Agha Usman

Lives in Karachi (Pakistan) and work for Ciber Strategies

May 2009 - Posts

How to show and select month/year in Calendar Extender

In this post I will explain you, How to make calendar extender control to show month / year view by default and instead of selecting dates how can we use calendar extender to select months.

Before I start, let me say that I got extensive support from this forum post http://forums.asp.net/t/1349086.aspx. Thanks to Zhi-Qiang Ni, but the way he follow was a little bit lengthy. However, all credit still goes to him because I gain the exact idea from his post.

Let me start by creating a calendar extender control and attach it to a textbox. 

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<cc1:CalendarExtender ID="TextBox1_CalendarExtender" runat="server" OnClientHidden="onCalendarHidden"  OnClientShown="onCalendarShown" BehaviorID="calendar1"
    Enabled="True" TargetControlID="TextBox1">
</cc1:CalendarExtender>


Now, in extender markup, notice onClientHidden and OnClientShown event which I implemented as below. 

function onCalendarShown() {
 
     var cal = $find("calendar1");
     //Setting the default mode to month
     cal._switchMode("months", true);
     
     //Iterate every month Item and attach click event to it
     if (cal._monthsBody) {
         for (var i = 0; i < cal._monthsBody.rows.length; i++) {
             var row = cal._monthsBody.rows[i];
             for (var j = 0; j < row.cells.length; j++) {
                 Sys.UI.DomEvent.addHandler(row.cells[j].firstChild, "click", call);
             }
         }
     }
 }
 
 function onCalendarHidden() 
 {
     var cal = $find("calendar1");
     //Iterate every month Item and remove click event from it
       if (cal._monthsBody) {
         for (var i = 0; i < cal._monthsBody.rows.length; i++) {
             var row = cal._monthsBody.rows[i];
             for (var j = 0; j < row.cells.length; j++) {
                 Sys.UI.DomEvent.removeHandler(row.cells[j].firstChild,"click",call);
             }
         }
     }
 
 }

Pretty simple, In onCalendarShown method I just set the default mode to month and then iterate the control to get month item and attach on click event to it. So that, it will not go further to show us dates of that month and select the first day of that month instead.

Where as, In onCalendarHidden I am simply detaching the click event from month items. Now notice the last parameter of Sys.UI.DomEvent.addHandler function, it is the name of the function which will do the rest of the magic as below. 

function call(eventElement)
        {
            var target = eventElement.target;
            switch (target.mode) {
            case "month":
                var cal = $find("calendar1");
                cal._visibleDate = target.date;
                cal.set_selectedDate(target.date);
                cal._switchMonth(target.date);
                cal._blur.post(true);
                cal.raiseDateSelectionChanged();
                break;
            }
        }

Here we are simply selecting the month as the selected date of calendar control. and finally the control will look like as below.

cal_extender

You can get the source code from here :
http://cid-cdbfe38dc780f729.skydrive.live.com/self.aspx/.Public/Calendar%20Extender%20Month.zip

Posted: May 31 2009, 04:16 AM by aghausman12 | with 4 comment(s)
Filed under: , ,
Show images on Grid View from File Stream SQL Server 2008

 

Background :

In my last post about SQL Server 2008 new feature File Stream (Saving and Retrieving File Using FileStream SQL Server 2008), we did an example of saving an image to the file stream and then retrieve it back and make it available for download.

The result of that example looks like as below.

fs_snapshot1

But, one has to press the button to download the image file. One of my blog reader raise a point that he wants to display the same image instead of Get File button which is going to download.

Introduction :

So, in this post I will explain you, how can we rendered the image before actually downloading it and show that in the grid (Maybe as thumbnail, but this post will not discuss any thing about generating thumbnails).

Note : If you want to know. How to add files to the file stream please see my post Saving and Retrieving File Using FileStream SQL Server 2008

Getting Started:

We will complete this goal by using HttpHandler. lets first alter our gridview. 

   1: <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" 
   2:         onrowcommand="GridView1_RowCommand">
   3:         <Columns>
   4:             <asp:BoundField DataField="ID" HeaderText="ID" />
   5:             <asp:BoundField DataField="SystemNumber" HeaderText="System Id" />
   6:             <asp:TemplateField>
   7:                 <ItemTemplate>
   8:                     <asp:LinkButton ID="lbGetFile" runat="server" CommandName="GetFile" CommandArgument='<%#Eval("ID") %>' ><img src='<%#Eval("ID") %>.jpg' /></asp:LinkButton>
   9:                 </ItemTemplate>
  10:             </asp:TemplateField>
  11:         </Columns>
  12:     
  13:     </asp:GridView>

 


Notice the link button on line no 8. I have now specify an image tag inside Link button and pass the primarykey of tbl_files as the file name along with random “.jpg”. So that, it can finally looks like as follows

8e7af927-cc7e-4515-8409-d94566246de8.jpg
a3de6abb-382f-484c-822c-7f93e0ede0c7.jpg
4ad64bf1-ea6e-4228-bdc0-300a0cd90f5a.jpg

The idea is, I will attach the handler with jpg file type to accommodate the incoming requests.

Now, lets create HttpHandler and name it “imageHandler” 

public class imageHandler : IHttpHandler
{
 
    #region IHttpHandler Members
 
    public bool IsReusable
    {
        get { return false; }
    }
 
    public void ProcessRequest(HttpContext context)
    {
        //Getting file name from incoming request.
        string url = Path.GetFileName(context.Request.Path);
        Guid FileId;
     
        try
        {
            //Since we have all our primary keys stored in GUID
            //Try parsing the file name to Guid
            FileId = new Guid(Path.GetFileNameWithoutExtension(url));
 
        }
        catch (FormatException)
        {
            //If some other JPG file is requested
            FileId = Guid.Empty;
        }
 
        if (FileId != Guid.Empty) // If the call is for valid Image File Stream
        {
            SqlConnection objSqlCon = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
            objSqlCon.Open();
            SqlTransaction objSqlTran = objSqlCon.BeginTransaction();
 
            SqlCommand objSqlCmd = new SqlCommand("FileGet", objSqlCon, objSqlTran);
            objSqlCmd.CommandType = CommandType.StoredProcedure;
 
            SqlParameter objSqlParam1 = new SqlParameter("@ID", SqlDbType.VarChar);
            objSqlParam1.Value = FileId.ToString();
 
            objSqlCmd.Parameters.Add(objSqlParam1);
            string path = string.Empty;
            string fileType = string.Empty;
 
            using (SqlDataReader sdr = objSqlCmd.ExecuteReader())
            {
                while (sdr.Read())
                {
                    path = sdr[0].ToString();
                    fileType = sdr[1].ToString();
                }
 
            }
 
            objSqlCmd = new SqlCommand("SELECT GET_FILESTREAM_TRANSACTION_CONTEXT()", objSqlCon, objSqlTran);
 
            byte[] objContext = (byte[])objSqlCmd.ExecuteScalar();
 
 
            SqlFileStream objSqlFileStream = new SqlFileStream(path, objContext, FileAccess.Read);
 
            byte[] buffer = new byte[(int)objSqlFileStream.Length];
            objSqlFileStream.Read(buffer, 0, buffer.Length);
            objSqlFileStream.Close();
 
            objSqlTran.Commit();
 
            context.Response.AddHeader("Content-disposition", "attachment; filename=" + Path.GetFileName(path) + fileType);
            // Here you need to manage the download file stuff according to your need
            context.Response.ContentType = "application/octet-stream";
 
            context.Response.BinaryWrite(buffer);
        }
        else
        { // If the call is for some other JPG file, nothing to do with file stream.
            context.Response.WriteFile(context.Request.Path);
        }
    }

 

Well, read the comments I wrote in the code. That will of course help you to understand what actually I have done.

And then register the HttpHandler.

<httpHandlers>
    <add verb="*" path="*.jpg" type="LearningApp.imageHandler, LearningApp"/>
</httpHandlers>
Conclusion:

There we go, In this way we can show the images stored on file stream in grid view. You can download both VS 2008 and VS 2010 project files.

Posted: May 26 2009, 03:15 AM by aghausman12 | with 2 comment(s)
Filed under: , ,
Custom Paging in Grid view

So, it takes too long for me to write this post. even though I completed the coding stuff a week back but it is really hard to manage time these days.

In this post, I will explain and demonstrate you how to create custom paging in Grid view control. Paging which works like the Google Paging. Let me elaborate more, say for example you have a record set of 500 items and you want to display 10 items per page. Now what happen to the pages numbers. Either you use the default with “..” sign after 10th page link which cause the post back and then get some new page numbers. Or you want to make it like Google. i.e as soon as user move forward on page index, hide the previous pages and show the new numbers and when user is getting back hide new numbers and show the previous page links. following image can give you some idea what we are going to do.

gvpaging_sc


 gvpaging_sc2

To start, lets first create a Grid view . 

   1: <asp:GridView ID="GridView1" runat="server" AllowPaging="True" 
   2:     onrowcreated="GridView1_RowCreated" >
   3: </asp:GridView>

Yes, we have allow the paging but we are not going to use the default paging of asp.net. That is why we have write onrowcreated implementation in which we will simply detect and hide the pager row. 

   1: protected void GridView1_RowCreated(object sender, GridViewRowEventArgs e)
   2:  {
   3:      if (e.Row.RowType == DataControlRowType.Pager)
   4:      {
   5:          e.Row.Visible = false;
   6:      }
   7:  }

Now lets move to some global variables which we need through out our code. 

   1: const int pageSize = 10;
   2: const int pageDispCount = 10;
   3: private DataTable dt = new DataTable();

pagesSize : number of records we want to display per page.
pageDispCount : number of page numbers we want to display on custom paging.
dt : A datatable which we will use to store data and use it on different post backs.

Ok, now we need to get data from database, dump it to datatable and define the datasource of grid view. 

   1: protected void bindData()
   2: {
   3:     SqlConnection objSqlCon = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["AdventureWorksConnectionString"].ToString());
   4:     objSqlCon.Open();
   5:  
   6:     SqlDataAdapter objSqlDa = new SqlDataAdapter("select * from Production.Product", objSqlCon);
   7:     
   8:     objSqlDa.Fill(dt);
   9:  
  10:     GridView1.DataSource = dt;
  11:     GridView1.DataBind();
  12:  
  13:     managePaging(dt);
  14: }

 

 

On line number 13, managePaging function will be used later to implement the paging logic. But before that, lets understand that we have taken the datatable as a global variable and each time after postback when we try to read our datatable we will get no results because there is no state management for this object.

So lets override the LoadViewState and SaveViewState function of System.Web.UI.Page to save and restore the datatable by using viewstate.

 

   1: protected override object SaveViewState()
   2: {
   3:   object baseState = base.SaveViewState();
   4:   return new object[] { baseState, dt };
   5: }  
   6: protected override void LoadViewState(object savedState)
   7: {
   8:   object[] myState = (object[])savedState;
   9:   if (myState[0] != null)
  10:       base.LoadViewState(myState[0]);
  11:  
  12:   if (myState[1] != null)
  13:   {
  14:       dt = (DataTable) myState[1];
  15:       GridView1.DataSource = dt;
  16:       GridView1.DataBind();
  17:  
  18:       managePaging(dt);
  19:   }
  20:   
  21:   }

Well, SaveViewState function is simply putting the base.SaveViewState object and datatable in and object and returning it. A Simple Logic :)

Where as, LoadViewState is retrieving and type casting the object exactly in the sequence it was save in the SaveViewState method.

   1: protected void managePaging(DataTable _dt)
   2: {
   3:     if (_dt.Rows.Count > 0)
   4:     {
   5:  
   6:         // Variable declaration
   7:         int numberOfPages;
   8:         int numberOfRecords = dt.Rows.Count;
   9:         int currentPage = (GridView1.PageIndex);
  10:         StringBuilder strSummary = new StringBuilder();
  11:  
  12:  
  13:         // If number of records is more then the page size (specified in global variable)
  14:         // Just to check either gridview have enough records to implement paging
  15:         if (numberOfRecords > pageSize)
  16:         {
  17:             // Calculating the total number of pages
  18:             numberOfPages = (int)Math.Ceiling((double)numberOfRecords / (double)pageSize);
  19:         }
  20:         else
  21:         {
  22:             numberOfPages = 1;
  23:         }
  24:  
  25:  
  26:         // Creating a small summary for records.
  27:         strSummary.Append("Displaying <b>");
  28:  
  29:         // Creating X f X Records
  30:         int floor = (currentPage * pageSize) + 1;
  31:         strSummary.Append(floor.ToString());
  32:         strSummary.Append("</b>-<b>");
  33:         int ceil = ((currentPage * pageSize) + pageSize);
  34:  
  35:         //let say you have 26 records and you specified 10 page size, 
  36:         // On the third page it will return 30 instead of 25 as that is based on pageSize
  37:         // So this check will see if the ceil value is increasing the number of records. Consider numberOfRecords
  38:         if (ceil > numberOfRecords)
  39:         {
  40:             strSummary.Append(numberOfRecords.ToString());
  41:         }
  42:         else
  43:         {
  44:             strSummary.Append(ceil.ToString());
  45:         }
  46:  
  47:         // Displaying Total number of records Creating X of X of About X records.
  48:         strSummary.Append("</b> of About <b>");
  49:         strSummary.Append(numberOfRecords.ToString());
  50:         strSummary.Append("</b>Records</br>");
  51:  
  52:         
  53:         litPagingSummary.Text =  strSummary.ToString();
  54:  
  55:  
  56:         //Variable declaration 
  57:         //these variables will used to calculate page number display
  58:         int pageShowLimitStart = 1;
  59:         int pageShowLimitEnd = 1;
  60:  
  61:  
  62:  
  63:         // Just to check, either there is enough pages to implement page number display logic.
  64:         if (pageDispCount > numberOfPages)
  65:         {
  66:             pageShowLimitEnd = numberOfPages; // Setting the end limit to the number of pages. Means show all page numbers
  67:         }
  68:         else
  69:         {
  70:             if (currentPage > 4) // If page index is more then 4 then need to less the page numbers from start and show more on end.
  71:             {
  72:                 //Calculating end limit to show more page numbers
  73:                 pageShowLimitEnd = currentPage + (int)(Math.Floor((decimal)pageDispCount / 2));
  74:                 //Calculating Start limit to hide previous page numbers
  75:                 pageShowLimitStart = currentPage - (int)(Math.Floor((decimal)pageDispCount / 2));
  76:             }
  77:             else
  78:             {
  79:                 //Simply Displaying the 10 pages. no need to remove / add page numbers
  80:                 pageShowLimitEnd = pageDispCount;
  81:             }
  82:         }
  83:  
  84:         // Since the pageDispCount can be changed and limit calculation can cause < 0 values 
  85:         // Simply, set the limit start value to 1 if it is less
  86:         if (pageShowLimitStart < 1)
  87:             pageShowLimitStart = 1;
  88:  
  89:  
  90:         //Dynamic creation of link buttons
  91:  
  92:         // First Link button to display with paging
  93:         LinkButton objLbFirst = new LinkButton();
  94:         objLbFirst.Click += new EventHandler(objLb_Click);
  95:         objLbFirst.Text = "First";
  96:         objLbFirst.ID = "lb_FirstPage";
  97:         objLbFirst.CommandName = "pgChange";
  98:         objLbFirst.EnableViewState = true;
  99:         objLbFirst.CommandArgument = "1";
 100:  
 101:         //Previous Link button to display with paging
 102:         LinkButton objLbPrevious = new LinkButton();
 103:         objLbPrevious.Click += new EventHandler(objLb_Click);
 104:         objLbPrevious.Text = "Previous";
 105:         objLbPrevious.ID = "lb_PreviousPage";
 106:         objLbPrevious.CommandName = "pgChange";
 107:         objLbPrevious.EnableViewState = true;
 108:         objLbPrevious.CommandArgument = currentPage.ToString();
 109:  
 110:  
 111:         //of course if the page is the 1st page, then there is no need of First or Previous
 112:         if (currentPage == 0)
 113:         {
 114:             objLbFirst.Enabled = false;
 115:             objLbPrevious.Enabled = false;
 116:         }
 117:         else
 118:         {
 119:             objLbFirst.Enabled = true;
 120:             objLbPrevious.Enabled = true;
 121:         }
 122:  
 123:  
 124:         //Adding control in a place holder
 125:         plcPaging.Controls.Add(objLbFirst);
 126:         plcPaging.Controls.Add(new LiteralControl("&nbsp; | &nbsp;")); // Just to give some space 
 127:         plcPaging.Controls.Add(objLbPrevious);
 128:         plcPaging.Controls.Add(new LiteralControl("&nbsp; | &nbsp;"));
 129:  
 130:  
 131:         // Creatig page numbers based on the start and end limit variables.
 132:         for (int i = pageShowLimitStart; i <= pageShowLimitEnd; i++)
 133:         {
 134:             if ((Page.FindControl("lb_" + i.ToString()) == null) && i <= numberOfPages)
 135:             {
 136:                 LinkButton objLb = new LinkButton();
 137:                 objLb.Click += new EventHandler(objLb_Click);
 138:                 objLb.Text = i.ToString();
 139:                 objLb.ID = "lb_" + i.ToString();
 140:                 objLb.CommandName = "pgChange";
 141:                 objLb.EnableViewState = true;
 142:                 objLb.CommandArgument = i.ToString();
 143:  
 144:                 if ((currentPage + 1) == i)
 145:                 {
 146:                     objLb.Enabled = false;
 147:                 }
 148:  
 149:  
 150:                 plcPaging.Controls.Add(objLb);
 151:                 plcPaging.Controls.Add(new LiteralControl("&nbsp; | &nbsp;"));
 152:             }
 153:         }
 154:  
 155:         // Last Link button to display with paging
 156:         LinkButton objLbLast = new LinkButton();
 157:         objLbLast.Click += new EventHandler(objLb_Click);
 158:         objLbLast.Text = "Last";
 159:         objLbLast.ID = "lb_LastPage";
 160:         objLbLast.CommandName = "pgChange";
 161:         objLbLast.EnableViewState = true;
 162:         objLbLast.CommandArgument = numberOfPages.ToString();
 163:  
 164:         // Next Link button to display with paging
 165:         LinkButton objLbNext = new LinkButton();
 166:         objLbNext.Click += new EventHandler(objLb_Click);
 167:         objLbNext.Text = "Next";
 168:         objLbNext.ID = "lb_NextPage";
 169:         objLbNext.CommandName = "pgChange";
 170:         objLbNext.EnableViewState = true;
 171:         objLbNext.CommandArgument = (currentPage + 2).ToString();
 172:  
 173:         //of course if the page is the last page, then there is no need of last or next
 174:         if ((currentPage + 1) == numberOfPages)
 175:         {
 176:             objLbLast.Enabled = false;
 177:             objLbNext.Enabled = false;
 178:         }
 179:         else
 180:         {
 181:             objLbLast.Enabled = true;
 182:             objLbNext.Enabled = true;
 183:         }
 184:  
 185:  
 186:         // Adding Control to the place holder
 187:         plcPaging.Controls.Add(objLbNext);
 188:         plcPaging.Controls.Add(new LiteralControl("&nbsp; | &nbsp;"));
 189:         plcPaging.Controls.Add(objLbLast);
 190:         plcPaging.Controls.Add(new LiteralControl("&nbsp; | &nbsp;"));
 191:     }
 192:  
 193: }

Yes, the code is complex that is why I wrote proper comments which will let you understand the stuff easily.

One last thing which is left, is the implementation of dynamically created link button onclick event. 

   1: void objLb_Click(object sender, EventArgs e)
   2: {
   3:     plcPaging.Controls.Clear();
   4:     LinkButton objlb = (LinkButton)sender;
   5:     GridView1.PageIndex = (int.Parse(objlb.CommandArgument.ToString()) - 1);
   6:     
   7:     managePaging(dt);
   8: }

 

There it is, we have now completed Custom Paging in Grid View. If you want to download the source code, here is the VS 2008 Solution.

Modification:

I have been receiving emails regarding the issues of this post. Especially with the initial five page numbers. I have modified this post to fix the bug it had. Please feel free to point further issues. Also, the download links are also modified.

Posted: May 19 2009, 02:17 AM by aghausman12 | with 6 comment(s)
Filed under: , , ,
Datatable to JSON

In this post I will explain you, how can we serialize Datatable to JSON. So that, it can easily pass to JavaScript to get the AJAX done.

First of all fill a Datatable with some results. 

DataTable dt = new DataTable();
 
SqlConnection objSqlCon = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["AdventureWorksConnectionString"].ToString());
objSqlCon.Open();
 
SqlDataAdapter objSqlDa = new SqlDataAdapter("select * from Production.Product", objSqlCon);
 
objSqlDa.Fill(dt);

Now create a String Builder object that will contain the JSON text and JavascriptSerializer which will serialize the output in JSON.

StringBuilder objSb = new StringBuilder();
JavaScriptSerializer objSer = new JavaScriptSerializer();

Now here we are going to iterate each row and column of data table and put all of them in Dictionary

Dictionary<string, object> resultMain = new Dictionary<string, object>();
int index = 0;
 
foreach (DataRow dr in dt.Rows)
{
    Dictionary<string, object> result = new Dictionary<string, object>();
 
    foreach (DataColumn dc in dt.Columns)
    {
        result.Add(dc.ColumnName, dr[dc].ToString());
    }
    resultMain.Add(index.ToString(), result);
    index++;
}

Notice that, I have created a new dictionary object for every row and finally put all of the dictionaries in Another dictionary I.E. resultMain.

In the end, I have simply Serialize the resultMain Dictionary to render JSON.

A complete post of utilizing Datatable  in JavaScript through AJAX is in the process, I will post that soon.

Posted: May 16 2009, 05:53 PM by aghausman12 | with 3 comment(s)
Filed under: , , , ,
Authenticated File Access using HTTP Handler.

In this post I will explain you how authenticate the request directly coming to access a file that is downloadable. some thing like *.pdf or *.zip.

Mostly, people make it working by creating an *.aspx page and then write binary of that file in Response.WriteFile. So, user will have no idea where the file is coming from. now this is the fair approach but what if somebody, somehow know the path of downloadable files.

So, to stop the un authenticated access to our files, we will first create a session enable HTTP handler. 

public class MyHttpHandler : IHttpHandler, IReadOnlySessionState
{
 
    public void ProcessRequest(HttpContext context)
    {
        if (context.Session["userId"] == null)
        // I am using a session variable you can also use context.User.Identity.IsAuthenticated
        {
            context.Response.Redirect("/login.aspx?retUrl=" + context.Request.RawUrl);
            //Redirecting to the login page ... alternatively you can also set context.Response.StatusCode 
        }
    }
 
    public bool IsReusable
    {
 
        get { return false; }
    }
}

Now, once we have created that. Let me register my newly creater handler for *.zip and *.pdf files in web.config.

 

<httpHandlers>
  <add verb="*" path="*.zip" type="LearningApp.MyHttpHandler, LearningApp"/>
  <add verb="*" path="*.pdf" type="LearningApp.MyHttpHandler, LearningApp"/>
</httpHandlers>

That’s it. If you want more file types to be authenticated add more verbs in handler section of HttpHandler.

Don’t try to put *.* : That can create some serious problem because then each of your *.aspx, *asmx and all your logic stuff will need authentication.

Posted: May 08 2009, 03:21 AM by aghausman12 | with 4 comment(s)
Filed under: , ,
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