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Custom Paging in Grid view

19. May 2009 AngryCoder .net , asp.net , c# Comments (0)
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_scgvpaging_sc2To 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.Modifications: 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.

Datatable to JSON

16. May 2009 AngryCoder .net , asp.net , Javascript , c# , AJAX Comments (0)

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.

Authenticated File Access using HTTP Handler.

8. May 2009 AngryCoder .net , asp.net , c# Comments (0)

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.

Disable Special Keys in Win App C#

26. April 2009 AngryCoder .net , c# Comments (0)

Today, when I was planning to write an article on Grid View. I got a message from a very good friend of mine who is asking to disable the special keys(Windows Keys) in his application. When I start researching on it, I was thinking that it can be done using e.KeyChar but unfortunately, it is not showing any information about windows keys.

So in this post I will explain you, how can we disable the special keys (in our case windows keys) in C# Application.

1. Crete a c# windows application project
2. On the code behind of your default form add the following references

   1: using System.Diagnostics;
   2: using System.Runtime.InteropServices;

3. Now before the constructor of your form place the following code. 

   1: // Structure contain information about low-level keyboard input event
   2: [StructLayout(LayoutKind.Sequential)]
   3: private struct KBDLLHOOKSTRUCT
   4: {
   5:     public Keys key;
   6:     public int scanCode;
   7:     public int flags;
   8:     public int time;
   9:     public IntPtr extra;
  10: }
  11:  
  12: //System level functions to be used for hook and unhook keyboard input
  13: private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);
  14: [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
  15: private static extern IntPtr SetWindowsHookEx(int id, LowLevelKeyboardProc callback, IntPtr hMod, uint dwThreadId);
  16: [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
  17: private static extern bool UnhookWindowsHookEx(IntPtr hook);
  18: [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
  19: private static extern IntPtr CallNextHookEx(IntPtr hook, int nCode, IntPtr wp, IntPtr lp);
  20: [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
  21: private static extern IntPtr GetModuleHandle(string name);
  22: [DllImport("user32.dll", CharSet = CharSet.Auto)]
  23: private static extern short GetAsyncKeyState(Keys key);
  24:  
  25:  
  26: //Declaring Global objects
  27: private IntPtr ptrHook;
  28: private LowLevelKeyboardProc objKeyboardProcess;

4. Now add the following code on your constructor.

   1: public Form1()
   2: {
   3:     ProcessModule objCurrentModule = Process.GetCurrentProcess().MainModule; //Get Current Module
   4:     objKeyboardProcess = new LowLevelKeyboardProc(captureKey); //Assign callback function each time keyboard process
   5:     ptrHook = SetWindowsHookEx(13, objKeyboardProcess, GetModuleHandle(objCurrentModule.ModuleName), 0); //Setting Hook of Keyboard Process for current module
   6:  
   7:  
   8:     InitializeComponent();
   9: }

5. Now Implement the callback function 

   1: private IntPtr captureKey(int nCode, IntPtr wp, IntPtr lp)
   2: {
   3:     if (nCode >= 0)
   4:     {
   5:         KBDLLHOOKSTRUCT objKeyInfo = (KBDLLHOOKSTRUCT)Marshal.PtrToStructure(lp, typeof(KBDLLHOOKSTRUCT));
   6:  
   7:         if (objKeyInfo.key == Keys.RWin || objKeyInfo.key == Keys.LWin) // Disabling Windows keys
   8:         {
   9:             return (IntPtr)1;
  10:         }
  11:     }
  12:     return CallNextHookEx(ptrHook, nCode, wp, lp);
  13: }

6. Now go to your designer class and replace your dispose method.

   1: /// <summary>
   2: /// Clean up any resources being used.
   3: /// </summary>
   4: /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
   5: protected override void Dispose(bool disposing)
   6: {
   7:     if (disposing && (components != null))
   8:     {
   9:  
  10:         components.Dispose();
  11:     }
  12:     if (ptrHook != IntPtr.Zero)
  13:     {
  14:         UnhookWindowsHookEx(ptrHook);
  15:         ptrHook = IntPtr.Zero;
  16:     }
  17:     base.Dispose(disposing);
  18: }

So, in this way we can stop the windows key operation till your application is running.You can find the VS 2008 Source code here.

Pray your Prayers

23. April 2009 AngryCoder Islamic Stuff Comments (0)
Let us ask a question to ourselves, What will happen to us ? are we really prepared ...........

How to pass parameters to the dynamically added user control

15. April 2009 AngryCoder .net , asp.net , vb.net Comments (0)

In this post, I will explain how you can pass parameter to the dynamically added (from code behind) User Control. Most of you might aware of how we can achieve this in web application project. Following is the code for that 

   1: Dim objCon As Control = Page.LoadControl("~/Controls/MyControl.ascx")
   2: Ctype(objCon,MyControl).PropertyOne = "Test"
   3: Ctype(objCon,MyControl).PropertyTwo = "USAM"
   4: MyPanel.Controls.add(objCon)

Now what if you have a web site project which does not have the pre-compiled assemblies and you are no more able to access the class of your user control. That is what the sum of last two ays.

Here is how you can do that by using System.reflection. 

   1: Dim objCon As Control = Page.LoadControl("~/Controls/MyControl.ascx")
   2: 'Creating Dynamic Assmebly which holds control
   3: Dim objAssembly As Assembly = Compilation.BuildManager.GetCompiledAssembly("~/Controls/MyControl.ascx")
   4: 'You should definately know the name of your user control class
   5: Dim objType As Type = objAssembly.GetType("Controls_MyControl")
   6:  
   7: 'Properties
   8: Dim objPropOne As PropertyInfo = objType.GetProperty("PropertyOne")
   9: Dim objPropTwo As PropertyInfo = objType.GetProperty("PropertyTwo")
  10:  
  11: 'Setting Value of Properties
  12: bjPropOne.SetValue(objCon, 1, Nothing)
  13: objPropTwo.SetValue(objCon, 13, Nothing)
  14:  
  15: 'Finally placing control on the page
  16: pnlCommentsCon.Controls.Add(objCon)

So in this way you can pass parameters to the dynamically added user control.  

Get Repeater Control Output in String

13. April 2009 AngryCoder asp.net , vb.net Comments (0)

In this post I will share with you a small code snippet which will help you to get the repeater control output in string variable. 

   1: Dim sb As New StringBuilder()
   2: Dim objHtml As New HtmlTextWriter(New System.IO.StringWriter(sb))
   3:  
   4: If dt.Rows.Count > 0 Then
   5:     Repeater1.DataSource = dt
   6:     Repeater1.DataBind()
   7: End If
   8:  
   9: Repeater1.RenderControl(objHtml)
  10: Return sb.ToString()

 

Well, I have used a little trick here. The RenderControl method of repeater control can put all the HTML in HtmlTextWriter Object and from HtmlTextWriter Object we have simply dump the output the to the string builder. That’s it ….

Show Visitors Map On Your Website (Map Stats)

11. April 2009 AngryCoder Software Reviews Comments (0)
Geeks, have you ever think of displaying visitors map on your website or blog. My friend Al Pascual created a free tool that can integrate right in your website and start functioning. That tool is called Map Stats.The best thing about Map Stats is it is Open Source and will be soon available on Codeplex And integration is very very easy all you need to do is to copy/paste a single line of JavaScript.Here is how you can integrate it.
   1: <script type="text/javascript" src="http://mapstats.net/Stats.ashx?Width=300&Height=200"></script>
I recommend all the bloggers to have a look at that and use Map Stats as it is very handy yet very useful tool.

Storing/Retrieving Hierarchies In SQL Server Database

16. March 2009 AngryCoder SQL Server , TSQL Comments (0)
Hierarchies are one of the most important part of many applications. It can be in shape of categories, family tree, organization charts etc. Maintaining hierarchies in data source like XML is not a big deal but when it comes to the database like SQL Server which is consist of flat table in terms of storing data, then it become a challenge.To overcome this (which I am sure most of us did ), we use recursion. Implementing recursion is very easy and can be applied on both back-end (by using cursors) and front-end. But yet recursive operation can be a great mess if hierarchy grow larger. Lots of repetitive quires and n number of database connection can make your application way slow.So, the idea of the moment is to use the hierarchical data without using recursion. while searching for the solution I came across “Storing Hierarchical Data in a Database” by Gijs Van Tulder. In this article, the Dutch guy mention two method for the processing of Hierarchal data. One is the same recursion which we have discussed above and the other one is ‘modified preorder tree traversal' algorithm.
Modified preorder tree traversal :
To make you understand better let me quote what he mention in his article.We'll start by laying out our tree in a horizontal way. Start at the root node (‘Food'), and write a 1 to its left. Follow the tree to ‘Fruit' and write a 2 next to it. In this way, you walk (traverse) along the edges of the tree while writing a number on the left and right side of each node. The last number is written at the right side of the ‘Food' node. In this image, you can see the whole numbered tree, and a few arrows to indicate the numbering order.sitepoint_numberingWe'll call these numbers left and right (e.g. the left value of ‘Food' is 1, the right value is 18). As you can see, these numbers indicate the relationship between each node. Because ‘Red' has the numbers 3 and 6, it is a descendant of the 1-18 ‘Food' node. In the same way, we can say that all nodes with left values greater than 2 and right values less than 11, are descendants of 2-11 ‘Fruit'. The tree structure is now stored in the left and right values. This method of walking around the tree and counting nodes is called the ‘modified preorder tree traversal' algorithm.Sources : http://www.sitepoint.com/article/hierarchical-data-database/2/Note : Let me keep myself honest, the above two paragraphs and image is by Gijs Van Tulder so He deserve the credit of this content. I am just sharing the T/SQL implementation of this algorithm.I again strongly recommend you to read the article completely  before going onward.

Schema :

Ok to start, lets create a following tabletblCommentsID is of course the primary key, where as comments is the simple text. Left and Right are the indexes of the child records where as level will show us at what level this node belongs to. so that we can set the tab index and indentation where as Entity Id is to group the nodes because in this table hundred different nodes set. So in short, Entity Id is to separate the different node set in a single table.Following is the script of the table
   1: CREATE TABLE [dbo].[tblComments](
   2:     [Id] [numeric](18, 0) IDENTITY(1,1) NOT NULL,
   3:     [Comments] [nvarchar](2000) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
   4:     [Left] [int] NULL,
   5:     [right] [int] NULL,
   6:     [Level] [int] NULL,
   7:     [EntityId] [int] NULL,
   8:  CONSTRAINT [PK_tblComments] PRIMARY KEY CLUSTERED
   9: (
  10:     [Id] ASC
  11: )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
  12: ) ON [PRIMARY]

Add Record:

Now to add the record in this table, lets have a look at the following procedure
   1: CREATE PROCEDURE [dbo].[InsertComments]
   2:     @Comments nvarchar(2000),
   3:     @EntityId int,
   4:     @ParentId int = null
   5: AS
   6: BEGIN
   7:     Declare @Left int
   8:     Declare @Right int
   9:     Declare @Level int
  10:     declare @RightParent int
  11:     declare @rightParentOrig int
  12:     declare @leftParentOrig int
  13:
  14:     set @RightParent = null
  15:
  16:     if @ParentId is null
  17:     begin
  18:         set @Left = 1
  19:         set @Right = 2
  20:     end
  21:     else
  22:     begin
  23:         select @rightParentOrig = [right],@leftParentOrig =[left] , @Right = [right] + 1,@Left=[right],@Level=[Level]+1 from tblComments where id = @ParentId
  24:         set @RightParent =  @Right  + 1
  25:     end
  26:
  27:     UPDATE tblcomments
  28:     set
  29:     [right] = [right] + 2,
  30:     [left] = [left] + 2
  31:     where
  32:     [left] >=  @Left and entityId = @EntityId
  33:
  34:     UPDATE tblcomments
  35:     SET
  36:     [right] = [right] + 2
  37:     WHERE [left] < @leftParentOrig and [right] > @rightParentOrig
  38:
  39:     INSERT INTO [tblComments]([Comments],[Left],[right],[Level],[EntityId])
  40:      VALUES
  41:            (@Comments,@Left,@Right,@Level,@EntityId)
  42:
  43:     if @RightParent is not null
  44:         update tblComments set [right] = @RightParent where id = @ParentId
  45:
  46: END
Ok, now let me define the code line by lineFirst 15 : Well, these lines are quit easy to understand, we have declared some variables which we will use in next lines.Line no 16-24 : We are checking if the ParentId is null, then of course the node is the parent it self, that is why setting left to 1 and right to 2. But when the parent is specified, we need to set the right and left value according to the parent (+1 of the parent) and also need to +1 the level.Line no 27-37 : Consider a situation, where you have a tree completed and you want to add a node in the middle of the tree. These are the lines for that. Here, we are Creating space of the node by increasing the left and right values of the sibling nodes.Line no 39: This is the simple insert statement, where we are adding our record to the table with calculated right and left.Line no 43: In this statement, we are updating the right side of the parent node.Now Add some records using the above procedures, and do the select as following

Select Records:

   1: select * from tblComments where EntityId = 1
   2: order by [left] ,[right]
   3: -- 2nd option
   4: select * from tblComments where [left] >= 1 and [right] <= 10 and EntityId = 1
   5: order by [left] ,[right]
Both the above query will return the following result set.tblcommentsresultNow you can see the first record i.e id=30 is the parent record. So, the left value is 1 and the right is 10 and the level is 1. where as when you see the second record, it is the child of the first record that is why level is 2 and left is +1 greater then the parent and because all the records up to id=35 are it’s child so it has right index +1 greater then the last child.Now if you want to see the child of id=32 you can do as follows
   1: declare @left int,
   2: @right int,
   3: @EntityId int
   4:
   5: select @left= [left],  @right= [right],@EntityId =  EntityId from tblComments where Id = 32
   6:
   7: select * from tblComments where [left] >= @left and [right] <= @right and EntityId = @EntityId
   8: order by [left] ,[right]
In this way, you can exactly see the child nodes of each node.

Delete Records:

Now, lets see how can we remove the record from this table as hierarchy is depend upon the left and right index.
   1: CREATE PROCEDURE [dbo].[DeleteComments]
   2:     @CommentId int
   3: AS
   4: BEGIN
   5: Declare @Left int
   6: Declare @Right int
   7: declare @EntityId int
   8:
   9: select @Left = [left], @Right = [right], @EntityId = [EntityId] from tblComments
  10: where id = @CommentId
  11:
  12:
  13: delete from tblComments
  14: where id = @CommentId
  15:
  16: update tblComments
  17: set [left] = [left] - 2,
  18: [right] = [right] - 2
  19: where [left] >= @Left and entityId = @EntityId
  20:
  21:
  22: UPDATE tblcomments
  23:     SET
  24:     [right] = [right] - 2
  25:     WHERE [left] < @Left and [right] > @Right
  26:
  27: END
In Line no 9-10 : we are storing the left, right and entity of the record that will be deleted.In Line no 13-14 : delete the record from table.In Line no 16- end: updating the right and left values of the parent and sibling nodes by –2.

Conclusion:

This way, we can easily achieve the task of Hierarchal data without recursion. One more time, with full respect I like to give all the credit to Gijs Van Tulder. I have just made small modification in this to make it work according to me to.

Saving and Retrieving File Using FileStream SQL Server 2008

16. March 2009 AngryCoder .net , SQL Server , c# , TSQL Comments (0)

FileStream data type is a very important feature of SQL Server 2008 and gradually getting popular amongst developer for it’s feasibility. And in the past few days specially after “Configure SQL Server 2008 for File Stream” post. I received several feedbacks regarding the usage of FileStream with Ado.net and Frankly there is not much stuff available on Google for this topic.

In this post, I will guide you to use FileStream Data type in Ado.net. But before we start make sure you have configure your SQL Server 2008 instance to use File Stream Data type and for this you can read this post.

Once you finish with the Configuration execute the following script

   1: CREATE TABLE [dbo].[tbl_Files](
   2:     [Id] [uniqueidentifier] ROWGUIDCOL  NOT NULL,
   3:     [SystemNumber] [int] NOT NULL,
   4:     [SystemFile] [varbinary](max) FILESTREAM  NULL,
   5:     [FileType] [varchar](5) NULL,
   6: UNIQUE NONCLUSTERED 
   7: (
   8:     [Id] ASC
   9: )WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
  10: ) ON [PRIMARY] FILESTREAM_ON [FileStreamGroup1]
  11:  
  12: GO
  13:  
  14: ALTER TABLE [dbo].[tbl_Files] ADD  CONSTRAINT [DF_tbl_Files_Id]  DEFAULT (newid()) FOR [Id]

This will create a table with FileStream Data type. Notice the FileType field I have used here to determine the type of file which we will use when we were downloading the file.

Now that we have created a table, lets now move on to the Stored Procedures by which we will access this newly created table.

Security Setting:

Don’t get confused with the heading, there is no additional setting required. You need to do one of the two available options. Either you need to specify “Integrated Security = true” in Connection String or you need to implement Asp.net Impersonation. It is there because SQL Server 2008 will not allow un authenticated user or instance to read/modify the file.

Most of the developers usually aware of Integrated Security stuff but let me give a little detail about asp.net impersonation. Actually, it is a way to Authorize the Instance of your asp.net application on SQL Server by using Credential Information.

Following links will help you to understand or implement impersonation.

http://blogs.msdn.com/shawnfa/archive/2005/03/21/400088.aspx
http://blogs.msdn.com/saurabhkv/archive/2008/05/29/windowsidentity-impersonation-using-c-code.aspx
http://www.west-wind.com/WebLog/posts/1572.aspx

Add Procedure:

Lets create a procedure call it “”FileAdd” and past the following script.

   1: Create PROCEDURE [dbo].[FileAdd]
   2: @SystemNumber int,
   3: @FileType varchar(5),
   4: @filepath varchar(max) output
   5: AS
   6: BEGIN
   7:     -- SET NOCOUNT ON added to prevent extra result sets from
   8:     -- interfering with SELECT statements.
   9:     SET NOCOUNT ON;
  10:  
  11:     DECLARE @ID UNIQUEIDENTIFIER
  12:     SET @ID = NEWID()
  13:  
  14:     INSERT INTO [dbo].[tbl_Files]
  15:     ([Id],[SystemNumber],SystemFile,FileType)
  16:     VALUES (@ID ,@SystemNumber,CAST('' AS VARBINARY(MAX)),@FileType)
  17:     
  18:     select @filepath = SystemFile.PathName() from tbl_Files where Id = @ID
  19:  
  20:     
  21:  
  22: END

In the above procedure, we add new records in our table and just pass empty (null) to the FileStream field because we first want our SQL Server to create an empty file on NTFS location which we can access from our code behind by using the path which we have taken as Output Parameter here.

notice the SystemFile.PathName(), it is a new function introduced in SQL Server 2008 which will return the NTFS location of the file.

 

Get Procedure:

Create a procedure and call it “FileGet”

   1: CREATE PROCEDURE [dbo].[FileGet]
   2: @Id varchar(50)
   3: AS
   4: BEGIN
   5:      select  SystemFile.PathName(),FileType from tbl_Files where Id = @ID
   6: END

This is a simple stuff, we are returning PathName and FileType by specifying ID. Just to read the record.

Upload and Store:

To save the file in the file stream, we will use FileUpload control to upload the file and then save it to FileStream field. For that we have created a page and drag FileUpload control with an Upload button.

Now on the click event of the button write the following code. 

   1: byte[] buffer = new byte[(int)FileUpload1.FileContent.Length];
   2: FileUpload1.FileContent.Read(buffer, 0, buffer.Length);
   3:  
   4:  
   5: if (FileUpload1.FileContent.Length > 0)
   6: {
   7:     SqlConnection objSqlCon = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
   8:     objSqlCon.Open();
   9:     SqlTransaction objSqlTran = objSqlCon.BeginTransaction();
  10:  
  11:     SqlCommand objSqlCmd = new SqlCommand("FileAdd",objSqlCon,objSqlTran);
  12:     objSqlCmd.CommandType = CommandType.StoredProcedure;
  13:  
  14:     SqlParameter objSqlParam1 = new SqlParameter("@SystemNumber", SqlDbType.Int);
  15:     objSqlParam1.Value = "1";
  16:  
  17:     SqlParameter objSqlParam2 = new SqlParameter("@FileType", SqlDbType.VarChar,4);
  18:     objSqlParam2.Value = System.IO.Path.GetExtension(FileUpload1.FileName);
  19:  
  20:     SqlParameter objSqlParamOutput = new SqlParameter("@filepath", SqlDbType.VarChar, -1);
  21:     objSqlParamOutput.Direction = ParameterDirection.Output;
  22:  
  23:     objSqlCmd.Parameters.Add(objSqlParam2);
  24:     objSqlCmd.Parameters.Add(objSqlParam1);
  25:     objSqlCmd.Parameters.Add(objSqlParamOutput);
  26:  
  27:  
  28:     objSqlCmd.ExecuteNonQuery();
  29:  
  30:     string Path = objSqlCmd.Parameters["@filepath"].Value.ToString();
  31:  
  32:     objSqlCmd = new SqlCommand("SELECT GET_FILESTREAM_TRANSACTION_CONTEXT()", objSqlCon, objSqlTran);
  33:  
  34:     byte[] objContext = (byte[])objSqlCmd.ExecuteScalar();
  35:     
  36:  
  37:     SqlFileStream objSqlFileStream = new SqlFileStream(Path, objContext, FileAccess.Write);
  38:     
  39:     objSqlFileStream.Write(buffer, 0, buffer.Length);
  40:     objSqlFileStream.Close();
  41:  
  42:     objSqlTran.Commit();

Well, in the first two lines we have saved the uploaded file in byte and call this variable “buffer”.
As we are simply using ADO.net, that is why in line 7 and 8 we have created and open a connection. Where as it is worth to mention here, we need to use transaction when we want to do any operation on FileStream field that is why we have begin a new transaction in line no 9.

On line number 11 to 30, we have a simply setup command object and parameter stuff and then execute the procedure and save the output parameter in a variable called “Path”.

This new variable will contain the NTFS location of the file which is stored on SQL Server FileStream. It should be clear that, this file is empty yet as we have not stored any thing in it.

Now on line number 32 we have reused command object and this time we are executing a simple statement “GET_FILESTREAM_TRANSACTION_CONTEXT”. It is also a newly added feature in SQL Server 2008 which will return current transaction context to be used in the next few lines. Now, on line number 34 we have stored the output of the above statement in byte.

In line number 37, here is some thing new which is called “SqlFileStream”. It is a new class which you can find under “System.Data.SqlTypes”. It seems more like FileStream of “System.IO” but it should be cleared here that the file stored in FileStream field cannot be access using regular file stream object of “System.IO” we need to use SqlFileStream to access those files which are stored in FileStream field.

In line no 39 and on, we are writing the file with the content of uploaded file (Remember we have stored our uploaded file in bytes and call it “buffer”). and that’s it.

Read The Stored File:

We have finished with storing the file, now lets see how can we read this file back. To do this, Drag a Grid View and make it similar to the following 

   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") %>' Text="Get File"></asp:LinkButton>
   9:                </ItemTemplate>
  10:            </asp:TemplateField>
  11:        </Columns>
  12:    
  13:    </asp:GridView>

And bind the GridView using the following code. 

   1: protected void bindData()
   2: {
   3:     SqlConnection objSqlCon = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
   4:     objSqlCon.Open();
   5:  
   6:     SqlCommand objSqlCmd = new SqlCommand("Select * from tbl_Files", objSqlCon);
   7:     SqlDataAdapter objSqlDat = new SqlDataAdapter(objSqlCmd);
   8:     DataTable objdt = new DataTable();
   9:     objSqlDat.Fill(objdt);
  10:  
  11:     GridView1.DataSource = objdt;
  12:     GridView1.DataBind();
  13: }

Well, the above markup and the code is enough self explaining but the little important stuff to mention here is the link button. We will use the same link button to download the stored file. Lets quickly move on to the RowCommand implementation of the GridView. 

   1: protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
   2: {
   3:     if (e.CommandName == "GetFile")
   4:     {
   5:  
   6:         SqlConnection objSqlCon = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
   7:         objSqlCon.Open();
   8:         SqlTransaction objSqlTran = objSqlCon.BeginTransaction();
   9:  
  10:         SqlCommand objSqlCmd = new SqlCommand("FileGet", objSqlCon, objSqlTran);
  11:         objSqlCmd.CommandType = CommandType.StoredProcedure;
  12:  
  13:         SqlParameter objSqlParam1 = new SqlParameter("@ID", SqlDbType.VarChar);
  14:         objSqlParam1.Value = e.CommandArgument;
  15:  
  16:         objSqlCmd.Parameters.Add(objSqlParam1);
  17:         string path = string.Empty;
  18:         string fileType = string.Empty;
  19:  
  20:         using (SqlDataReader sdr = objSqlCmd.ExecuteReader())
  21:         {
  22:             while (sdr.Read())
  23:             {
  24:                 path = sdr[0].ToString();
  25:                 fileType = sdr[1].ToString();
  26:             }
  27:             
  28:         }
  29:         
  30:         objSqlCmd = new SqlCommand("SELECT GET_FILESTREAM_TRANSACTION_CONTEXT()", objSqlCon, objSqlTran);
  31:  
  32:         byte[] objContext = (byte[])objSqlCmd.ExecuteScalar();
  33:  
  34:  
  35:         SqlFileStream objSqlFileStream = new SqlFileStream(path, objContext, FileAccess.Read);
  36:  
  37:         byte[] buffer = new byte[(int)objSqlFileStream.Length];
  38:         objSqlFileStream.Read(buffer, 0, buffer.Length);
  39:         objSqlFileStream.Close();
  40:  
  41:         objSqlTran.Commit();
  42:         Response.AddHeader("Content-disposition", "attachment; filename=" + Path.GetFileName(path) + fileType);
  43:         // Here you need to manage the download file stuff according to your need
  44:         Response.ContentType = "application/octet-stream";
  45:  
  46:         Response.BinaryWrite(buffer);
  47:  
  48:  
  49:         
  50:     }
  51: }

Well, in the first 8 lines, we have created and opened a connection and then begin the transaction. from line no 10 to 28, we are setting the parameter stuff, executing the procedure and save the output in the two variable called “path” and “fileType”.

In line no 30 to 32, we are executing the the transaction context statement and then save the output the bytes. (Same we have done when we were writing the file)

In line no 35 to 40, we have used the same SqlFileStream and instead of writing, we are reading the file this time(notice line no 38) and save the content of the file to the bytes. Now we have file content in bytes, So we have now commit the transaction in line no 41.

In line no 42 and 44, we are setting the content type and specifying the file name with the extension. That is why, we have also saved file type in the database so that at the time of downloading we can make it available in its original state.

And in line no 46, we are simply writing the binary of the file to the browser so that it can be downloaded.

Conclusion:

I have tried my best to explain the integration of FileStream field with ADO.net, and I found this is an easy way to accomplish the task. You can download the VS 2008 solution which contain the complete source code along with procedures and table SQL.

Since, it is a new featured in SQL Server 2008 which is still in CTP by the time I am posting this stuff that is why we can expect some modifications in the method of reading and saving files using FileStream. If somebody face any challenge in the above code. Please feel to contact me.