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Ticket T270563
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How to avoid the "permissionRequest.TargetObject incompatible with targetObject.GetType()" error thrown from DeleteObjectsViewController when displaying several ITreeNode implementors in Tree List Editors

created 10 years ago

Hi,

We have a business object of type ITreeNode. The children it returns are of a different type.

When selecting one of these children in the tree list editor of the list view, the DeleteObjectsViewController will crash (only if you don't have the "IsAdministrator" permission).

Code from DelteObjectsViewController line 130+

C#
if(((ObjectView)View).SelectedObjects.Count == 1) {  
    isDeleteGrantedForAllSelectedObjects = DataManipulationRight.CanDelete(((ObjectView)View).ObjectTypeInfo.Type, ((ObjectView)View).SelectedObjects[0], LinkToListViewController.FindCollectionSource(Frame), View.ObjectSpace);  
}  
else {  
    isDeleteGrantedForAllSelectedObjects = DataManipulationRight.CanDelete(((ObjectView)View).ObjectTypeInfo.Type, null, LinkToListViewController.FindCollectionSource(Frame), View.ObjectSpace);

There the DataManipulationRight.CanDelete is checked with ((ObjectView)View).ObjectTypeInfo.Type. However, this does not match the selected object type. And therefore this function will throw an exception.

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Answers approved by DevExpress Support

created 10 years ago (modified 9 years ago)

Hello Stefan,

SYMPTOMS
You are likely referring to the following error:

Type: InvalidCastException     Message: permissionRequest.TargetObject incompatible with targetObject.GetType()     Data: 0 entries     Stack trace:
bij DevExpress.ExpressApp.Security.ServerPermissionRequestProcessor.GetTypeToProcess(Type targetType, Object targetObject) bij DevExpress.ExpressApp.Security.ServerPermissionRequestProcessor.IsGrantedCore(ServerPermissionRequest permissionRequest, IPermissionDictionary permissions, Boolean needToCheckBackReference) bij DevExpress.ExpressApp.Security.ServerPermissionRequestProcessor.DevExpress.ExpressApp.Security.IPermissionRequestProcessor.IsGranted(IPermissionRequest permissionRequest) bij DevExpress.ExpressApp.Security.ClientPermissionRequestProcessor.IsGranted(ClientPermissionRequest clientPermissionRequest) bij DevExpress.ExpressApp.Security.ClientPermissionRequestProcessor.DevExpress.ExpressApp.Security.IPermissionRequestProcessor.IsGranted(IPermissionRequest permissionRequest) bij DevExpress.ExpressApp.Security.SelectDataSecurity.IsGranted(IPermissionRequest permissionRequest) bij DevExpress.ExpressApp.Security.SecurityStrategy.IsGranted(IPermissionRequest permissionRequest) bij DevExpress.ExpressApp.DataManipulationRight.IsPermissionGranted(IPermissionRequest permissionRequest) bij DevExpress.ExpressApp.DataManipulationRight.HasPermissionTo(Type objectType, String memberName, Object targetObject, IObjectSpace objectSpace, String operation) bij DevExpress.ExpressApp.DataManipulationRight.CanDelete(Type type, Object targetObject, CollectionSourceBase collectionSourceBase, IObjectSpace objectSpace) bij DevExpress.ExpressApp.SystemModule.DeleteObjectsViewController.UpdateActionState() bij DevExpress.ExpressApp.SystemModule.DeleteObjectsViewController.DoUpdateActionState() bij DevExpress.ExpressApp.SystemModule.DeleteObjectsViewController.View_SelectionChanged(Object sender,

CAUSE
The problem itself is not related to the DeleteObjectsViewController  class, but rather to the fact that you are displaying several ITreeNode objects of non-assignable types within the same TreeListEditor. This is an unsupported configuration and there is a note about this specificity in the TreeListEditors module documentation:
    The TreeListEditor and CategorizedListEditor cannot properly display a tree if the hierarchy contains objects of a type not assignable from the List View object type (see Type.IsAssignableFrom). .
In addition, see a note from this help article:
    There are two important requirements the business classes must satisfy:
    •The parent and child classes that correspond to tree list nodes should inherit the same base class that implements the ITreeNode interface. In the code above, the ProjectGroup, Project and ProjectArea classes are inherited from the Category     class.
   •It is not possible to have more than one root class in a tree list. In the code above, the ProjectGroup is the root class.

RESOLUTION
So, to avoid this error, which is not related to security at all (it was just a consequence), you will need to modify your code to comply with the aforementioned conditions and also use the TreeListEditor with the a ListView of the base type for all ITreeNode implementors, e.g. BaseCategory_ListView. Using the TreeListEditor with the ListView of a descendant type is possible only if it is guaranteed that it will not contain other non-assignable descendants.

P.S.
We have also been reported of a rare scenario with fully custom List Editor implementations where the error with a similar callstack can occur. You can learn more on possible solutions from these tickets:
InvalidCastException (permissionRequest.TargetObject incompatible with targetObject.GetType()) occurs with a custom banded list editor
The "permissionRequest.TargetObject incompatible with targetObject.GetType()" error occurs in MasterDetailViewController with a custom master-detail implementation from eXpand Framework

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