Unable to cast object of type 'System.DBNull' to type 'System.String'

c#, datarow, datatable, string

Solution

Try this:

foreach (object str in row.ItemArray) 
{ 
    if (DbNull.Value.Equals(str))
       sb.Append("NULL");
    else
       sb.Append(str.ToString()); 
}

Problem

I have a datable code to generate a string, which is sb.ToString(). ``` DataTable dt = dbaccess.GetDataTable("TEST"); // get datatable List<DataRow> drlist = dt.AsEnumerable().ToList(); // each row only has one element. StringBuilder sb = new StringBuilder(); foreach (DataRow row in drlist) { foreach (string str in row.ItemArray) { sb.Append(str); } } ``` The datatable is ``` NULL 0 138 337 1666 1680 2511 8113 ``` You see that there is "NULL" to cause the error "Unable to cast object of type 'System.DBNull' to type 'System.String'. How to fix it?

Original source

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