Resolving datasource object type on bands

danni

hi

I use the current method to discover the type of datasource on bands:

private List<String> ResolveDataSources(Report report)
        {
              List<String> list = new List<String>();

              foreach (PageBase pb in report.Pages)
              {
                  
                  foreach (var obj in pb.AllObjects)
                  {
                      if (obj is FastReport.DataBand)
                      {
                          if ((obj as FastReport.DataBand).DataSource != null &&
                              (obj as FastReport.DataBand).DataSource.DataType != null)
                              list.Add((obj as FastReport.DataBand).DataSource.DataType.GetGenericArguments()[0].Name);
                      }

                  }
              }
            return list;
        }

Can you tell me why this does not work before datasource is set?

I use the list<string> of types to determin shich data should be loaded for the report.

Thanks.

danni

A report saved as a blob/text to my database contains a datatype. But when I load it into Fastreport.Report object it is null.

Can this be correct? (I can see the type after data is registered, but then it is too late)

I am missing the datatype value in order to minimize the number of calls to the database when I fetch data for the report.

AlexTZ

Hello,

This code works well for me if I insert in in the Features/Business Objects demo report:

    private void ResolveDataSources(Report report)
    {
      foreach (PageBase pb in report.Pages)
      {
        foreach (Base obj in pb.AllObjects)
        {
          if (obj is FastReport.DataBand)
          {
            if ((obj as FastReport.DataBand).DataSource != null &&
              (obj as FastReport.DataBand).DataSource.DataType != null)
              MessageBox.Show((obj as FastReport.DataBand).DataSource.DataType.GetGenericArguments()[0].Name);
          }

        }
      }
    }
    
    private void _StartReport(object sender, EventArgs e)
    {
      ResolveDataSources(Report);
    }

The _StartReport event handler is connected to the Report.StartReport.

danni

Hey Alex.

It seems start is fired when datasource is bound the first time? I would like to know the types before retrieving data from my server environment.


I have modified my example it a bit, so it works as I would like it to do.

It is a bit of a hack because I register an empty datasource, then resolve types from the bands.

Now I can reduce the Loading of data with the resolved types from the bands, Meaning I only fetch data needed to preview the report. Awsome!

public class ResolveDataSources<T> where T : BaseReportObject
    {
        private readonly Report _report;

        public ResolveDataSources(Report report)
        {
            _report = report;
        }

        public List<string> Resolve()
        {
            T item = (T)Activator.CreateInstance(typeof (T));
            new RegisterFastReportData<T>(_report, new List<T> {item}).RegisterData(); //registers a dummy datasource of the required type (T)

            return GetDataTypesOfBands(_report); //returns the Type used in datasources
        }

        private List<string> GetDataTypesOfBands(Report report)
        {
            List<string> list = new List<string>();

            foreach (PageBase pb in report.Pages)
            {
                foreach (DataBand databand in pb.AllObjects.OfType<DataBand>())
                {                    
                    if (databand.DataSource != null && databand.DataSource.DataType != null)
                        list.Add(databand.DataSource.DataType.GetGenericArguments()[0].Name);
                }
            }
            return list;
        }
    }