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Mastering Windows Presentation Foundation

You're reading from   Mastering Windows Presentation Foundation Master the art of building modern desktop applications on Windows

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Product type Paperback
Published in Feb 2017
Publisher Packt
ISBN-13 9781785883002
Length 568 pages
Edition 1st Edition
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Author (1):
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Sheridan Yuen Sheridan Yuen
Author Profile Icon Sheridan Yuen
Sheridan Yuen
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Table of Contents (13) Chapters Close

Preface 1. A Smarter Way of Working with WPF 2. Debugging WPF Applications FREE CHAPTER 3. Writing Custom Application Frameworks 4. Becoming Proficient with Data Binding 5. Using the Right Controls for the Job 6. Mastering Practical Animations 7. Creating Visually Appealing User Interfaces 8. Implementing Responsive Data Validation 9. Completing That Great User Experience 10. Improving Application Performance 11. Deploying Your Masterpiece Application 12. What Next?

Avoiding UI-based validation errors


In the last example from the previous section, we data bound the whole Validation.Errors collection to a tooltip in the error template for our textbox. We also data bound our own Errors collection from our base class to the items control above the form fields.

Our Errors collection can display all of the errors for all of the properties in each data model. However, the Validation.Errors collection has access to UI-based validation errors that never make it back to the View Models. Take a look at the following example:

The UI-based validation error says Value '0t' could not be converted and that explains why the View Models never see this error. The type of value expected in the data bound property is decimal, but an unconvertible value has been entered. Therefore, the input value cannot be converted to a decimal and so, the data bound value is never updated.

However, the Validation.Errors collection is a UI element and each data bound control has its own...

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