WPF:解决数据验证ValidationRule与按钮Canexcute联动的问题
Posted swobble
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想法是这样的,
如果用户输入有误,界面上显示ValidationRule的提示,并且按钮enabled=false(canExcute=fales)
按钮是在输入信息属性改变时刷新Canexcute方法
实际中validRule:RequiredNumberValidRule ValidatesOnTargetUpdated="True"默认是先验证再赋值,如果验证不通过就不赋值,
这就造成了如果验证不通过不能执行Canexcute而按钮无法enabled=false
此时需要更改ValidationRule的属性,设置ValidationStep="UpdatedValue"或者CommiteVALUE
此时还是不行,设置ValidationStep="UpdatedValue后,绑定的属性就变成了绑定的表达式了,
参考:https://stackoverflow.com/questions/10342715/validationrule-with-validationstep-updatedvalue-is-called-with-bindingexpressi
改写了下代码,成功!
····
<TextBox Grid.Column="2" Height="26" >
<Binding Path="Compare_Correlation" UpdateSourceTrigger="PropertyChanged">
<Binding.ValidationRules>
<validRule:RequiredNumberValidRule ValidatesOnTargetUpdated="True" ValidationStep="UpdatedValue" />
</Binding.ValidationRules>
</Binding>
</TextBox>
public class RequiredNumberValidRule : ValidationRule
{
public override ValidationResult Validate(object value, CultureInfo cultureInfo)
{
if (GetBoundValue(value) is null)
{
return new ValidationResult(false, "required field.");
}
var temp = GetBoundValue(value).ToString();
double doubleValue;
if (double.TryParse(temp, out doubleValue))
{
return new ValidationResult(true, null);
}
else
{
return new ValidationResult(false, "Incorrect number format.");
}
}
private object GetBoundValue(object value)
{
if (value is BindingExpression)
{
// ValidationStep was UpdatedValue or CommittedValue (Validate after setting)
// Need to pull the value out of the BindingExpression.
BindingExpression binding = (BindingExpression)value;
// Get the bound object and name of the property
object dataItem = binding.DataItem;
string propertyName = binding.ParentBinding.Path.Path;
// Extract the value of the property.
object propertyValue = dataItem.GetType().GetProperty(propertyName).GetValue(dataItem, null);
// This is what we want.
return propertyValue;
}
else
{
// ValidationStep was RawProposedValue or ConvertedProposedValue
// The argument is already what we want!
return value;
}
}
}
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