Asp.net GridView multi-column sorting and sorting direction icon code

Asp tutorial. net GridView multi-column sorting and sorting direction icon code

Public class WebGridView: GridView
{
/**/
///
/// Whether to enable or disable multi-column sorting
///
[
Description ("whether to enable multi-column sorting "),
Category ("sort "),
DefaultValue ("false "),
]
Public bool AllowMultiColumnSorting
{
Get
{
Object o = ViewState ["EnableMultiColumnSorting"];
Return (o! = Null? (Bool) o: false );
}
Set
{
AllowSorting = true;
ViewState ["EnableMultiColumnSorting"] = value;
}
}
/**/
///
/// Icon displayed in ascending order
///
[
Description ("icon displayed in ascending order "),
Category ("sort "),
Editor ("System. Web. UI. Design. UrlEditor", typeof (System. Drawing. Design. UITypeEditor )),
DefaultValue (""),

]
Public string SortAscImageUrl
{
Get
{
Object o = ViewState ["SortImageAsc"];
Return (o! = Null? O. ToString ():"");
}
Set
{
ViewState ["SortImageAsc"] = value;
}
}
/**/
///
/// Icon displayed in descending order
///
[
Description ("show icons in descending order "),
Category ("sort "),
Editor ("System. Web. UI. Design. UrlEditor", typeof (System. Drawing. Design. UITypeEditor )),
DefaultValue (""),
]
Public string SortDescImageUrl
{
Get
{
Object o = ViewState ["SortImageDesc"];
Return (o! = Null? O. ToString ():"");
}
Set
{
ViewState ["SortImageDesc"] = value;
}
}
Protected override void OnSorting (GridViewSortEventArgs e)
{
If (AllowMultiColumnSorting)
{
E. SortExpression = GetSortExpression (e );
}

Base. OnSorting (e );
}
Protected override void OnRowCreated (GridViewRowEventArgs e)
{
If (e. Row. RowType = DataControlRowType. Header)
{
If (SortExpression! = String. Empty)
{
DisplaySortOrderImages (SortExpression, e. Row );
This. CreateRow (0, 0, DataControlRowType. EmptyDataRow, DataControlRowState. Normal );
}
}
Base. OnRowCreated (e );
}
/**/
///
/// Obtain the sort expression
///
Protected string GetSortExpression (GridViewSortEventArgs e)
{
String [] sortColumns = null;
String sortAttribute = SortExpression;

If (sortAttribute! = String. Empty)
{
SortColumns = sortAttribute. Split (",". ToCharArray ());
}
If (sortAttribute. IndexOf (e. SortExpression)> 0 | sortAttribute. StartsWith (e. SortExpression ))
{
SortAttribute = ModifySortExpression (sortColumns, e. SortExpression );
}
Else
{
SortAttribute + = String. Concat (",", e. SortExpression, "ASC ");
}
Return sortAttribute. TrimStart (",". ToCharArray (). TrimEnd (",". ToCharArray ());

}
/**/
///
/// Modify the sorting order
///
Protected string ModifySortExpression (string [] sortColumns, string sortExpression)
{
String ascSortExpression = String. Concat (sortExpression, "ASC ");
String descSortExpression = String. Concat (sortExpression, "DESC ");

For (int I = 0; I <sortColumns. Length; I ++)
{

If (ascSortExpression. Equals (sortColumns [I])
{
SortColumns [I] = descSortExpression;
}

Else if (descSortExpression. Equals (sortColumns [I])
{
Array. Clear (sortColumns, I, 1 );
}
}

Return String. Join (",", sortColumns). Replace (","). TrimStart (",". ToCharArray ());

}
/**/
///
/// Obtain the current expression to sort the selected columns
///
Protected void SearchSortExpression (string [] sortColumns, string sortColumn, out string sortOrder, out int sortOrderNo)
{
SortOrder = "";
SortOrderNo =-1;
For (int I = 0; I <sortColumns. Length; I ++)
{
If (sortColumns [I]. StartsWith (sortColumn ))
{
SortOrderNo = I + 1;
If (AllowMultiColumnSorting)
{
SortOrder = sortColumns [I]. Substring (sortColumn. Length). Trim ();
}
Else
{
SortOrder = (SortDirection = SortDirection. Ascending )? "ASC": "DESC ");
}
}
}
}
/**/
///
/// Draw an image in ascending and descending order
///
Protected void DisplaySortOrderImages (string sortExpression, GridViewRow dgItem)
{
String [] sortColumns = sortExpression. Split (",". ToCharArray ());

For (int I = 0; I <dgItem. Cells. Count; I ++)
{
If (dgItem. Cells [I]. Controls. Count> 0 & dgItem. Cells [I]. Controls [0] is LinkButton)
{
String sortOrder;
Int sortOrderNo;
String column = (LinkButton) dgItem. Cells [I]. Controls [0]). CommandArgument;
SearchSortExpression (sortColumns, column, out sortOrder, out sortOrderNo );
If (sortOrderNo> 0)
{
String sortImgLoc = (sortOrder. Equals ("ASC ")? SortAscImageUrl: SortDescImageUrl );

If (sortImgLoc! = String. Empty)
{
Image imgSortDirection = new Image ();
ImgSortDirection. ImageUrl = sortImgLoc;
DgItem. Cells [I]. Controls. Add (imgSortDirection );

}
Else
{

If (AllowMultiColumnSorting)
{
Literal litSortSeq = new Literal ();
LitSortSeq. Text = sortOrderNo. ToString ();
DgItem. Cells [I]. Controls. Add (litSortSeq );

}
}
}
}
}

}
}