How to show Validation Error Message on GridView level

2 posts, 0 answers
  1. NayLin
    NayLin avatar
    5 posts
    Member since:
    Feb 2016

    Posted 17 Mar 2016 Link to this post

    I have learned that RadGridView has data validation feature per cell and row. But in my case, I want data validation on GridView level. In my app, I have "Purchase Order Form". In this form, there is RadGridView for Purchase Order Items. The validation scenario is User must add at least one item to this RadGridView.

    I use the way of Data Annotation and Validation Attribute in my ViewModel to check this validation.

    [CollectionHasElements( ErrorMessage = "Purchase order must have at least one order item." )]
            public ObservableCollection<PurchaseOrderItemDecorator> PurchaseOrderItemDecorators
                get { return _purchaseOrderItemDecorator; }
                set { SetProperty( ref _purchaseOrderItemDecorator, value ); }

    The RadGridView successfully notify the error by showing Red Border around the grid. But it somehow failed to show the error message. I attached the screenshot of this RadGridView.

    In normal telerik wpf controls, it usually shows the error message on top right corner red block triangle. I wish my Gridview act like that for showing validation error message.


  2. Stefan
    Stefan avatar
    771 posts

    Posted 21 Mar 2016 Link to this post

    Hello NayLin,

    I tried achieving such behavior of the control when validating it through a ValidationAttribute, but to no avail. RadGridView performs its validation on row level, which is the expected behavior. You can check out the attached demo application as a demonstration.

    As to achieving the desired result, a possible solution might be to subscribe to the CellValidating event and within the event handler set the BorderBrush of the control to "Red".  Then, you can define a property in the view model to which the ToolTip showing the error message will be bound. In order to position the ToolTip in the top right corner of RadGridView, I suggest you taking a look at this and this StackOverflow threads. You may also find this MSDN article useful on the matter.

    Stefan X1
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