EnsureValidSortExpression method

carewithl · December 15th, 2009, 03:51 PM

hi

The following questions all refer to the EnsureValidSortExpression method ( page 397 ):

a) I assume the reason we replace substring âtitleâ with âtbh_posts.titleâ is so that SQL server processing our query doesnât get confused whether we are referring to tbh_Forums.Title or to tbh_Post.Title column:

Code:

         if (sortExpr.StartsWith("title"))
              sortExpr = sortExpr.Replace("title", "tbh_posts.title");

b) For each of the GridViewâs columns that enable sorting, EnsureValidSortExpression method checks whether supplied sortExpression parameter equals to one of three kinds of strings Ã âcolumn_nameâ or âcolumn_name descâ or âcolumn_name ascâ. GridView automatically appends âASC" or âDESCâ to a âcolumn_nameâ, so I donât see the point in EnsureValidSortExpression also checking whether supplied parameter equals to âcolumn_nameâ type of string, since as far as I know, sortExpression string will always also contain âASCâ or âDESCâ value?! Thus, wouldnât the following code be just as efficient:

Code:

      protected virtual string EnsureValidSortExpression(string sortExpression)
        { 
  ... 
   
  if (!sortExpr.Equals("lastpostdate asc") && !sortExpr.Equals("lastpostdate desc") &&
              !sortExpr.Equals("viewcount asc") && !sortExpr.Equals("viewcount desc") &&
              !sortExpr.Equals("replycount asc") && !sortExpr.Equals("replycount desc") &&
              !sortExpr.Equals("addeddate asc") && !sortExpr.Equals("addeddate desc") &&
              !sortExpr.Equals("addedby asc") && !sortExpr.Equals("addedby desc") &&
              !sortExpr.Equals("title asc") && !sortExpr.Equals("title desc") &&
              !sortExpr.Equals("lastpostby asc") && !sortExpr.Equals("lastpostby desc"))
           {
              sortExpr = "lastpostdate desc";
           }
   
  ...

thanx