Field Truncation in a DataTable

15 Mar 2007 12:41 AM

MarcG

I have a dotnet 1.1 app that I am redeveloping in 2.0. Part of the work
involves replacing code that executed generated SQL commands against a
database with a dataset approach.

In the original system, if text field data was longer than the field size in
the table, the data was simply truncated. This turned out to be a fine result
(sorry).

Using datasets, when I call the
myDatatable.AddMyTypedDatarow(myTypedDatarow) method, I get an
ArgumentException with the message...

"Cannot set column 'label'. The value violates the MaxLength limit of this
column."

I can't find anything in the datatable designer that would let me specify
truncation, which would be my (ugly but) preferred approach.

Alternately, is there an event or more descriptive exception I can hook or
catch so that I can do the truncation myself? I REALLY don't want to have to
check each text field manually. The field data is being loaded from a file
produced by another app that is not concerned about text length.

Thx
Marc

15 Mar 2007 7:40 AM

Linda Liu [MSFT]

Hi Marc,

After doing some research, I found that we could handle the ColumnChanging
event of the DataTable to truncate the proposed value, if necessary.

The ColumnChanging event occurs when a value is being changed for the
specified DataColumn in a DataRow, even if the DataRow has not been added
to the DataTable.

The following is a sample.

public Form2()
{
            InitializeComponent();
            this.dataSet11.TestTable.ColumnChanging += new
DataColumnChangeEventHandler(TestTable_ColumnChanging);
}
void TestTable_ColumnChanging(object sender, DataColumnChangeEventArgs e)
{
            if (e.Column.ColumnName == "columnname")
            {
                e.ProposedValue = ((string)e.ProposedValue).Substring(0,
maxlengthofcolumn);
            }
}

Hope this helps.
If you have any question, please feel free to let me know.

Sincerely,
Linda Liu
Microsoft Online Community Support

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15 Mar 2007 1:36 PM

MarcG

Perfect Linda.

Thanks
Marc