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.NET Forum / Windows Forms / WinForm Data Binding / October 2004problem with databinding collection to datagrid
Hi I have a collection that inherits from collectonbase, implements IBindingList. and is serlizable. I am binding the collection to a Datagrid using a tablestyle to limit the data the datagrid displays. I can bind to the collection successfully. If my collection has one object. When I click on the new row, it adds an object with the addnew method as it should. If I then click on an existing row the new row (where I did not enter any information) shows as a new row (*) again, but the collection still has the new object appended to it (two objects in total). If I then click on the new row, again, the collection adds an object (now having 2 new object). If I reclick on an existing row, again the new appended row returns to the new state (*), showing only one existing object, but the collection has three. Has anybody had an issue like this. Am I missing an interface that the datagrid needs to synchronize successfully with the bound collection. HELP!! Jeff B. Hi, Try having the class stored in the collection implement ieditableobject. http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlr fsystemcomponentmodelieditableobjectclasstopic.asp Ken ---------------------------- Hi I have a collection that inherits from collectonbase, implements IBindingList. and is serlizable. I am binding the collection to a Datagrid using a tablestyle to limit the data the datagrid displays. I can bind to the collection successfully. If my collection has one object. When I click on the new row, it adds an object with the addnew method as it should. If I then click on an existing row the new row (where I did not enter any information) shows as a new row (*) again, but the collection still has the new object appended to it (two objects in total). If I then click on the new row, again, the collection adds an object (now having 2 new object). If I reclick on an existing row, again the new appended row returns to the new state (*), showing only one existing object, but the collection has three. Has anybody had an issue like this. Am I missing an interface that the datagrid needs to synchronize successfully with the bound collection. HELP!! Jeff B. You can find a sample code in this thread http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=FBimDanzDHA .3564%40cpmsftngxa07.phx.gbl Jacob > Hi, > [quoted text clipped - 25 lines] > > Jeff B. The implementation of IBindingList in this example is not entirely correct. That is probably why this example has been removed from the current version of MSDN. The problem is that according to IBindingList MSDN doc "When you call the AddNew method, you should raise a ListChanged event with the ItemAdded enumeration carrying the appropriate index. The added row is in a state where pressing the ESC on a DataGrid control can remove the new row. Raising the ListChanged event with the ItemAdded enumeration a second time on this row indicates that the item is now a row not in the "new" state" In essence, the implementation of IBindingList should be statefull. When new row is created ListChanged should fe fired twice - once with AddItem parameter and second time with ether AddItem or RemoveItem depending of what was the reult of item editing (EndEdit/CancelEdit) If you use an example as is everything looks ok at a first glance, however you will notice that the collection grows in size as you move focus away from the grid and back. If you delete any of the newly created rows you may encounter “Index Out Of Range” exception or other data binding issues I have working sample now for anyone who's interested. Boris I have similar type of problems when using MSDN example. It gives me stackoverflow exception when assigning the datasource to my own collection for the datagrid. Please send me some sample program at sameer.khanna@ihealthcareinc.co.in. Thanks I have a similar type of problem but i got stackoverflow exception. i have used the msdn example. please send me some good samples. sameer.khanna@ihealthcareinc.co.in thanks...sameer Boris, I came across your message in my attempt to implement IBindingList. I would love to see the sample code you have! Do you implement Find and the other methods that typically throw an exception? TYIA, Knut > The implementation of IBindingList in this example is not entirely correct. > That is probably why this example has been removed from the current version [quoted text clipped - 18 lines] > > Boris Hi Knut We don't implement Find and others. Please send an e-mail to boris@NOSPAM.qbf.com.au and i'll reply with the sample cheers boris > Boris, > [quoted text clipped - 38 lines] > > > > Boris BorisDotNet You said : "The implementation of IBindingList in this example is not entirely correct. That is probably why this example has been removed from the current version of MSDN. The problem is that according to IBindingList MSDN doc "When you call the AddNew method, you should raise a ListChanged event with the ItemAdded enumeration carrying the appropriate index. The added row is in a state where pressing the ESC on a DataGrid control can remove the new row. Raising the ListChanged event with the ItemAdded enumeration a second time on this row indicates that the item is now a row not in the "new" state" In essence, the implementation of IBindingList should be statefull. When new row is created ListChanged should fe fired twice - once with AddItem parameter and second time with ether AddItem or RemoveItem depending of what was the reult of item editing (EndEdit/CancelEdit) If you use an example as is everything looks ok at a first glance, however you will notice that the collection grows in size as you move focus away from the grid and back. If you delete any of the newly created rows you may encounter ???Index Out Of Range??? exception or other data binding issues I have working sample now for anyone who's interested. Boris". Can you sendme a simple sample of class and collection where IBindingList and IEditableObject and correctly implemented ? You can find me at M_Duarte at yahoo.com Thanks ;-) Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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