Textarea not validating

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Please help me with the required code This is Xaml code: , you can do the validation in that instead of the setter of a particular property, then whenever there is a error, return an error message so that the text box which has the error gets a red box around it, indicating an error.To get it done only with XAML you need to add Validation Rules for individual properties.Correspondingly, an underlying data value in the view model is automatically updated when the user modifies the bound value in the view.Provided that the view model has a property called “Name”, you bind it to a Text Box’s Text property in XAML the following way: Besides the path that specifies the name of the property to bind to, the binding must also have a source object. I need validations for my Text Box, it should show errors as I enter wrong characters or integers.Also can this be done only in Xaml without codebehind?And use error template to display your errors to user in UI.

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The latter can for example be very useful for bindings in Styles and Control Templates and when you want to bind to some property in a parent element.You can do this by implementing a custom validation rule and associate this with the object at any given step, any errors that were added to the Validation.Errors attached property of the bound element during that step in a previous validation procedure are removed. Errors collection is also cleared when a valid value transfer occurs.Once you have created a converter class you will typically add it as a resource in XAML with a unique x: Key attribute and then reference it from the binding as a Static Resource: (string) to a dependency property of type string you don’t necessarily need to use a converter as the default conversion will automatically apply the To String() method on the value of the source property.This means that you don’t have to use a converter to display a If a user enters an invalid value that cannot be converted to an int and be set as the value for the Age property in the view model in the above example, a validation error will occur and a visual feedback will be provided to the user to indicate this.

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