By Andria Jensen - 8/27/2007
I have a BO on my form which uses a few other BOs to get property and the like. I would like to have properties on my primary BO which point to properties on the secondary BO. For example if I have a secondary BO called Clients which is linked by the ClientKey on the primary/seconday BO, and want to get the Client Description I would have a property like this:Public ReadOnly Property ClientDescription as String
Get
Return Clients.Description
End Get
End Property The question I have is how I keep Clients looking at the right record when I am navigating around in the primary BO. I fill the Clients BO with all clients in the Fill of the primary BO and I have some code in the Navigated and CurrentDataTableRefilled event handlers to navigate Clients to the correct primary key when the primary BO record changes. My problem is that when I get into the Navigated event my Clients.Count is 0. When it starts the Fill method the Client count is a few hundred, but it clears it out somewhere along the way. Any idea what I am doing wrong here, or if there is a better way of doing what I'm trying to accomplish? I can't really use the parent/child relationship here because it doesn't make sense in other areas of the database/code.
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By Greg McGuffey - 8/27/2007
Have you checked the count in the navigating event? Maybe put a break there and then step through to see when it goes to zero.
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By Andria Jensen - 8/27/2007
Actually, by the time it gets into the Navigating event Clients.Count is already zero. It is 353 in the PrimaryBO_CurrentDataTableRefilled handler, but then when it goes to the PrimaryBO_Navigating event where I would expect to change where Clients is pointing, the count is back to zero. I'm just not sure what's happening here...any other ideas anyone?
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By StrataFrame Team - 8/28/2007
You might check the CurrentDataTable.Rows.Count and Filter properties to make sure that the records are not being filtered out. Since the business object navigates off of the CurrentView, it might be that the records are still there, but just not visible for some reason.
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By Andria Jensen - 8/28/2007
The CurrentDataTable.Rows.Count corresponds to Clients.Count....both are correct when in the PrimaryBO_CurrentDataTableRefilled handler, but when it gets to the PrimaryBO_Navigating event handler, the counts are zero and there is not a Filter set, it is "". I looked at the BusinessLayer code here and there wasn't much going on between these events that I could see. I also don't handle any events for Clients and it is a private object so it's not messed with anywhere else either. I will continue looking, but I can't see anywhere I am filtering the rows or refilling the table.
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By StrataFrame Team - 8/28/2007
Hrm... you could try putting a handler on the CurrentDataTableRefilled event of the child business object and put a break point in it. Then look at the CallStack window and see what called the refill further up the line.
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By Andria Jensen - 8/28/2007
I actually have breaks in Clients_CurrentDataTableRefilled, Navigating, and Navigated. None of these are hit in between the primary BO events I talked about. They are hit before that and the values are correct at that point, but between the CurrentDataTableRefilled and Navigating of the primary BO the row count value changes.
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By StrataFrame Team - 8/28/2007
If you have the SF source code built in debug, you can put a breakpoint in the BusinessLayer.vb file somewhere around 2109 or 2110 which should be the ChangeCurrentDataTable() method. It should get hit when the table is refilled or cleared (when a Clear() is called). You might give that a try...
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By Andria Jensen - 8/28/2007
Ok, one thing I think I did leave out was that the primary BO is used in a BusinessBindingSource to display in a DevExpress TreeList. I mention that now because the Clients.Count seems to change somewhere in the following code. Is there anything in here that could be causing something to fire off somewhere else I'm not aware of??Private Sub BusinessObject_CurrentDataTableRefilled() '-- Remove the handler on the old current view
RemoveHandler _BusinessObject_CurrentView.ListChanged, AddressOf BusinessObject_CurrentView_ListChanged '-- Save a reference to the new view
Me._BusinessObject_CurrentView = Me._BusinessObject.CurrentView '-- Add the handler to the new view
AddHandler Me._BusinessObject_CurrentView.ListChanged, AddressOf BusinessObject_CurrentView_ListChanged '-- Raise the list changed event
Me.OnListChanged(New ListChangedEventArgs(ListChangedType.Reset, -1))
End Sub
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By Andria Jensen - 8/28/2007
Ok, I have a little more information I'm not sure what to make out of. When it raises the ListChanged event in the BusinessBindingSource code like this:Protected Overridable Sub OnListChanged(ByVal e As ListChangedEventArgs)
RaiseEvent ListChanged(Me, e)
End SubI set a break at the raiseevent and step, but before it comes back from the event it hits the break in the Primary BO's Navigating event and my Clients.Count is back to zero. Before the ListChanged event is raised the Clients.Count is correct. Is this a DevExpress thing or is this an issue with how the BindingSource is interacting with it or do you have any idea what's going on here?
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By StrataFrame Team - 8/29/2007
Aha, using a BBS does make a difference. Basically, the business object tries to act like a single record, but it has several records inside of it. So, to make it work with the BBS (which expects a list of objects and a different reference for each object within the list, not just the same object over and over again), we have to create a new instance of the BO, share it's data table with the BO you selected as the BusinessObject for the BBS & set it to the right record, and return that new instance of the BO for each index of an item in the list. So, the problem is that your root business object that contains the populated child reference is not the actual business object being used by the BBS. That business object is a different instance of the same business object type and shares its CurrentDataTable with the root business object (they have the same reference), and it has its own internal child business object that isn't populated.Your best bet would be to change the child business object to a shared variable so that all instances of your primary BO type have the same reference. Or, you could possibly add the code to populate the child into the Navigated() event of the business object and only bring in the records that match the current primary bo record, but that would greatly increase the number of database queries if you have a lot of parent bo records. Or, you could move the child business object outside of the parent business object and reference it there.
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By Charles R Hankey - 8/29/2007
Pardon me for jumping in on this but as a complete .net newbie threads like this raise some 'best practices' questions that occur to me frequently in my transition from a world of VFP remote views.In the scenario described wouldn't you be bring a lot less data over the wire by pulling the lookup client info as part of a select statement that fills the primary cursor? ( and avoid a lot of the other hassles inherent in what is basically a related table model) If there are 10000 clients does the scenario described envision bringing 10000 records over the wire so the the 5 or 50 records in the primary dataset know the client description based on clientkey? It seems pulling a lot of records and then setting a filter based on the parentkey would be pretty intensive on the wire. I guess what I'm asking is do issues of network traffic etc behave differently in the .NET/Strataframe world than what I'm used to in running VFP apps against SQL Server with remote views ( in Visual FoxExpress ) TIA Charles
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