StrataFrame Forum

Access ComboBox internal data values

http://forum.strataframe.net/Topic19535.aspx

By Edhy Rijo - 9/18/2008

When using a ComboBox to select a lookup value, sometimes, you need to update more than one field in the form with values from the lookup.

Is there a way to access the values of the data in the Internal Combobox BO? or should we just use the PK field returned by the BindingField to look for the data again manually?

By Aaron Young - 9/18/2008

If the values you want to update are listed in the combobox, you should be able to access them through the combobox's Items collection. SelectedIndex will give you a pointer to the current item in the list.
By Edhy Rijo - 9/19/2008

Thanks Aaron,

I will try that.  I know i can create an Escalar method to get the value, but since the data is already in the combo, I don't want to do another trip to the data to get the same value.

By Greg McGuffey - 9/19/2008

Another idea might be to use a form level BO that would hold the data needed to both fill the combo and to also provide the values for your other needs. You'd then fill the BO at the appropriate time and use CopyDataFrom method to fill the combo. This would allow you to put only the data needed in the combo for display but still have any data required (in the BO) for other uses. When the user selects a value, you'd just SeekToPrimaryKey to get the other values.



If I'm remembering this correctly, if the combo is filled via a BO method, then the items are DataRowView objects, with just two columns, display and value. You could probably figure out how to parse a multi-column combo, but seems like a lot of work when you could just be using a single BO to fill the combo and get the other values you need. In any case, this is what I've done in similar situations.



Hope that helps!
By Edhy Rijo - 9/19/2008

Hi Greg,

Thanks, it does make sense, even though it would be nice to have access to the internal BO used by the combobox to get other columns values.

By Greg McGuffey - 9/19/2008

If I recall correctly, that BO is created and destroyed during the fill. It isn't persisted at all. However, that is the beauty of the CopyDataFrom method, when you need to persist the data for other reasons! BigGrin
By Edhy Rijo - 9/21/2008

Greg McGuffey (09/19/2008)
If I recall correctly, that BO is created and destroyed during the fill. It isn't persisted at all. However, that is the beauty of the CopyDataFrom method, when you need to persist the data for other reasons! BigGrin

Hi Greg,

I finally had the chance to play with this, even though I have done this a lot of time with the listviews and like you said, it does work nicely, but it would do a very good enhancement to get access to the internal combobox BO. 

Anyway here is the code I am using from the 2 comboboxes to illustrate this functionality:

Private Sub cboItemType_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboItemType.SelectedIndexChanged
     '-- Filter the cboItemName combobox data with the following parameters:
     ' Pass the PrimaryBO EditingState to filter out Active records if needed.
     ' The name of the Inactive Status field
     ' The ItemType value
     ' And the Appliance used.
     Me.BizItems_Lookup.Clear()
     Me.BizItems_Lookup.FillByActiveRecords(Me.bizSC_AppliancesItems1.EditingState, "ItemIsInactive", Me.bizSC_AppliancesItems1.ItemType, Me.BizSC_Appliances1.FK_Appliances)
     Me.cboItemName.Requery()
End Sub
 
Private Sub cboItemName_ListPopulating(ByVal e As MicroFour.StrataFrame.UI.ListPopulatingEventArgs) Handles cboItemName.ListPopulating
     e.Parameters(0).Value = Me.BizItems_Lookup
     e.Parameters(1).Value = MicroFour.StrataFrame.Business.BusinessCloneDataType.ClearAndFillFromDefaultView
End Sub
 
Private Sub cboItemName_DropDown(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboItemName.DropDown
     If bizSC_AppliancesItems1.Count > 0 Then
          Me.cboItemName.Requery()
     Else
          Me.cboItemName.Items.Clear()
     End If
End Sub
 
Private Sub cboItemName_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboItemName.SelectedIndexChanged
     If Me.BizItems_Lookup.Count > 0 Then
          If Me.BizItems_Lookup.SeekToPrimaryKey(Me.bizSC_AppliancesItems1.FK_Items) Then
               Me.bizSC_AppliancesItems1.ItemPrice = Me.BizItems_Lookup.ItemPrice
          End If
     End If
End Sub
By Trent L. Taylor - 9/22/2008

You don't need access to the internal BO.  The internal BO is dead and gone once the combo is loaded.  But you have everything that you need right there in the data source.  When the BO is created and comes back, it is just executing the fill, using the parms specified, and the settings a DataTable to the DataSource of the combo.  So if you want to get to the datatable, just do this:

CType(MyCombo.DataSource, DataTable).Item("MyField")
By Edhy Rijo - 9/22/2008

Trent L. Taylor (09/22/2008)
You don't need access to the internal BO.  The internal BO is dead and gone once the combo is loaded.  But you have everything that you need right there in the data source.  When the BO is created and comes back, it is just executing the fill, using the parms specified, and the settings a DataTable to the DataSource of the combo.  So if you want to get to the datatable, just do this:

CType(MyCombo.DataSource, DataTable).Item("MyField")

Hi Trent,

Thanks for the info, but when testing your code above, I got an error that there is not Item property.  I have tried several ways to get access to any of the field values in the combo, but none worked.

Could you  please post the correct syntax to reference the combo field values?

By Trent L. Taylor - 9/22/2008

Sorry I was going quickly and didn't totally flesh out the properties.  It is just a data table so it would look like this:

CType(MyCombo.DataSource, DataTable).Rows(MyCombo.SelectedIndex).Items("MyField")
By Edhy Rijo - 9/22/2008

I hate to keep coming back with this, but it is not finding any of the columns I setup in the combox.

CType(Me.cboItemName.DataSource, DataTable).Rows(Me.cboItemName.SelectedIndex).Item("ItemPrice")

Here is the DataTable which only shows 3 columns and the column I would like to see "ItemPrice" its value is in the DropDown column:

I already implemented the method of using another BO for lookup, but if this can work, then it will be easier to maintain and re-use in other forms.

By Trent L. Taylor - 9/22/2008

They won't be the name of the columns in the combo box.  There will be 2 different columns (just put a break point in your code and look at the columns).  There will be a display and a value column (I think) but it gives you the contents of the combo.  The BO that was used to generate the contents of the BO is long gone by this point, so if you want to get back to that you will have to manually populate your own combo.
By Edhy Rijo - 9/22/2008

Thanks!