WPF 后台触发 Validate UI‘s Element · WPF编程之路

wpf中有validateRule类，用于界面元素的验证，如何后台去控制validateRule呢？ 1. UI层要binding写好的ValidateRule，分为Binding和MultiBinding，如下面分别实现了Combobox的SelectedValuePropperty的Binding 和TextBox的TextProperty的MultiBinding。其中都有ValidationRule。 <ComboBoxx:Name="cmbAgeType"Margin="3" SelectionChanged="cmbAgeType_SelectionChanged" Background="#00000000"BorderBrush="Black"Grid.Row="4"MinWidth="0"Grid.Column="2"IsTabStop="False"SelectedIndex="0"d:LayoutOverrides="GridBox"Tag="PatientAge" Visibility="{BindingDataContext,ElementName=window,Converter={StaticResourceKeyToVisibilityConverter},ConverterParameter=PatientAge}"> <ComboBox.SelectedValue> <BindingPath="PatientAge"Converter="{StaticResourceAgeMeasureConverter}"Mode="TwoWay" UpdateSourceTrigger="PropertyChanged"> <Binding.ValidationRules> <McsfPAFEContainee_ValidationRules:EmptyValidationRuleValidatesOnTargetUpdated="True"ValidationStep="ConvertedProposedValue"/> </Binding.ValidationRules> </Binding> </ComboBox.SelectedValue>  </ComboBox> <TextBoxx:Name="txtPatientWeight"TextWrapping="Wrap"Margin="3"MaxLength="10"TabIndex="6"BorderBrush="Black"Grid.Row="5"Grid.Column="1"Height="22"MinWidth="42"Tag="PatientWeight" Visibility="{BindingDataContext,ElementName=window,Converter={StaticResourceKeyToVisibilityConverter},ConverterParameter=PatientWeight}"> <TextBox.Text> <MultiBinding Mode="TwoWay"Converter="{StaticResourceWeightConverter}" UpdateSourceTrigger="PropertyChanged"> <MultiBinding.ValidationRules> <McsfPAFEContainee_ValidationRules:WeightValidationRuleValidatesOnTargetUpdated="True"ValidationStep="ConvertedProposedValue"/> </MultiBinding.ValidationRules> <BindingPath="PatientWeight"/> <BindingPath="IsChecked"ElementName="rdoKg"/> </MultiBinding> </TextBox.Text> <i:Interaction.Behaviors> <McsfPAFEContainee_Behaviors:NumericTextBoxBehaviorMinValue="0"MaxValue="300" /> </i:Interaction.Behaviors> </TextBox> 2. 后台主动触发ValidationRule的验证。以下方法根据上面的Binding，分别去取Binding和MultiBinding，然后调用UpdateSource。 privateboolValidateInput(objectchild,PRCfgViewModelvm,boolisUpdateSource,boolisEmergency) { BindingExpressionbe =null; MultiBindingExpressionmbe =null; if(childisTextBox) { be = (childasTextBox).GetBindingExpression(TextBox.TextProperty); if(null== be) { mbe =BindingOperations.GetMultiBindingExpression((childasTextBox),TextBox.TextProperty); } } elseif(childisDatePicker) { be = (childasDatePicker).GetBindingExpression(DatePicker.TextProperty); if(null== be) { mbe =BindingOperations.GetMultiBindingExpression((childasDatePicker),DatePicker.TextProperty); } } elseif(childisComboBox) { be = (childasComboBox).GetBindingExpression(ComboBox.SelectedValueProperty); if(null== be) { mbe =BindingOperations.GetMultiBindingExpression((childasComboBox),ComboBox.SelectedValueProperty); } } if(null== be &&null== mbe) { returnfalse; } ValidationRulevr =null; if(null!= be && be.ParentBinding.ValidationRules.Count > 0) { vr = be.ParentBinding.ValidationRules[0]; } elseif(null!= mbe && mbe.ParentMultiBinding.ValidationRules.Count > 0) { vr = mbe.ParentMultiBinding.ValidationRules[0]; } else { returnfalse; } stringbindingPath =""; if(null!= be) { bindingPath = be.ParentBinding.Path.Path; } elseif(null!= mbe) { Bindingbd = mbe.ParentMultiBinding.Bindings[0]asBinding; bindingPath = bd.Path.Path; } bindingPath = bindingPath.Replace(".","_"); if(vm.Setting.CfgInfo[bindingPath] !=null) { (vrasBaseValidationRule).IsActive = !isEmergency; if((vrasBaseValidationRule).IsActive) { (vrasBaseValidationRule).IsAllowEmpty = !(vm.Setting.CfgInfo[bindingPath].IsKeyword); } else { if(isUpdateSource) { if(null!= be) { be.UpdateSource(); } elseif(null!= mbe) { mbe.UpdateSource(); } } returntrue; } } else { (vrasBaseValidationRule).IsAllowEmpty =true; } if(isUpdateSource) { if(null!= be) { be.UpdateSource(); } elseif(null!= mbe) { mbe.UpdateSource(); } } returntrue; }