CODEWITHSUNDEEP
vb.netado.net
Pradeep Kumar
Pradeep Kumar

Reputation: 6969

ADO.NET - Accessing Each DataView in DataViewManager

Looks like a silly question, but I can't find a way to access the DataViews in my DataViewManager. I can see it in the DataViewManager Visualizer window, so there must be a way.

What am I doing wrong?

dvm = New DataViewManager(MyDS)      ''-- MyDS is a strongly typed dataset
dvm.CreateDataView(MyDS.Company)
dvm.CreateDataView(MyDS.Sites)

MsgBox(dvm.DataViewSettings.Count)   ''-- shows 7, even though I added only 2.

For Each view As DataView In dvm     ''-- Error!
    MsgBox(view.Table.TableName)
Next

I also observed that irrespective of how many DataViews I create, data the DataViewManager Visualizer shows all DataViews in my dataset. Why?

enter image description here

Upvotes: 0

Views: 171

Answers (1)

Caius Jard
Caius Jard

Reputation: 74605

how do I hide those rows in parent whose child data view returns 0 rows after applying RowFilter on child

I've done it like this, but it feels like a nasty hack; I've never read the source deeply enough to know if there is a better way:

  • Add a column to your child datatable: Name: IsShowing, Type: Int, Expression: 1, ReadOnly: True
  • Put the following code:
        ChildBindingSource.RemoveFilter()
        ParentBindingSource.RemoveFilter()

        YourDataSet.ChildDataTable.IsShowingColumn.Expression = ""
        YourDataSet.ChildDataTable.Expression = $"IIF([SomeColumn] Like '{SomeFilterText}',1,0)"

        ChildBindingSource.Filter = "[IsShowing] > 0"
        ParentBindingSource.Filter = "Sum(Child.IsShowing) > 0"

The removal and re-add triggers a re-evaluation of the expression and the filters. There is probably a way to do this without removing/re-adding but I haven't yet found it.. Expressions are normally only re-evaluated when row data changes; changing an expression doesn't seem to recalculate all the row values/trigger a refresh of the relations and BS filters

It would be great if the parent filter supported complex expressions like SUM(IIF(Child.SomeColumn = 'SomeFilter',1,0)>0 but the SUM operator expects only a column name in the parent or child. As such, the circuitous route of having a column with an Expression be the part inside the SUM is the only way i've found to leverage the built in filtering

Remember when you test that the search is case sensitive. If you want it not to be you might have to have another column of data that is the lowercase version of what you want to search and lowercase your query string

Upvotes: 1

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