How to filter a dataset in a For...Each loop?

[Agent707]

I have a dataset with a column "KeyName". I need to filter my for each loop on this if I can.

For Each oDataRow In oDataSet.Tables(0).Rows
   'code
Next

Something like this...

e.g.

For Each oDataRow In oDataSet.Tables(0).Rows (where "KeyName = 'SomeValue'")
   'code
Next

The reason I need to do this is THIS For Each loop is nested inside another one where I am looping though each "KeyName" in an XML Document.

Looks like this.

For Each lo_node In lo_nodeSet.SelectNodes("attachments")
   lo_attachments = GetDataElement(lo_node, "attachments")
   ls_name = lo_attachments.GetAttribute("KeyName")
   'some code
   For Each oDataRow In oDataSet.Tables(0).Rows (where KeyName = ls_name)
       'BUNCH of code
   Next 
   'more code
Next

Hope that makes sense. Thanks

[PlausiblyDamp]

Could you not use a DataView to filter the DataTable to the values you need and then loop through those rows rather than doing the filtering yourself as part of the loop?

[Agent707]

My post count reflects my experience with .Net. :D This is my first attempt at a .net app using a database, so my knowledge on these datasets...etc. is kind of limited.

 

But what you say sounds good. After messing with it a bit. I came up with this.

oDataView = oDataTable.DefaultView
For Each lo_node In lo_nodeSet.SelectNodes("attachments")
   lo_attachments = GetDataElement(lo_node, "attachments")
   ls_name = lo_attachments.GetAttribute("KeyName")
   oDataView.RowFileter = "name = '" & ls_name & "'"
   'some code
   For Each oDataRow In oDataView.Table.Rows
       'some code
   Next 
   'more code
Next

And works great. Thanks!

 

These .net data objects are starting to click a little bit now.

[FZelle]

This shouldn't work as expected.

You are ignoring the view with oDataView.Table.Rows.

You have to use

oDataView = oDataTable.DefaultView
For Each lo_node In lo_nodeSet.SelectNodes("attachments")
   lo_attachments = GetDataElement(lo_node, "attachments")
   ls_name = lo_attachments.GetAttribute("KeyName")
   oDataView.RowFileter = "name = '" & ls_name & "'"
   'some code
   For Each oDataRowView In oDataView
       'some code
   Next 
   'more code
Next 

[Agent707]

I don't see why you say "This shouldn't work"...? :confused:

 

A Dataview object has a Table (DataTable) object, which has a Rows (DataRowCollection) object... It's a simple loop through the rows collection.

 

And it works perfectly.

[FZelle]

The Table in DataView is the unfiltered Table.

So you are not looping through the filtered values.

 

Easier for your purpose would be the DataTable.Select() funktion.