在绑定的目标和数据源之间检测是否存在检验信息，在控件上如何获取呢？

只需要在需要接受验证的对象上打开

ValidatesOnDataErrors=True,ValidatesOnExceptions=True

xaml代码：

<Grid>
        <StackPanel>
            <Label Content="ID"/>
            <TextBox x:Name="tb" Text="{Binding ID, UpdateSourceTrigger=PropertyChanged,Mode=TwoWay,ValidatesOnDataErrors=True,ValidatesOnExceptions=True}"/>
            <TextBox Text="{Binding Path=(Validation.Errors)[0].ErrorContent,ElementName=tb}"/>
            <Label Content="Name"/>
            <TextBox x:Name="tbname" Text="{Binding Name,UpdateSourceTrigger=PropertyChanged,Mode=TwoWay,ValidatesOnDataErrors=True,ValidatesOnExceptions=True}"/>
            <TextBox Text="{Binding Path=(Validation.Errors)[0].ErrorContent,ElementName=tbname}"/>
        </StackPanel>
    </Grid>

运行结果：

 

 

 当使用IdataErrorInfo时，需要在索引器中以此判断每个属性和属性的值，为了简化索引器中的代码，通过反射去获取每个属性，并通过添加特性的方法去完成验证

 public class Person : INotifyPropertyChanged, IDataErrorInfo
    {
        private int _id;
        private string _name;
        [Required]
        [MyArrtibute ]
        public string Name
        {
            get { return _name; }
            set
            {
                _name = value;
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs("Name"));
            }
        }
        [Range(0,18,ErrorMessage ="超出范围了")]
        [Required]
        public int ID
        {
            get { return _id; }
            set
            {
                _id = value;
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs("ID"));
            }
        }
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">INotifyPropertyChanged的接口</span>
    <span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">event</span> PropertyChangedEventHandler?<span style="color: rgba(0, 0, 0, 1)"> PropertyChanged;
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">IDataErrorInfo的接口</span>
    <span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">string</span> Error { <span style="color: rgba(0, 0, 255, 1)">get</span> { <span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(128, 0, 0, 1)">""</span><span style="color: rgba(0, 0, 0, 1)">; } }
    </span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">string</span> <span style="color: rgba(0, 0, 255, 1)">this</span>[<span style="color: rgba(0, 0, 255, 1)">string</span><span style="color: rgba(0, 0, 0, 1)"> columnName]
    {
        </span><span style="color: rgba(0, 0, 255, 1)">get</span><span style="color: rgba(0, 0, 0, 1)">
        {
            </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">引入命名空间using System.ComponentModel.DataAnnotations;</span>
            <span style="color: rgba(0, 0, 255, 1)">var</span> vc = <span style="color: rgba(0, 0, 255, 1)">new</span> ValidationContext(<span style="color: rgba(0, 0, 255, 1)">this</span>, <span style="color: rgba(0, 0, 255, 1)">null</span>, <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">);
            vc.MemberName </span>=<span style="color: rgba(0, 0, 0, 1)"> columnName;
            </span><span style="color: rgba(0, 0, 255, 1)">var</span> res = <span style="color: rgba(0, 0, 255, 1)">new</span> List&lt;ValidationResult&gt;<span style="color: rgba(0, 0, 0, 1)">();
            </span><span style="color: rgba(0, 0, 255, 1)">var</span> result = Validator.TryValidateProperty(<span style="color: rgba(0, 0, 255, 1)">this</span>.GetType().GetProperty(columnName).GetValue(<span style="color: rgba(0, 0, 255, 1)">this</span>, <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">), vc, res);
            </span><span style="color: rgba(0, 0, 255, 1)">if</span> (res.Count &gt; <span style="color: rgba(128, 0, 128, 1)">0</span><span style="color: rgba(0, 0, 0, 1)">)
            {
                </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(0, 0, 255, 1)">string</span>.Join(Environment.NewLine, res.Select(r =&gt;<span style="color: rgba(0, 0, 0, 1)"> r.ErrorMessage).ToArray());
            }
            </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(0, 0, 255, 1)">string</span><span style="color: rgba(0, 0, 0, 1)">.Empty;
        }
    }
}</span></pre>

一个类继承了IdataErrorInfi后，又使用DataAnnotations去改善索引器后，属性的验证逻辑需要通过特性的方式去完成，特性分为系统自带的和自定义的，新建特性的方法，新建一个类并继承ValidationAttribute，在该类中返回一个ValidationResult即可。

新建特性代码：

public class MyArrtibute : ValidationAttribute
    {
        protected override ValidationResult? IsValid(object? value, ValidationContext validationContext)
        {
            if (value.ToString().Length > 10)
                return new ValidationResult("名字长度大于10了");
        </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(0, 0, 255, 1)">base</span><span style="color: rgba(0, 0, 0, 1)">.IsValid(value, validationContext);
    }
}</span></pre>

第一个参数value就是在binding表达式，从数据源到目标的值，这里的return返回的值依旧是被全局静态对象Validation接受，这是由binding功能提供的

特性的使用方法：

　　　　[Required]
        [MyArrtibute ]
        public string Name
        {
            get { return _name; }
            set
            {
                _name = value;
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs("Name"));
            }
        }

在需要验证的属性前加上特性即可

运行结果：