Your combo cboGenre should be bound to the SelectedValue instead of the
SelectedItem. As an aside, note that
ideally, you would not need to convert your genre_id in the database. This
should be an integer value. Also, release and re-bind is resource-intensive.
"Steve S" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>I am having a problem with getting a bound combobox to display the
> correct value. I'm hoping someone can point out where I've gone wrong.
>
> The scenario is a main table of Quotations by Author (Aristotle,
> Einstein, Will Rogers, Yogi Berra, etc.) and a foreign key for the
> quotation's Genre. The look up table, "Genre" has 2 columns Genre and
> Genre_id. The data in the look up table looks like:
> Genre_id Genre
> 0 Undefined (This is the default for the foreign key in the
> main table)
> 1 Humorous
> 2 Insightful
> 3 Inspirational
> etc.
>
> I have set many of the qutations' foreign key to the appropriate
> genre_id but most are the default of 0 for undefined.
>
> I've loaded a treeview with quotation Authors. Selecting the Author
> loads a dataset with the authors quotations that is then bound to a
> datagrid. Selecting the quotation in the grid loads bound text fields
> for editing and should position the combobox to the Genre for the
> quotation. Key here is should. This is where I seem to have lost it
> and am asking for help.
>
> The grid style contains the foreign key as well as the other fields I
> want to edit. The combobox is loaded with all the Genre records just
> not showing the correct genre for the record selected in the grid; it
> always shows the first record. I am able to force the correct combobox
> display but not when bound
>
> Here is the pertinent code:
>
> Dim cn As New SqlCeConnection(LocalCnxStr)
> Dim cmd as SqlCeCommand
> dim da as new SqlCeDataAdapter
> dim cell as new DataGridCell
>
> if isnothing (dsQ) then
> dsq = new DataSet
> '// first time thru set the select command for the look up
> data
> cmd = New SqlCeCommand("Select genre as Genre, " & _
> "convert (nvarchar,genre_id) as
> Genre_id " & _
> "from genre ",cn)
> da.SelectCommand = cmd
> da.Fill(dsQ,"Genre") '// first table(0)
>
> '// then load the look up cbo
> cboGenre.DataSource = dsq.Tables("Genre")
> cboGenre.DisplayMember = "Genre"
> cboGenre.ValueMember = "Genre_id"
>
> else '// clear records in 2nd data table
> '// from previous selection
> '//cboGenre.SelectedIndex = -1
> 'dsq.Relations.Clear
> dsq.Tables("AQuotes").Clear
> dgQuotes.TableStyles.Clear '// clear the grid style
>
> '//unBindQuotes '// unbind the editor fields
> txtAuthor.DataBindings.Clear
> txtQuote.DataBindings.Clear
> txtContext.DataBindings.Clear
> lblguid.DataBindings.Clear
> cboGenre.DataBindings.Clear
>
> end if
>
> '// set the parameter value with the selected tree node
> daAuthor.SelectCommand.Parameters.Item(0).Value =
> trvwQ.SelectedNode.Text
>
> '// fill the dataset with the 2nd named table
> '// daAuthor commands set in InitAuthorAdapter
> daAuthor.Fill(dsQ,"AQuotes") '// 2nd table(1)
>
> '// relation doens't appear to have any affect with
> '// binding foreign key to combo box
>
> 'dsq.Relations.Add("QuoteGenre",dsq.Tables("AQuotes").Columns("Genre_id"),
> _
> '
> dsq.Tables("Genre").Columns("Genre_id"),False)
> '// setting constraint to true genereates error
> '// as not all records in parent use all look up table
> records
> '// need all look up records to change Genre for selected
> record
>
> '// bind the grid to the table
> dgQuotes.DataSource = dsQ.Tables("AQuotes")
> '//BindQuotes '// bind the editor fields
> txtAuthor.DataBindings.Add("Text", dgQuotes.datasource,
> "Author")
> txtQuote.DataBindings.Add("Text", dgQuotes.datasource,
> "Quote")
> txtContext.DataBindings.Add("Text", dgQuotes.datasource,
> "Context")
> lblguid.DataBindings.Add("Text", dgQuotes.DataSource,
> "quote_id")
>
> '// Bind cbo to foreign key in grid
> '// doesn't seem to work
> cboGenre.DataBindings.Add("SelectedItem",
> dgQuotes.DataSource, "Genre_id")
>
> '// grid style includes fk and all fields for editing
> QgridStyle '// set the grid style
>
> '// not able to get the cbo binding working correctly
> '// so force the current cell changed event to fire
> '// and set the cbo selected index appropriately there
> 'cell = dgquotes.CurrentCell
> 'dgquotes.CurrentCell = new DataGridCell(0,1)
> 'dgquotes.CurrentCell = cell
>
> '// code from grid cellchanged event
> 'dim dg as new DataGrid
> 'dg = sender
> '// this is bad coding since the item index and the key
> '//are assumed to be the same
> '// may not always be the case
> '// should use for each loop instead - slower
> 'cboGenre.SelectedIndex = dg.item(dg.CurrentCell.RowNumber,3)
>
>
> Any and all assistance in resolving this will be appreciated.
>
> Steve
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