Validating data in wpf

30-May-2017 04:07

validating data in wpf-71

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One request I saw was to compare two date fields “start” and “end” date and to validate that the end date was later than the start date – that can easily be accomplished using this.

The source code is almost fully documented, so hopefully that clears any question marks you might have up Programming enthusiast.

As I mentioned in a previous post, you can specify validation by creating a Validation class (or classes).

You do this by deriving a new class from the Validation Rule class and overriding the Validate method.

The user must enter a valid value or hit Escape to reject changes before exiting edit mode.

This is how the control behaves by default; however, every Editable Column object has an Allow Editing Validation property that you can set to enable/disable validation.

The combination of these two is what makes it possible to be aware of the view-model instance which is being validated, coincidentally providing us access to all of its properties as well.In order to make the Text Boxes worry about validation, we need to use the `Validates On Data Errors´ binding property as you can see above.Moving on to the Validation View Model and cross-field validation, I want to bring special focus to the Validation Attribute.For example, you can create a dummy data binding and apply validation for this binding.

The xam Grid™ control supports data validation; anytime your end user sets a value that causes an exception and tries to exit edit mode, the control displays the exception and keeps the user in edit mode.Why would you do this, instead of implementing IData Error Info?Well, if you wanted to do validation across a number of objects, then this is the way to go.By specifying it in the Validation Rules element of your binding – just like IData Error Info.