DataSet does not support System.Nullable<> - frameworks

Question

i have an app which has btn to preview report made in crystal report. I added Dataset as datasource of the report and dragged datatable from the toolbox and added the fields I need as columns. I got the instruction from this link http://aspalliance.com/2049_Use_LINQ_to_Retrieve_Data_for_Your_Crystal_Reports.2. This is my 2nd report the first one works and did not encounter any prob at all that is why i am confused, not to mention it also has nullable column. the error says: DataSet does not support System.Nullable<>.
private void ShowReportView()
{
string reportFile = "JudgeInfoFMReport.rpt";
ObservableCollection<tblJudgeFileMaint> judgeFileMaintList;
judgeFileMaintList = GenerateReport();
if (judgeFileMaintList.Count > 0)
{
CrystalReportViewerUC crview2 = new CrystalReportViewerUC();
crview2.SetReportPathFile(reportFile, judgeFileMaintList);
crview2.ShowDialog();
}
else
{
System.Windows.MessageBox.Show("No record found.", module, MessageBoxButton.OK, MessageBoxImage.Information);
}
}
private ObservableCollection<tblJudgeFileMaint> GenerateReport()
{
var result = FileMaintenanceBusiness.Instance.GetAllJudgeInfoList();
return new ObservableCollection<tblJudgeFileMaint>(result);
}
The error is in the part where I set datasource report.SetDataSource
public bool SetReportPathFile(string reportPathFile, IEnumerable enumerable)
{
string reportFolder = #"\CrystalReportViewer\Reports\";
string filename = System.Windows.Forms.Application.StartupPath + reportFolder + reportPathFile; // "\\Reports\\CrystalReports\\DateWiseEmployeeInfoReport.rpt";
ReportPathFile = filename;
report.Load(ReportPathFile);
report.SetDataSource(enumerable);
report.SetDatabaseLogon("sa", "admin007");
bRet = true;
}
_IsLoaded = bRet;
return bRet;
}
I read some answers and says I should set the null value to DBNUll which I did in the properties window of each column if it is nullable. Can anyone help me please? thanks

Answer 1

Your question can be seen in this post, but in a generic way ... that way you can pass an Object to a DataSet typed!
.NET - Convert Generic Collection to DataTable

Answer 2

figured it out. by using a collectionextention, copied somewhere, I forgot the link. Os to whoever it is who made the class, credits to you.
class method looks like this.
public statis class CollectionExtension {
public static DataSet ToDataSet<T>(this IEnumerable<T> collection, string dataTableName)
{
if (collection == null)
{
throw new ArgumentNullException("collection");
}
if (string.IsNullOrEmpty(dataTableName))
{
throw new ArgumentNullException("dataTableName");
}
DataSet data = new DataSet("NewDataSet");
data.Tables.Add(FillDataTable(dataTableName, collection));
return data;
}
}
then you can use it by doing this in getting your source to your report:
private DataSet GenerateNeutralContEducReport(string dsName)
{
var contEduHistoryList = FileMaintenanceBusiness.Instance.GetManyNeutralFMContEducHistoryInfobyKeyword(CurrentNeutralFM.NeutralID, "NeutralID").ToList();
return CollectionExtensions.ToDataSet<tblContinuingEducationHistory>(contEduHistoryList, dsName);
}

Answer 3

I found little help from the other proposed answers but this solution worked.
A different way to solve this problem is to make the data column nullable.
DataColumn column = new DataColumn("column", Type.GetType("System.Int32"));
column.AllowDBNull = true;
dataTable.Columns.Add(column);
https://learn.microsoft.com/en-us/dotnet/api/system.data.datacolumn.allowdbnull?view=netcore-3.1

Answer 4

foreach (PropertyDescriptor property in properties)
{
dt.Columns.Add(property.Name, Nullable.GetUnderlyingType(property.PropertyType) ?? property.PropertyType);
}