Resolving datasource object type on bands

Comments

• danni Denmark

  November 2011 edited November 2011

  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

  November 2011 edited 12:28AM

  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 Denmark

  November 2011 edited November 2011

  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;
          }
      }