Problem inserting a row in a DataTable

[Ana]

Hi,

I have two DataTables (dTable and childrenTable) and I need to insert
one row from childrenTable to dTable in a specific position. My code
is like this:

For Each row In childrenTable.Rows
Dim newRow As DataRow = row
dTable.Rows.InsertAt(newRow, indexInsert)
indexInsert = indexInsert + 1
Next

However, I'm having the error: "This row already belongs to another
table". Any ideas about how to solve this problem?

Thanks in advance,

Ana

[Ana]

Never mind. I added the values for each column and now it works.

For Each row In childrenTable.Rows

Dim newRow As DataRow = dTable.NewRow
newRow("Id") = row("Id")
newRow("Name") = row("Name")

dTable.Rows.InsertAt(newRow, indexInsert)
indexInsert = indexInsert + 1
Next

[Cerebrus]

This is not the correct way. What you are doing in this method is to
create a new Row instance and populate its values, instead of
inserting the existing DataRow instance from the child table. Your
code will become unmanageable if the no. of columns increases.

IMO, the correct way to do this would probably be to use the
DataTable.ImportRow() method (and then the DataRowCollection.InsertAt
() method). I'm just relying on memory here, so I may be mistaken
about the exact implementation.

[Ana]

I thought of using the ImportRow() method, but I gave up of the idea
because I needed to insert the Row in a specific position in the
Table. How can I do this using the ImportRow()?

Thanks,

Ana

[Cerebrus]

Hmmm... I found a little time to check it out and it turns out that I
was mistaken. Contrary to my initial assumption, ImportRow() does
actually *insert* the DataRow at the last index position in the Table.
I was probably confusing it with the way that the
XmlDocument.ImportNode() works.

So, the solution in your case will have to involve creation of a new
DataRow. What can be optimized however is the copying of individual
DataColumns. Here's a sample function I wrote to do this:

---
Private Sub ImportRows(ByVal srcTable As DataTable, ByVal tgtTable As
DataTable, ByVal insertPos As Integer)
For Each srcDR As DataRow In srcTable.Rows
Dim tgtDR As DataRow = tgtTable.NewRow()
tgtDR.ItemArray = srcDR.ItemArray
tgtTable.Rows.InsertAt(tgtDR, insertPos)
insertPos += 1
Next
End Sub
---

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