IT and business subjects
09-Feb-1212 Leave a comment
ERROR
Windows Forms DataBinding displays ‘System.Data.DataRowView’ in text boxes and other controls
SOLVED
Was a ComboBox databinding pointing at a field no longer in the dataset.
15-Nov-1111 Leave a comment
Entity Framework looks useful and I have limited use of it in my code. Also several developers have expressed to me how they have found it useful.
I currently use a lot of WinForms databinding using DataSets and BindingSource. Out of the box I get column header sorting. Also it is a simple matter to set BindingSource.Filter and BindingSource.Sort as strings. I have used this feature to provide a lot of data-driven filter and sort strings for UI quick filter and sort which works very well.
However when I use Entity Framework the column header sort and BiningSource.Filter and .Sort properties do not work. My understanding is that this is because EF does not support IBindingListView. Although it might but not out of the box. Please advise or consider implementing this in future editions of Entity Framework.
Thank you
Stephen, UK
06-Jul-1111 Leave a comment
Dim context As New SOPEntities
System.Data.Entity.DbExtensions.Load(context.Employees.Where(Function(f) f.Current = True).OrderBy(Function(g) g.FullName))
EmployeeBindingSource.DataSource = context.Employees.Local
ListBox1.DataSource = System.Data.Entity.DbExtensions.Tobindinglist(context.Employees.Local)
ListBox1.DisplayMember = “FullName”
Problem
‘local’ is not a member of ‘System.Data.Objects.ObjectSet(Of <entityname>)’
Solved
Open the <Name>Model.edmx > Right click > Add code generation item…
Choose ADO.Net DbContext Generator. This has affect of changing the .edmx file Code Generation Strategy to “None” and creates a text template model and .Local now works.
Uses EF4.1 EntityFramework.dll
Database first, then add code generation item to get T4 simpler classes and DBSet inherits DBContext
Initially could not work out how to get the Load method. See above for solution.
There is no MSDN VB.Net sample yet. The C# is more like context.Employees.Local.ToBindingList. So it took me a while to work out the syntax above.
Unsolved:
Also the FullName is now a computed column in the database. Was unable to work out how to do this in EF. It may come in the future as a “Model Defined Function”. Do not think this is a Scalar or Complex Type which is something else.
Unsolved:
For BindingSource to support complex filter it needs to support IBindingListView. Typically EF does not.
Binding Objects to Controls
http://msdn.microsoft.com/en-us/library/gg197521(v=VS.103).aspx
Following is in C#
http://msdn.microsoft.com/en-us/library/gg197523(v=VS.103).aspx
24-Apr-1111 Leave a comment
Use Object.Equals.
Then set the combobox selecteditem to a new instance of the object with the required ID or other.
Sample Equals
Public Overrides Function Equals(obj As Object) As Boolean
If obj Is Nothing Then
Return False
End If
Return CType(obj, Customer).ID = Me.ID
End Function
23-Apr-1111 Leave a comment
Window form and control properties may be bound to Application Settings, by expanding the Application Settings at the top of the control properties.
This works fine, for say BackColor. However be warned, there is then a marker by the related bound property. If you then set this manually, this is actually bi-directional and you will change it in the Settings file at the same time, and hence all accross your application, which is probably not your intended action.
See Microsoft Book 70-505 Windows Forms p 587
10-Nov-1010 Leave a comment
Position is important. Needs to be before EndEdit
Me.TimeSheetBindingSource.EndEdit
If Me.TimeEndDateTimePicker.Checked = False Then
rowTS = CType(CType(Me.TimeSheetBindingSource.Current, DataRowView).Row, dsMyCo.TimeSheetRow)
rowTS.SetTimeEndNull()
End
11-Nov-0909 Leave a comment
PrivateSub frm_VisibleChanged(sender AsObject, e As System.EventArgs) HandlesMe.VisibleChanged
If Me.Visible Then
‘ToolStrip1.TabStop = True
ActiveControl = InputProductToolStripTextBox.Control
End If
EndSub
Stephen Shakespeare 