ObjectDataSource : Manually controlling the sorting expression.

By default the GenWise ASP.NET Templates uses the object datasource SortParamterName. When that property is used , the objectdatasource will manipulate internally the sort expression (change to asc , desc) .

  269     ObjectDataSource runat="server" ID="ObjectDataSource1" TypeName="BOLayer.CustomerFactory"

  270                 SelectCountMethod="Count" EnablePaging="True" UpdateMethod="Save" DeleteMethod="Delete"

  271                 SortParameterName="pSortExpression" MaximumRowsParameterName="pMaxResult" StartRowIndexParameterName="pFirstResult"

  272                 SelectMethod="GetAll">

  273                 

  274                     Parameter Name="pSortExpression">Parameter>

  275                     Parameter Name="pCriteria">Parameter>

  276                 

  277                 

  278                     Parameter Name="CustomerID">Parameter>

  279                 

  280             ObjectDataSource>

For more advanced sorting scenarios you might want to manually control what's passed to the pSortExpression method parameter. This can be done in the following way :

Subscribe to the ObjectDataSource Selecting method (genwise does that automatically)

   44 ObjectDataSource1.Selecting += new ObjectDataSourceSelectingEventHandler(ObjectDataSource1_Selecting);

  253    protected void ObjectDataSource1_Selecting(object pSender, ObjectDataSourceSelectingEventArgs pEventArgs)

  254         {

  255             if (pEventArgs.ExecutingSelectCount)

  256                 pEventArgs.InputParameters.Remove("pSortExpression");

  257             else

  258                 pEventArgs.InputParameters["pSortExpression"] = _newSortExpression;

  259 

  260             pEventArgs.InputParameters["pCriteria"] = Browse1_GetCriteria();

  261         }

Where does _newSortExpression come from ? 

  198         string _newSortExpression = null;

  199         protected void Browse1_Sorting(object pSender, GridViewSortEventArgs pEventArgs)

  200         {

  201             // Calls this method to adapt the sort syntax (required for Composite sorting).

  202             _newSortExpression = WebUtils.SortExpressionTransformer(pEventArgs);

  203             pEventArgs.Cancel = true;

  204         }

SortExpression Tranformer takes the ObjectDataSource parameters and manipulates them to make them compatible with the GenWise Factories sorting syntax.

Below is the code of this method:

   63   public static string SortExpressionTransformer(GridViewSortEventArgs pEventArgs)

   64     {

   65         if (pEventArgs == null) throw new ArgumentNullException("pEventArgs");

   66 

   67         if (pEventArgs.SortDirection == SortDirection.Ascending)

   68         {

   69             return pEventArgs.SortExpression;

   70         }

   71 

   72         string newSortExpression = pEventArgs.SortExpression;

   73         string DESC = " DESC";

   74 

   75         if (pEventArgs.SortDirection == SortDirection.Descending)

   76         {

   77             if (pEventArgs.SortExpression.Contains(","))

   78             {

   79                 // Case : We have a composite sorting ( Field1,Field2) 

   80                 newSortExpression = string.Empty;

   81                 string[] sortParts = pEventArgs.SortExpression.Split(',');

   82                 for (int i = 0; i <> 
   83                 {
 
   84                     string sortPart = sortParts[i];
 
   85 
 
   86                     int sortDirectionIndex = sortPart.IndexOf(DESC);
 
   87                     bool isDescending = (sortDirectionIndex > -1);
 
   88 
 
   89                     string property = sortPart;
 
   90                     if (isDescending)
 
   91                     {
 
   92                         // sta : udpate templates.
 
   93                         //property = sortPart.Substring(0, (sortPart.Length - sortDirectionIndex + 1));
 
   94                         property = sortPart.Substring(0, (sortPart.Length - sortDirectionIndex + 1 + DESC.Length));
 
   95                     }
 
   96 
 
   97                     if (i > 0) newSortExpression += ",";
 
   98                     newSortExpression += property;
 
   99 
 
  100                     // Only add the DESC to all except the last (Last one will be controlled automatically by the object datasource.
 
  101                     if (!isDescending)
 
  102                     {
 
  103                         if (i < (sortParts.Length - 1))
 
  104                             newSortExpression +=  DESC ;
 
  105                     }
 
  106                 }
 
  107                 pEventArgs.SortExpression = newSortExpression;
 
  108             }
 
  109         }
 
  110         return newSortExpression;
 
  111     }