asked on

paging on a datalist with custom object(Arraylist) as datasource

i'm reading directory contents and populating the names of the files in an objectCollection that inherits from the arraylistclass and using it as a datasource for a datalist. How can I enable paging for this datalist. There is a lot of examples using the dataadapter, but i'm not connecting to a db. please advice

davidlars99

I think for you to better understand paging without database would be to look at something that looks like a little shopping cart example, you can also use arrays for "Data Items" or you can even generate columns by "For.. Next" loop and put them into "DataSet" like so... :)

----------------
example.aspx
----------------

<%@ Import Namespace="System.Data" %>
<%@ Page Language="VB" Debug="True" %>
<HTML>
<HEAD>
<Script Language="vb" Runat="Server">

Dim ds As DataSet, _
      dt As DataTable, _
      dc As DataColumn, _
      dr As DataRow, _
      PKColumn(1) As DataColumn

Private Sub Page_Load(s As Object, e As EventArgs)
      ds=New DataSet()
      dt=New DataTable("Cart")

      dc=New DataColumn("Item ID", GetType(Integer))
      dc.AutoIncrement=True
      dc.AutoIncrementSeed=1
      dc.AutoIncrementStep=1
      dc.Unique=True
      dt.Columns.Add(dc)
      PKColumn(0)=dc
      dt.PrimaryKey=PKColumn

      dc=New DataColumn("Item Name", GetType(String))
      dt.Columns.Add(dc)

      dc=New DataColumn("Quantity", GetType(Integer))
      dt.Columns.Add(dc)

      dc=New DataColumn("Price", GetType(Decimal))
      dt.Columns.Add(dc)

      dr=dt.NewRow()
      dr("Item Name")="Data Item 1"
      dr("Quantity")=1
      dr("Price")=19.99
      dt.Rows.Add(dr)

      dr=dt.NewRow()
      dr("Item Name")="Data Item 2"
      dr("Quantity")=1
      dr("Price")=49.99
      dt.Rows.Add(dr)

      dr=dt.NewRow()
      dr("Item Name")="Data Item 3"
      dr("Quantity")=1
      dr("Price")=69.99
      dt.Rows.Add(dr)

      dr=dt.NewRow()
      dr("Item Name")="Data Item 4"
      dr("Quantity")=1
      dr("Price")=19.99
      dt.Rows.Add(dr)

      dr=dt.NewRow()
      dr("Item Name")="Data Item 5"
      dr("Quantity")=1
      dr("Price")=49.99
      dt.Rows.Add(dr)

      dr=dt.NewRow()
      dr("Item Name")="Data Item 6"
      dr("Quantity")=1
      dr("Price")=69.99
      dt.Rows.Add(dr)

      dr=dt.NewRow()
      dr("Item Name")="Data Item 7"
      dr("Quantity")=1
      dr("Price")=19.99
      dt.Rows.Add(dr)

      dr=dt.NewRow()
      dr("Item Name")="Data Item 8"
      dr("Quantity")=1
      dr("Price")=49.99
      dt.Rows.Add(dr)

      dr=dt.NewRow()
      dr("Item Name")="Data Item 0"
      dr("Quantity")=1
      dr("Price")=69.99
      dt.Rows.Add(dr)

      ds.Tables.Add(dt)

      cart.DataSource=ds.Tables("cart").DefaultView
      cart.DataBind()

      Dim total As Decimal
      total=dt.Compute("Sum(Price)", Nothing)
      lblmsg.Text="Order Total: " & total.ToString()
End Sub

Private Sub BindData()
      cart.DataSource=ds.Tables("cart").DefaultView
      cart.DataBind()
End Sub

Private Sub dg_Paging(o As Object, e As DataGridPageChangedEventArgs)
      cart.CurrentPageIndex=e.NewPageIndex
      BindData()
End Sub

</Script>
<TITLE></TITLE>
</HEAD>
<BODY>

<form runat="server">
      <asp:datagrid id="cart" runat="server" autogeneratecolumns="true"
            allowpaging="true"
            pagesize="2"
            pagerstyle-mode="numericpages"
            onpageindexchanged="dg_Paging"
      />
      <br>
      <asp:label id="lblmsg" runat="server" />
</form>

</BODY>
</HTML>

davidlars99

try to change above datagrid with this

<asp:datagrid id="cart" runat="server" autogeneratecolumns="true"
      allowpaging="true"
      pagesize="2"
      pagerstyle-nextpagetext="Next >"
      pagerstyle-prevpagetext="< Prev"
      onpageindexchanged="dg_Paging"
/>

this will present paging with "Next... Prev..." link buttons

vinny45

ASKER

good examples but i need one for a datalist

davidlars99

like this..?

<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.IO" %>
<%@ Page Language="C#" Debug="True" %>
<html>
<script language="C#" runat="server">

string [] arr;

void Page_Load( Object sender , EventArgs e){
      arr=Directory.GetDirectories("C:\\Windows");
      if(!IsPostBack){
            Session["i"]=0;
            BuildGrid();
      }
}

public void BuildGrid(){
      DataTable dt=new DataTable("Windows");
      DataColumn dc=new DataColumn("Item", Type.GetType("System.String"));
      dt.Columns.Add(dc);
      DataRow dr;
      int i;

      for (i=(int)Session["i"];i<((int)Session["i"]+(int.Parse(PageSize.Value)));i++){
            dr=dt.NewRow();
            dr["Item"]=arr[i];
            dt.Rows.Add(dr);
      }
MyDataList.DataSource = dt;
MyDataList.DataBind();

TotalSize.Value=(arr.Length-2).ToString();
lblmsg.Text="(Total Count: "+(arr.Length-2).ToString()+")";
}

public void Page_DataList(object sender, EventArgs e){
if(((LinkButton)sender).ID=="Prev"){
                  CurrentPage.Value=(int.Parse(CurrentPage.Value)-1).ToString();
                  Session["i"]=(int)Session["i"]-(int.Parse(PageSize.Value));

}
else if(((LinkButton)sender).ID=="Next"){
                  CurrentPage.Value=(int.Parse(CurrentPage.Value)+1).ToString();
                  Session["i"]=(int)Session["i"]+(int.Parse(PageSize.Value));
}
BuildGrid();
}

</script>
<body>
<h3>Directory Listing <asp:label id="lblmsg" runat="server" /></h3>
<form runat="server">
      <asp:DataList id="MyDataList" RepeatColumns="1" RepeatDirection="Horizontal" runat="server">
            <ItemTemplate>
                  <%# DataBinder.Eval(Container.DataItem, "Item") %>
            </ItemTemplate>
</asp:DataList>

      <input type="hidden" id="PageSize" value="10" runat="server">
      <input type="hidden" id="CurrentPage" value="1" runat="server">
      <input type="hidden" id="TotalSize" runat="server">
      <br>
      <asp:LinkButton id="Prev" Text="<< Previous" OnClick="Page_DataList" runat="server" />
       
      <asp:LinkButton id="Next" Text="Next >>" OnClick="Page_DataList" runat="server" />
</form>
</body>
</html>

davidlars99

just makes sure you use correct directory path here

arr=Directory.GetDirectories("C:\\Windows");

davidlars99

I didn't pay attention at "Page_Datalist" sub you have to change it to this:

public void Page_DataList(object sender, EventArgs e){
if(((LinkButton)sender).ID=="Prev"){
                  CurrentPage.Value=(int.Parse(CurrentPage.Value)-1).ToString();
                  if(((int)Session["i"]-(int.Parse(PageSize.Value)))<=0)
                        Session["i"]=0;
                  else
                        Session["i"]=(int)Session["i"]-(int.Parse(PageSize.Value));
}
else if(((LinkButton)sender).ID=="Next"){
                  CurrentPage.Value=(int.Parse(CurrentPage.Value)+1).ToString();
                  if(((int)Session["i"]+(int.Parse(PageSize.Value)))>=int.Parse(PageSize.Value))
                        Session["i"]=arr.Length-int.Parse(PageSize.Value);
                  else
                        Session["i"]=(int)Session["i"]+(int.Parse(PageSize.Value));
}
BuildGrid();
}

vinny45

ASKER

this is what i ended up doing other solutions are very similar and might be better than mine. there is a PagedDataSource (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemwebuiwebcontrolspageddatasourceclasstopic.asp) object that u fill with a datasource and you can set its propeties and bind it to a datalist: well heres the code

private void bind()
            {
              //my custom object
PhotoGallery gallery = new PhotoGallery();

//instantiate the pagedatasource obj
                  PagedDataSource objPds = new PagedDataSource();

//set the PhotoGallery parameters to retrieve the info
                  gallery.Level = this.level;
                  gallery.PicturePath = this.picturePath;
                  gallery.Folder = this.folder;

//get the directory listing
                  objPds.DataSource = gallery.Fill(); //returns collection that inherits from the arraylist

//set the pagedatasource properites
                  objPds.AllowPaging = true;
                  objPds.PageSize = 9;
                  objPds.CurrentPageIndex = CurrentPage;

                  lblCurrentPage.Text = "Page: " + (CurrentPage + 1).ToString() + " of "
                        + objPds.PageCount.ToString();

                  // Disable Prev or Next buttons if necessary
                  cmdPrev.Enabled = !objPds.IsFirstPage;
                  cmdNext.Enabled = !objPds.IsLastPage;

                  //bind the pagedatasource to the datalist
                  PortfolioDatalist.DataSource = objPds;
                  PortfolioDatalist.DataBind();

            }

            private void cmdPrev_Click(object sender, System.EventArgs e)
            {
                  // Set viewstate variable to the previous page
                  CurrentPage -= 1;

                  // Reload control
                  bind();
            }

            private void cmdNext_Click(object sender, System.EventArgs e)
            {
                  // Set viewstate variable to the next page
                  CurrentPage += 1;

                  // Reload control
                  bind();
            }

public int CurrentPage
            {
                  get
                  {
                        // look for current page in ViewState
                        object o = this.ViewState["_CurrentPage"];
                        if (o == null)
                              return 0; // default to showing the first page
                        else
                              return (int) o;
                  }

                  set
                  {
                        this.ViewState["_CurrentPage"] = value;
                  }
            }

ASKER CERTIFIED SOLUTION

davidlars99

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial