Comments for Notes on Software http://softnotes.wordpress.com Thu, 25 Sep 2008 20:10:50 +0000 http://wordpress.com/ hourly 1 Comment on Validation in WPF with .NET 3.5 SP1 by Using BindingGroup in custom controls « Notes on Software http://softnotes.wordpress.com/2008/08/20/validation-in-wpf-with-net-35-sp1/#comment-14 Using BindingGroup in custom controls « Notes on Software Thu, 25 Sep 2008 20:10:50 +0000 http://softnotes.wordpress.com/?p=15#comment-14 [...] above fails. But this binding error does not participate in the validation mechanism (look at my earlier post on validation for a pattern for implementing validation). The solution is to find a BindingGroup [...] [...] above fails. But this binding error does not participate in the validation mechanism (look at my earlier post on validation for a pattern for implementing validation). The solution is to find a BindingGroup [...]

]]> Comment on Validation in WPF with .NET 3.5 SP1 by [WPF] Validation des données, du nouveau avec le 3.5 SP1 , Elise's blog http://softnotes.wordpress.com/2008/08/20/validation-in-wpf-with-net-35-sp1/#comment-12 [WPF] Validation des données, du nouveau avec le 3.5 SP1 , Elise's blog Thu, 11 Sep 2008 15:18:32 +0000 http://softnotes.wordpress.com/?p=15#comment-12 [...] parallèle, un autre blog poste le détail d'une solution de validation des données, toujours en utilisant le BindingGroup  [...] [...] parallèle, un autre blog poste le détail d’une solution de validation des données, toujours en utilisant le BindingGroup  [...]

]]> Comment on Validation in WPF with .NET 3.5 SP1 by K. M. http://softnotes.wordpress.com/2008/08/20/validation-in-wpf-with-net-35-sp1/#comment-7 K. M. Thu, 21 Aug 2008 20:37:39 +0000 http://softnotes.wordpress.com/?p=15#comment-7 Karl, I am recommending throwing exceptions <b>only when property level validation logic is violated</b>, that is when a value is being set that can <b>never</b> be valid, irrespective of the values of other properties. An example would be when an Age property is set to a negative value. If a value is being set that puts the object in an invalid state because of <b>inter-property</b> requirements, exceptions <b>should not</b> be thrown. Note that I also return null in the IDataErrorInfo indexer. There are no property level errors for IDataErrorInfo to report in my approach. I use IDataErrorInfo for its Error property, which returns all object-level errors. This makes the error logic cleaner. I can put validation logic that depends on three properties at a single place in the Error property instead of thrice in the indexer. Hope that makes my reasoning clear. Thanks for the feedback. K. M. Karl,
I am recommending throwing exceptions only when property level validation logic is violated, that is when a value is being set that can never be valid, irrespective of the values of other properties. An example would be when an Age property is set to a negative value. If a value is being set that puts the object in an invalid state because of inter-property requirements, exceptions should not be thrown.
Note that I also return null in the IDataErrorInfo indexer. There are no property level errors for IDataErrorInfo to report in my approach. I use IDataErrorInfo for its Error property, which returns all object-level errors. This makes the error logic cleaner. I can put validation logic that depends on three properties at a single place in the Error property instead of thrice in the indexer.
Hope that makes my reasoning clear.
Thanks for the feedback.

K. M.

]]> Comment on Validation in WPF with .NET 3.5 SP1 by Karl Shifflett http://softnotes.wordpress.com/2008/08/20/validation-in-wpf-with-net-35-sp1/#comment-6 Karl Shifflett Thu, 21 Aug 2008 19:39:43 +0000 http://softnotes.wordpress.com/?p=15#comment-6 Why are you recommending throwing exceptions from property setters when your also implementing IDataErrorInfo? "Apply property level validation logic in the property setters of the domain objects. Throw exceptions when the logic is violated." I have a complete write up on this on my blog at: http://karlshifflett.wordpress.com/2008/04/20/fort-knox-business-objects-yes-no/ I'm seeing this practice in a number of spaces and really can't understand why this is being recommended. Thanks for you feedback and have a great day, Karl Why are you recommending throwing exceptions from property setters when your also implementing IDataErrorInfo?

“Apply property level validation logic in the property setters of the domain objects. Throw exceptions when the logic is violated.”

I have a complete write up on this on my blog at: http://karlshifflett.wordpress.com/2008/04/20/fort-knox-business-objects-yes-no/

I’m seeing this practice in a number of spaces and really can’t understand why this is being recommended.

Thanks for you feedback and have a great day,

Karl

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