Develop Reference

Making a DataGridViewColumn sortable

I work in C-sharp on ASP NET 4.
I need to add a sorting function to a column in a GridView. I've set the AllowSorting-property on the GridView to true and added sort expressions to the column.
Unfortunately, the sorting isn't working in the GridView.
Below is my code-behind-file for the column that should be able to sort, but I get the error
CS1502: The best overloaded method match for 'System.Data.DataView.DataView(System.Data.DataTable)' has some invalid arguments
on this line:
DataView sortedView = new DataView(BindData());
Code behind:
string sortingDirection;
public SortDirection dir
{
get
{
if (ViewState["dirState"] == null)
{
ViewState["dirState"] = SortDirection.Ascending;
}
return (SortDirection)ViewState["dirState"];
}
set
{
ViewState["dirState"] = value;
}
}
public string SortField
{
get
{
return (string)ViewState["SortField"] ?? "Name";
}
set
{
ViewState["SortField"] = value;
}
}
protected void gvProducts_Sorting(object sender, GridViewSortEventArgs e)
{
sortingDirection = string.Empty;
if (dir == SortDirection.Ascending)
{
dir = SortDirection.Descending;
sortingDirection = "Desc";
}
else
{
dir = SortDirection.Ascending;
sortingDirection = "Asc";
}
DataView sortedView = new DataView(RetrieveProducts());
sortedView.Sort = e.SortExpression + " " + sortingDirection;
SortField = e.SortExpression;
gvProducts.DataSource = sortedView;
gvProducts.DataBind();
}
protected void gvProducts_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
if (dir == SortDirection.Ascending)
{
sortingDirection = "Asc";
}
else
{
sortingDirection = "Desc";
}
DataView sortedView = new DataView(RetrieveProducts());
sortedView.Sort = SortField + " " + sortingDirection;
gvProducts.DataSource = sortedView;
gvProducts.PageIndex = e.NewPageIndex;
gvProducts.DataBind();
}
private void BindData()
{
gvProducts.DataSource = RetrieveProducts();
gvProducts.DataBind();
}
private DataSet RetrieveProducts()
{
DataSet dsProducts = new DataSet();
string sql = " ... ";
using (OdbcConnection cn =
new OdbcConnection(ConfigurationManager.ConnectionStrings["ConnMySQL"].ConnectionString))
{
cn.Open();
using (OdbcCommand cmd = new OdbcCommand(sql, cn))
{
........
}
}
return dsProducts;
}
Edit #1
DataView sortedView = new DataView(dsProducts.Tables[0]);
Edit # 2
I have added in aspx page:
<asp:BoundField DataField="Name" HeaderText="Name" SortExpression="Name" />
But If clicked in Column Name I have this new error:
System.IndexOutOfRangeException: Cannot find table 0.
on this line:
Line 100: DataView sortedView = new DataView(dsProducts.Tables[0]);

The DataView class has only three constructors, in which one is default constructor DataView(), second one takes a DataTable as an argument DataView(DataTable), the other one takes four arguments DataView(DataTable, String, String, DataViewRowState).
The DataView constructor expects arguments of any one of these types, but your code has argument of some other type. That's the error.
Your BindData method should return a DataTable object,
//This function should return a Datatable
private void BindData()
{
gvProducts.DataSource = RetrieveProducts();
gvProducts.DataBind();
}
which you can pass into your DataView here.
DataView sortedView = new DataView(BindData());
For your second edit,
System.IndexOutOfRangeException: Cannot find table 0.
on this line:
Line 100: DataView sortedView = new DataView(dsProducts.Tables[0]);
I guess the dataset is empty, the error clearly states that there isn't any table in the dataset at position 0. So check whether your dataset has tables or not. Might be your sql request didn't get any table to fill in the dataset.
Else you might have created a new instance of the dataset.

Dynamic sorting of Gridview

I am working of datagrid sorting. But GridViewStudents.dataSource is returning null in sorting function. I tried using session & viewstate. But doesn't work.
Any help appreciated.
My asp code for datagrid:
<asp:GridView ID="GridViewStudents" runat="server" AllowSorting="True"
onsorting="GridViewStudents_Sorting" ></asp:GridView>
Sorting function:
protected void GridViewStudents_Sorting(object sender, GridViewSortEventArgs e)
{
DataTable dataTable = GridViewStudents.DataSource as DataTable;
if (dataTable != null)
{
DataView dataView = new DataView(dataTable);
GridViewStudents.Sort = e.SortExpression + " " + ConvertSortDirectionToSql(e.SortDirection);
GridViewStudents.DataSource = dataView;
GridViewStudents.DataBind();
}
}
Sorting helper function:
private string ConvertSortDirectionToSql(SortDirection sortDirection)
{
string newSortDirection = String.Empty;
switch (sortDirection)
{
case SortDirection.Ascending:
newSortDirection = "ASC";
break;
case SortDirection.Descending:
newSortDirection = "DESC";
break;
}
return newSortDirection;
}

Apply automatic sorting mode
dataGridView1.Columns["ColName"].SortMode = DataGridViewColumnSortMode.Automatic;
Try this....
DataGridView control is sorted using a column with a SortMode property value of Automatic, a sorting glyph is automatically displayed in the column header.

Make sure that you rebind your Gridview on each roundtrip. The datasource of a gridview is not automatically stored in gridview or viewstate. If you need to access the datasource, you need to propagate the datasource first.

I found the solution.
Hope it is useful for others.
For anyone who come across DataGridView sorting problem.
Remember 4 steps.
Declare global dataset object
static DataSet ds = null;
Load data to grid
if (!IsPostBack)
{
loadData();
}
Write sorting function
protected void GridViewStudents_Sorting(object sender, GridViewSortEventArgs e)
{
DataTable dataTable = new DataTable();
dataTable = ds.Tables[0];
if (dataTable != null)
{
DataView dataView = new DataView(dataTable);
dataView.Sort = e.SortExpression + " " + ConvertSortDirectionToSql(e.SortDirection);
GridViewStudents.DataSource = dataView;
GridViewStudents.DataBind();
}
}
Sorting helper function
private string ConvertSortDirectionToSql(SortDirection sortDirection)
{
string newSortDirection = String.Empty;
switch (sortDirection)
{
case SortDirection.Ascending:
newSortDirection = "ASC";
break;
case SortDirection.Descending:
newSortDirection = "DESC";
break;
}
return newSortDirection;
}

Sorting gridview

I have a gridview where I bind a datasource, and I had to add sorting for this gridview; I added the code below to that, but it didn't work well.
private string ConvertSortDirectionToSql(SortDirection sortDireciton)
{
string m_SortDirection = String.Empty;
switch (sortDireciton)
{
case SortDirection.Ascending:
m_SortDirection = "ASC";
break;
case SortDirection.Descending:
m_SortDirection = "DESC";
break;
}
return m_SortDirection;
}
protected void GridView1_Sorting(object sender, GridViewSortEventArgs e)
{
DataTable m_DataTable = GridView1.DataSource as DataTable;
if (m_DataTable != null)
{
DataView m_DataView = new DataView(m_DataTable);
m_DataView.Sort = e.SortExpression + " " + ConvertSortDirectionToSql(e.SortDirection);
GridView1.DataSource = m_DataView;
GridView1.DataBind();
}
}

You can use this, as I had the same problem, and I solved it like this.
public string SortingExpression
{
get
{
if (this.ViewState["SortExpression"] == null)
return "";
else
return (string)this.ViewState["SortExpression"];
}
set
{
this.ViewState["SortExpression"] = value;
}
}
protected void GridView1_Sorting(object sender, GridViewSortEventArgs e)
{
DataTable m_DataTable = GridView1.DataSource as DataTable;
if (m_DataTable != null)
{
DataView m_DataView = new DataView(m_DataTable);
SortingExpression = e.SortExpression + " " + (SortingExpression.Contains("ASC") ? "DESC" : "ASC");
m_DataView.Sort =SortingExpression;
GridView1.DataSource = m_DataView;
GridView1.DataBind();
}
}

Maybe this could help if your sortdirection is always ascending.

Try this out. This method worked for me.
dt is the datatable containing the values.
protected void onSorting_Gridview1(object sender, GridViewSortEventArgs e)
{
string _sortDirection = dir.ToString();
if(_sortDirection.Equals("Ascending"))
{
_sortDirection = "ASC";
dir = SortDirection.Descending;
}
else
{
_sortDirection="DESC";
dir = SortDirection.Ascending;
}
if (dt != null)
{
//Sort the data.
dt.DefaultView.Sort = e.SortExpression + " " + _sortDirection;
gridView1.DataSource = dt;
gridView1.DataBind();
}
}
public SortDirection dir
{
get
{
if (ViewState["DIR"] == null)
{
ViewState["DIR"] = SortDirection.Ascending;
}
return (SortDirection)ViewState["DIR"];
}
set
{
ViewState["DIR"] = value;
}
}

Sorting in gridview is not working

I am trying Sorting functionality in Grid view but its not working.Can some body help?
Code:
private string ConvertSortDirectionToSql(SortDirection sortDirection)
{
string newSortDirection = String.Empty;
switch (sortDirection)
{
case SortDirection.Ascending:
newSortDirection = "ASC";
break;
case SortDirection.Descending:
newSortDirection = "DESC";
break;
}
return newSortDirection;
}
protected DataSet FillDataSet()
{
string source = "Database=GridTest;Server=Localhost;Trusted_Connection=yes";
con = new SqlConnection(source);
cmd = new SqlCommand("proc_mygrid", con);
ds = new DataSet();
da = new SqlDataAdapter(cmd);
da.Fill(ds);
GridView1.DataSource = ds;
GridView1.DataBind();
return ds;
}
protected void GridView1_Sorting(object sender, GridViewSortEventArgs e)
{
DataTable dt = GridView1.DataSource as DataTable;
if (dt != null)
{
DataView dv = new DataView(dt);
dv.Sort = e.SortExpression + " " + ConvertSortDirectionToSql(e.SortDirection);
GridView1.DataSource = dv;
GridView1.DataBind();
}
Here dt is coming null.why? pls help thanks.
EDIT:
enter code here <asp:GridView ID="GridView1" runat="server" CellPadding="4" ForeColor="#333333"
GridLines="None" AllowPaging="true" AllowSorting="true" PageSize="12"
onpageindexchanging="GridView1_PageIndexChanging"
onsorting="GridView1_Sorting">
EDIT(Total code)
public partial class _Default : System.Web.UI.Page
{
SqlConnection con;
SqlCommand cmd;
DataSet ds;
SqlDataAdapter da;
protected void Page_Load(object sender, EventArgs e)
{
}
private string ConvertSortDirectionToSql(SortDirection sortDirection)
{
string newSortDirection = String.Empty;
switch (sortDirection)
{
case SortDirection.Ascending:
newSortDirection = "ASC";
break;
case SortDirection.Descending:
newSortDirection = "DESC";
break;
}
return newSortDirection;
}
protected DataSet FillDataSet()
{
string source = "Database=GridTest;Server=Localhost;Trusted_Connection=yes";
con = new SqlConnection(source);
cmd = new SqlCommand("proc_mygrid", con);
ds = new DataSet();
da = new SqlDataAdapter(cmd);
da.Fill(ds);
GridView1.DataSource = ds;
GridView1.DataBind();
return ds;
}
protected void GetValues(object sender, EventArgs e)
{
FillDataSet();
}
protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
int newPagenumber = e.NewPageIndex;
GridView1.PageIndex = newPagenumber;
GridView1.DataSource = FillDataSet();
GridView1.DataBind();
}
protected void GridView1_Sorting(object sender, GridViewSortEventArgs e)
{
DataSet ds = FillDataSet();
DataTable dt = ds.Tables[0];
if (dt != null)
{
dt.DefaultView.Sort = e.SortExpression + " " + ConvertSortDirectionToSql(e.SortDirection);
GridView1.DataSource = dt;
GridView1.DataBind();
}

CODE:
private string GetSortDirection(string column)
{
string sortDirection = "DESC";
string sortExpression = ViewState["SortExpression"] as string;
if (sortExpression != null)
{
if (sortExpression == column)
{
string lastDirection = ViewState["SortDirection"] as string;
if ((lastDirection != null) && (lastDirection == "DESC"))
{
sortDirection = "ASC";
}
}
}
ViewState["SortDirection"] = sortDirection;
ViewState["SortExpression"] = column;
return sortDirection;
}
protected void GridView1_Sorting(object sender, GridViewSortEventArgs e)
{
DataTable dt = ((DataSet)Session["myDataSet"]).Tables[0];
dt.DefaultView.Sort = e.SortExpression + " " + GetSortDirection(e.SortExpression);
GridView1.DataSource = dt;
GridView1.DataBind();
}

Because you're setting a DataSet as DataSource and then casting it to DataTable with the operator as.
The 'as' operator in C# is a tentative cast - if it's impossible to cast (types are not compatible) instead of throwing an exception as the direct cast the 'as' operator sets the reference to null.
If you only have one datatable in your dataset then you can get the first element like this:
ds.Tables[0];
... or use the name of the table:
ds.Tables["myTable"];
in your case you can try...
DataTable dt = GridView1.DataSource.Tables[0] as DataTable;
Hope it helps!
EDIT:
with regards to your sorting problem (once you get the datatable):
if (dt != null)
{
dt.DefaultView.Sort = e.SortExpression + " " + ConvertSortDirectionToSql(e.SortDirection);
GridView1.DataBind();
}
You can do this because dt is a reference to the exact same object that's already set as DataSource for your grid. It should do the trick - if not there's smt else I am missing (such as we're sorting the wrong table meaning you have more than one table in the DataSet).
EDIT:
had a look at your code. I don't know exactly when GetValues gets fired but I suspect it's causing your problem (I think it might be overriding your sorting or smt along those lines).
If you comment out FillDataSource from getValues and modify your PageLoad to do this:
void Page_Load(Object sender, EventArgs e)
{
// Load data only once, when the page is first loaded.
if (!IsPostBack)
{
Session["myDataSet"] = FillDataSet();
}
}
then in your sort method you retrieve the DataSource like this:
DataTable dt = ((DataSet)Session["myDataSet"]).Tables[0];
Also you can retrieve the DataSet from session in your pagination handler method.
You should also notice an improvement in performance since you're retrieving the stuff form the db just once.
Give it a shot!

In Testing.aspx.cs
protected void GridView1_Sorting(object sender, GridViewSortEventArgs e)
{
if (dataset != null)
{
datatable = dataset.Tables[0];
DataView dataView = new DataView(datatable);
dataView.Sort = e.SortExpression;
GridView1.DataSource = dataView;
GridView1.DataBind();
}
}
In Testing.aspx
<asp:GridView ID="GridView1" runat="server"
AllowSorting="True" OnSorting="GridView1_Sorting">

Code to create Sorting for a GridView in ASP.net in Code Behind?

This is my code code for the Page_Load Event
OdbcConnection myConnection;
DataSet dataSet = new DataSet();
OdbcDataAdapter adapter;
//making my connection
myConnection = new OdbcConnection(ConfigurationManager.ConnectionStrings ["ODBC_ConnectionString"].ConnectionString);
adapter = new OdbcDataAdapter("SELECT * from Company", myConnection);
adapter.Fill(dataSet, "MyData");
GridView1.DataSource = dataSet;
Session["DataSource"] = dataSet;
GridView1.DataBind();
This is my code for the PageIndexChanging event and it all works fine.
DataSet ds = new DataSet();
if (Session["DataSource"] != null)
ds = ((DataSet)Session["DataSource"]);
GridView1.DataSource = ds;
GridView1.PageIndex = e.NewPageIndex;
this.GridView1.DataBind();
Now what code do i need to create the Sorting event?
protected void GridView1_Sorting(object sender, GridViewSortEventArgs e)
{
?????????????????????????
}
Etienne

I usually do this:
public string SortField {
get {
return (string) ViewState["_sortField"];
}
set {
ViewState["_sortField"] = value;
}
}
public string SortDir {
get {
return (string) ViewState["_sortDir"];
}
set {
ViewState["_sortDir"] = value;
}
}
Put your code to do databinding into another Method because you have to call it during Sort, Paging, and when your page first loads. Call it DoDataBind() for example. Then you have in DoDataBind()
DataTable dt = yourDataSet.Tables[0];
dt.DefaultView.Sort = SortField + " " + SortDir;
GridView1.DataSource = dt.DefaultView;
GridView1.DataBind();
Then your event looks like this:
protected void GridView1_Sorting(object sender, GridViewSortEventArgs e) {
if (e.SortExpression == SortField && SortDir != "desc") {
SortDir = "desc";
}
else {
SortDir = "asc";
}
SortField = e.SortExpression;
DoDataBind();
}
Then in your aspx page you'll need to specify what the SortExpression is. For example something like this:
<asp:BoundField DataField="FIRSTNAME"
HeaderText="First Name" SortExpression="FIRSTNAME" />

You can filter and sort your dataset using:
ds.Tables[0].Select(filterExp, sortExp, etc...);