DataSet不支持c#中的System.Nullable <>异常

Question

public partial class Form2 : Form
{
        public Form2()
        {
            InitializeComponent();
        }
        private void Form2_Load(object sender, EventArgs e)
        {
            RST_DBDataContext db = new RST_DBDataContext();
            var d = (from s in db.TblSpareParts
                                        select new {  s.SPartName, s.SPartCode, s.ModelID, s.SPartLocation,  s.SPartActive, s.SPartSalePrice }).ToArray();
            CrystalReport1 c = new CrystalReport1();
            c.SetDataSource(d);
            crystalReportViewer1.ReportSource = c;

        } 
}

我正在尝试在sql表中生成水晶报告SPartSalePrice因为在c.SetDataSource(d)上可以为空; 异常来请解决

Answer 1

Use the null coalescing or conditional operators in your anonymous projection to map out the null:

Coalescing:

var d = (from s in db.TblSpareParts
  select new 
  { 
    s.SPartName,
    ...,
    SPartSalePrice = s.SPartSalePrice ?? 0.0,
    ...
  }).ToArray();

Conditional (Not really useful for nulls, but useful for projecting other values)

  SPartSalePrice = s.SPartSalePrice == null ? 0.0 : s.SPartSalePrice,

The field needs to be given a name (I've kept the original one, SPartSalePrice), and the type of substitution (0.0) should match the type of the field.