My question:
Somehow I am able to save a corrupt dataset to an xml file. With corrupt I mean a dataset that does not enforce its constraints. How do I correctly enforce it?

What did I do?
I created a dataset with constraints on it. The constraint was to enforce a maximum length on a column.
I created a form with a splitter, where I could select a record in a listbox on the left and edit the selected recordon the right inedit boxes.
I added a save button. Where I called
if(Validate())
{
dataSet.WriteToXml("FileName.xml");
}

My problem:
If I load data, change a record with an incorrect value and press the save button, it saves an incorrect dataset to file. If I load the file, only then it gives an error. Somehow I must perform a call that checks the constraints. Which call should do that?

Hi Edsger,

This sounds similar to a problem I see asked abouta lot and one I just answered in another post a few mintues ago.

Data in a DataRow has several different versions. First, there's the original version. Then, when it's being edited, it has a Proposed version and once it's done being edited, that becomes the Current version. Sometimes when editing, the row is left in the Proposed state and the Edit needs to be ended programmatically.

I think this might be your problem. Here's a method I *always* call before I attempt to check for .HasChanges() before saving data:

protected virtual void CommitProposedChanges(DataSet ds)
{
	if (ds == null)
		return;

	for (int nTable = 0; nTable < ds.Tables.Count; nTable++)
	{
		for (int nRow = 0; nRow < ds.Tables[nTable].Rows.Count; nRow++)
		{
			if (ds.Tables[nTable].Rows[nRow].HasVersion(DataRowVersion.Proposed))
			{
				ds.Tables[nTable].Rows[nRow].EndEdit();
			}
		}
	}
}

Do you have the DataSet.EnforceConstraints property set to True?

Hope this helps.

Hi Edsger,

This sounds similar to a problem I see asked abouta lot and one I just answered in another post a few mintues ago.

Data in a DataRow has several different versions. First, there's the original version. Then, when it's being edited, it has a Proposed version and once it's done being edited, that becomes the Current version. Sometimes when editing, the row is left in the Proposed state and the Edit needs to be ended programmatically.

I think this might be your problem. Here's a method I *always* call before I attempt to check for .HasChanges() before saving data:

protected virtual void CommitProposedChanges(DataSet ds)
{
	if (ds == null)
		return;

	for (int nTable = 0; nTable < ds.Tables.Count; nTable++)
	{
		for (int nRow = 0; nRow < ds.Tables[nTable].Rows.Count; nRow++)
		{
			if (ds.Tables[nTable].Rows[nRow].HasVersion(DataRowVersion.Proposed))
			{
				ds.Tables[nTable].Rows[nRow].EndEdit();
			}
		}
	}
}