The Angry Coder

I have been using Authorize attribute heavily to manage user authorizations, but at times just Authorize attribute is not enough. For an instance, I want user to access the Edit page of any entity which he created. In other words I don’t want him to edit records created by other users.

We cannot do this using Authorize only because it is design to limit access to an action regardless of what data is being passed to it. Thus, in this case you can maintain CreatedUser field in the record table and check on the Action if the logged in user is authorize to do this edit. Here is the code for that.

if (myrecord.OwnerId != User.Identity.Name)
{
   return new HttpUnauthorizedResult();
}

You can return HttpStatusCodeResult(403) too but that will only display the default access denied page of IIS, which is not we want and this is where “HttpUnauthorizedResult” comes handy.

Consider a case when you have single model which is bind to multiple views. For example, UserInformation model bind to “Create” and “Edit” view. Now in “Create” view, I want to “Password” field as required but at the same time I want it to be optional on “Edit” view.

It means, In “Edit” view, If user provides “Password” then change it otherwise don’t update the “Password” field.

This is why it is important to create ViewModels, which gives you freedom to have different fields, validations etc for every view.

Now to achieve this goal in the given scenario, we need to make two tweaks.

Client Side

To disable client side validation, we need to disable it by force.

@Html.EditorFor(model => model.Password, new { htmlAttributes = new {  @data_val = "false" , @class = "form-control"} })

Notice the @data_val= “false”. It will disable the validation on this field.

Server Side (In Action)

When the model is validated on the post action, ModelState.IsValid will always return false because password is not provided. Here we have to provide the current password to the model and Re-validate the model.

var userObj = db.Users_Info.Where(a => a.Id == users_Info.Id).FirstOrDefault();

if (String.IsNullOrEmpty(users_Info.Password))
{
    users_Info.Password = userObj.Password;
}

ModelState.Clear();
TryValidateModel(users_Info);

Let me explain, first we retrieve current information saved in the database which we are using later to assign to current model if password is not provided. The last two lines actually reset the ModelState to return updated result on ModelState.IsValid.

Angry Coding   

From the last few days, I was ignoring an error that keep coming at the compile time. I spent some two hours on it before but didn’t get it work. The error is quit confusing and of course difficult to manage.

'ApplicationSettingsBase' is ambiguous in the namespace 'System.Configuration'

'MailMessage' is ambiguous in the namespace 'System.Net.Mail'

And there are couple of other similar errors that is pointing to some ambiguous references in my project.  The confusing part is that the MailMessage object throws similar error when you are importing the old and new email namespace.

For example,

Imports System.Web.Mail
Imports System.Net.Mail

So if you are only encountering ambiguous problem in MailMessage object. It is more possible that you have define both the namespaces in your code behind which is actually confusing the compiler about your referencing object.

The quick solve for this problem is that remove Imports System.Web.Mail and it should work smooth. But with me, I never used the old asp.net mail namespace in my project.

Then I start looking at my references and luckily I found the problem there. Follow the steps below to investigate the issue

1. Go to your project

2. Then references

3. Right click on “System” and see properties. it should point to the following path

x:\Windows\Microsoft.NET\Framework\v2.0.50727\System.dll

Where x is name of your operating system directory. This was the problem with my project. I had my operating system install on “D” drive and some how it is pointing to “C” drive which is the root cause of this problem.

After that I verify all my references and found 5 –6 assemblies that are pointing to wrong path and get it worked.

Also note, the problem can occur in any type of project either it is website , web application etc.

Introduction:

In this post, I will explain you how can we get the countries name filled in any collection using .net without using any database.

It is a regular task, which we all as developers did some past day but the difference is we used database table or xml file to hold the country names. But .net framework provide us with all the countries information in Globalization namespace.

So, here is the code for that

Dictionary<string,string> objDic = new Dictionary<string,string>();

foreach (CultureInfo ObjCultureInfo in CultureInfo.GetCultures(CultureTypes.SpecificCultures))
{
    RegionInfo objRegionInfo = new RegionInfo(ObjCultureInfo.Name);
    if (!objDic.ContainsKey(objRegionInfo.EnglishName))
    {
        objDic.Add(objRegionInfo.EnglishName, objRegionInfo.TwoLetterISORegionName.ToLower());
    }
}

var obj = objDic.OrderBy(p => p.Key );
foreach (KeyValuePair<string,string> val in obj)
{
    ddlCountries.Items.Add(new ListItem(val.Key, val.Value));
}

Explanation:

Notice that, we have used typed dictionary object to store the name and the values of the countries.

Then, we use CultureInfo.GetCultures to get the cultural information of the countries.

Later on, we use RegionInfo to get the regional information of that  culture.

Since, there can be multiple cultures of the same country that is why there is a condition which check either the country is already added in dictionary. If not, then simply add the country name and country two letter name. (Note : We are treating the two letter country name as the value)

After the loop, I used some LinQ stuff to sort county names, and then iterate through the returned object to add the values in drop down list.

That’s it. Now you are not only limited to show the English name of the country but you can also show the native name. For example, the name of my country in English is “Islamic Republic of Pakistan” but the native name is پاکستان.

Also, you can get the following country information using RegionInfo

Some developers are habitual of using country id along with the country name. if they still want to use some id to save the country information they can use the GeoId property of the RegionInfo.

In this post, I will explain you how can we show Loading message in asp.net ajax without using Update Progress. Now some one may asked, why do I want to skip Update Progress ?

Well, there can be several reasons for this, fist of all you have to work on every single page, and on every update panel to get the update progress working.

There are basically three methods of meeting this requirement.

1. Using Master Pages : A very smart way, but not all of us are using them .. right ?
2. Extending Page Class  : A little harder but to me it is very elegant way.
3. Extending Script Manager : Similar to the page class one, but implementation is comparatively simple.

The Basics:

Before I start with exploring the different approaches let me first create a ground by showing what things will be involve in creating a loading message.

I want the background to be grayed and displayed a simple loading text at the top, for that we need a style sheet, which will apply to the loading message div.  Create a stylesheet and call it style.css

.ModalProgressContainer
{
    z-index: 10005;
    position: fixed;
    cursor: wait; 
    top:0%; 
    background-color: #ffffff; 
    filter: alpha(opacity=50);
    opacity: 0.5;
    -moz-opacity: .5; 
    height: 100%;
    width: 100%;
    text-align: center; 
    
    } 
.ModalProgressContent
{
    padding: 10px; 
    border: solid 0px #000040; 
    font-weight: bold; 
    background-color:#ffffff;
    margin-top:300px;
} 

Now lets read and understand the following script.

var prm = Sys.WebForms.PageRequestManager.getInstance();
prm.add_initializeRequest(InitializeRequest);
prm.add_endRequest(EndRequest);

// ----------------------------- //
// the below script will be saved in JS File, create a JS file and call it ajaxload.js and save the following script

function InitializeRequest(sender, args) {

    if (document.getElementById('ProgressDiv') != null)
       $get('ProgressDiv').style.display = 'block';
    else
        createContorl();
}

function EndRequest(sender, args) {

    if (document.getElementById('ProgressDiv') != null)
        $get('ProgressDiv').style.display = 'none';
    else
        createContorl();
}

function createContorl() {
    var parentDiv = document.createElement("div");
    parentDiv.setAttribute("class", "ModalProgressContainer");
    parentDiv.setAttribute("Id", "ProgressDiv");
 

    var innerContent = document.createElement("div");
    innerContent.setAttribute("class", "ModalProgressContent");
    var img = document.createElement("img");

    img.setAttribute("src", "/Images/Images/Loading.gif");

    var textDiv = document.createElement("div");
    textDiv.innerHTML = 'Loading....';

    innerContent.appendChild(img);
    innerContent.appendChild(textDiv);

    parentDiv.appendChild(innerContent);

    document.body.appendChild(parentDiv);

}

Notice,in the first three lines. We are getting the instance of PageRequestManager and then defining InitilizeRequest and EndRequest functions to display or hide the loading div. Where as, in createControl function we are simply writing DHTML, to be more specific there is no HTML of the loading div in our markup. So, we are writing that from JavaScript.

Also, note the that I have break down this script into two part by using comments. First is the declaration and second is definition of the functions.

note: The definition will take place on a seperate JS file where as the declaration need to be made in the page, under body markup.  Now we are all set to explore different approaches.

Using Master Pages :

A very simple approach, all you need to do is open your master page and paste the following lines in the head section.

<link href="style.css" rel="stylesheet" type="text/css" />
<script type="text/javascript" src="ajaxload.js"></script>

And in body, after form tag create a script section and paste the following JavaScript.

var prm = Sys.WebForms.PageRequestManager.getInstance();

prm.add_initializeRequest(InitializeRequest);
prm.add_endRequest(EndRequest);

Notice it is the same declaration section which we have discussed above and that’s it you are done. All the content form of your web application should now display loading div on each partial postback.

Extending Page Class  :

For this, create a class file and call it ajaxPage and inherit it from System.Web.UI.Page and write the following code.

public class ajaxPage : Page
{
    protected override void OnLoad(EventArgs e)
    {
        //Include CSS File
        Page.Header.Controls.Add(new LiteralControl("<link href='style.css' rel='stylesheet' type='text/css' />"));


        //Include JS file on the page
        ClientScript.RegisterClientScriptInclude("ajaxload", ResolveUrl("~/ajaxload.js"));

        //Writing declaration script 
        String script = "var prm = Sys.WebForms.PageRequestManager.getInstance();";
        script += "prm.add_initializeRequest(InitializeRequest);";
        script += "prm.add_endRequest(EndRequest);";

        ClientScript.RegisterStartupScript(typeof(string), "body", script, true);

        base.OnLoad(e);
    }

}

Well, we have simply extend the System.Web.UI.Page into our own class and override OnLoad function to include the JS file and write the declaration markup.

Now, on the page code behind where you want to implement Loading message change the inherit namespace from System.Web.UI.Page to ajaxPage (make sure you namespace).

Extending Script Manager :

Now instead of extending page class we will extend Script Manager control and for that create a new class file and call it ScrtipManagerExt and write the following code.

public class ScriptManagerExt : ScriptManager
{
    protected override void OnLoad(EventArgs e)
    {

        //Include CSS File
        Page.Header.Controls.Add(new LiteralControl("<link href='style.css' rel='stylesheet' type='text/css' />"));

        RegisterClientScriptInclude(this, typeof(Page), "ajaload", ResolveClientUrl("~/ajaxload.js"));

        String script = "var prm = Sys.WebForms.PageRequestManager.getInstance();";
        script += "prm.add_initializeRequest(InitializeRequest);";
        script += "prm.add_endRequest(EndRequest);";

        RegisterStartupScript(this, typeof(Page), "ajaxtest", script, true);
        base.OnLoad(e);
    }
}

Almost the same thing we did in extend page approach, only the implementation will be change. Instead of using the old Script Manager we will use our new one. the include directive and markup will look like as below.

<%@ Register Assembly="Assembly" Namespace="namespace" TagPrefix="cc1" %>
<cc1:ScriptManagerExt ID="ScriptManagerExt1" runat="server">
</cc1:ScriptManagerExt>

That’s it we are done. I tried to make it simpler and show you every possible way I know of doing this task. Again, any approach selection will be on you and your project type. You can also download  the VS 2008 project file.

Few days ago, when I was trying to put validation controls on a form which is at the bottom of the page. I noticed that each time Asp.net validation controls executed it reset the scroll position to top and the end user see no messages until page scroll back to the old position. Irritated :)

Problem:

So, In this post I will demonstrate you how to maintain the scroll position of asp.net validation controls on a page. To start with an example, lets create a form like below

<div>
     <p>

 </p>
 <p>
     &nbsp;</p>
 <p>
     &nbsp;</p>

         <p>
             &nbsp;</p>

         <p>
             &nbsp;</p>
         <p>
             &nbsp;</p>
         <p>
             &nbsp;</p>
         <p>
             &nbsp;</p>
         <p>
             &nbsp;</p>
 <p>
     &nbsp;</p>
 <p>
     &nbsp;</p>
 <p>
     &nbsp;</p>
     <table class="style1">
         <tr>
             <td>
                 Name</td>
             <td>
                 <asp:TextBox ID="txtName" runat="server" autocomplete="off" Width="200"></asp:TextBox>
                 <asp:RegularExpressionValidator ID="revName" runat="server" 
                     ControlToValidate="txtName" Display="None" 
                     ErrorMessage="Please enter a valid name" 
                     ValidationExpression="(^([0-9-a-z-A-Z\\s+?\\.+?\\(+?\\)+?])+$)" 
                     ValidationGroup="grpTop"></asp:RegularExpressionValidator>
                     <asp:RequiredFieldValidator ID="rfvName" runat="server" 
                     ControlToValidate="txtName" Display="None" ErrorMessage="Please enter a name." 
                     SetFocusOnError="true" ValidationGroup="grpTop"></asp:RequiredFieldValidator>
             </td>
         </tr>
         <tr>
             <td>
                 Email Address</td>
             <td>
                 <asp:TextBox ID="txtUsername" runat="server" autocomplete="off" Text="" 
                     Width="200"></asp:TextBox>
                 <asp:RequiredFieldValidator ID="rfvEmailAddress" runat="server" 
                     ControlToValidate="txtUsername" Display="None" 
                     ErrorMessage="Please enter a valid email address." ValidationGroup="grpTop"></asp:RequiredFieldValidator>
                 <asp:RegularExpressionValidator ID="revEmail" runat="server" 
                     ControlToValidate="txtUsername" Display="None" 
                     ErrorMessage="Please key in a valid email address." SetFocusOnError="true" 
                     ValidationExpression="^([a-zA-Z0-9_'+*$%\\^&amp;!\\.\\-])+\\@(([a-zA-Z0-9\\-])+\\.)+([a-zA-Z0-9:]{2,4})+$" 
                     ValidationGroup="grpTop"></asp:RegularExpressionValidator>
                 <asp:CustomValidator ID="valEmailAlreadyExists" runat="server" Display="None" 
                     ErrorMessage="Email address already exists" ValidationGroup="grpTop"></asp:CustomValidator>
             </td>
         </tr>
         <tr>
             <td>
                 Date Format</td>
             <td>
                 <asp:DropDownList ID="ddlDateFormat" runat="server" Width="200px">
                     <asp:ListItem>Select</asp:ListItem>
                     <asp:ListItem Text="dd/MM/yyyy" Value="dd/MM/yyyy">dd/MM/yyyy</asp:ListItem>
                     <asp:ListItem Text="MM/dd/yyyy" Value="MM/dd/yyyy">MM/dd/yyyy</asp:ListItem>
                     <asp:ListItem Text="dd/MM/yy" Value="dd/MM/yy">dd/MM/yy</asp:ListItem>
                     <asp:ListItem Text="MM/dd/yy" Value="MM/dd/yy">MM/dd/yy</asp:ListItem>
                 </asp:DropDownList>
                 <asp:RequiredFieldValidator ID="rfvDateFormat" runat="server" 
                     ControlToValidate="ddlDateFormat" Display="None" 
                     ErrorMessage="Please select date format." InitialValue="Select" 
                     SetFocusOnError="true" ValidationGroup="grpTop"></asp:RequiredFieldValidator>
             </td>
         </tr>
         <tr>
             <td>
                 &nbsp;</td>
             <td>
                 <asp:CheckBox ID="cbIsAdmin" runat="server" Checked="false" 
                     Text="Administrator?" />
                 &nbsp;<asp:CheckBox ID="cbResetPW" runat="server" Checked="false" 
                     Text="Reset Password" />
             </td>
         </tr>
         <tr>
             <td>
                 &nbsp;</td>
             <td>
                 <asp:Button ID="Button1" runat="server" Text="Submit Group 1"  ValidationGroup="grpTop"
                     onclick="Button1_Click" />
                 <asp:ValidationSummary ID="ValidationSummary1" runat="server" 
                     EnableClientScript="true" HeaderText="Fix the following issues :" 
                     ValidationGroup="grpTop" />
             </td>
         </tr>
         <tr>
             <td>
                 &nbsp;</td>
             <td>
                 &nbsp;</td>
         </tr>
     </table>
</div>

Notice that <p> tag which I have given in the above snippet to keep my form at the bottom of the page so that the scroll position problem can easily be demonstrated.

When you run the above snippet, you will realize that the page scroll position will lost as soon as you want to submit the form. If you try the page directive System.Web.Ui.Page.MaintainScrollPositionOnPostBack. Noting will change because by using this property Asp.net engine will take care of scroll position after post back. But we want it on client script. It means, we need to modify the mechanism on which asp.net validation controls executed.

To start with the understanding, I came across a very good article “Understanding ASP.NET Validation Library” by DeepakRaghavan. Which gives me the understanding of two methods. Page_ClientValidate and WebForm_OnSubmit and ultimately I need to modify them and bear in mind that these function will be written inside form tag not in title.

The idea is to use the bookmark to maintain the scroll bar. So lets modify both the functions respectively.

Page_ClientValidate:

   1: var bookMark = "#OtherBookMark";

   2: function Page_ClientValidate(validationGroup)

   3: {

   4:   

   5:   Page_InvalidControlToBeFocused = null;  

   6:   if (typeof(Page_Validators) == "undefined") {  

   7:   return true;  

   8:   }  

   9:   var i;  

  10:   for (i = 0; i < Page_Validators.length; i++) {  

  11:   ValidatorValidate(Page_Validators[i], validationGroup, null);  

  12:   }  

  13:   ValidatorUpdateIsValid();  

  14:   ValidationSummaryOnSubmit(validationGroup);  

  15:   Page_BlockSubmit = !Page_IsValid;  

  16:   

  17:   if (validationGroup == "grpTop")

  18:   {

  19:       bookMark = "#addForm";

  20:   }

  21:   else

  22:   {

  23:       bookMark = "#OtherBookMark";

  24:   }

  25:   return Page_IsValid;  

  26: }

Description:

Line No 1.       A variable that will hold the bookmark name

Line No 2-14   The default function implementation (We have simple nothing to do with it… simply copy / paste)

Line No 15- 22 Since we can have multiple forms on a page, that is why it is better to keep track that which validation group is called and decide the bookmark name accordingly.

Now instead of modifying WebForm_OnSubmit, let’s first create a following function

SubmitAction:

   1: function SubmitAction() {

   2: if (typeof(ValidatorOnSubmit) == "function" && ValidatorOnSubmit() == false)

   3:   {

   4:           var hashIndex = location.href.indexOf("#");

   5:           

   6:           if (hashIndex > -1) 

   7:           {

   8:               var loc = location.href.substring(0,hashIndex);

   9:               location.href = loc + bookMark;

  10:           }

  11:           else

  12:           {

  13:               location.href = location + bookMark;

  14:           }

  15:           

  16:           return false;

  17:   }

  18:   else

  19:   {

  20:       return true;

  21:   }

  22: }

Description:

Well, the function is very simple and don’t really need line by line commentary.
We are checking if the validation is fail, set the bookmark. other wise just let it go.

WebForm_OnSubmit:

Now we will call the above SubmitAction function inside WebForm_OnSubmit. To inject this function you need to write the following lines on the Page_Load

   1: if (!Page.ClientScript.IsOnSubmitStatementRegistered("keySubmitAction"))

   2: {

   3:     Page.ClientScript.RegisterOnSubmitStatement(this.GetType(), "keySubmitAction", "return SubmitAction();");

   4: }

System.Web.UI.Page.ClientScript.RegisterOnSubmitStatement is actually used to inject your script inside WebForm_OnSubmit. To be more specific, the first lines will be yours :).

and if you notice the Line No : 3 I used return statement which means as soon as WebForm_OnSubmit will execute my function (SubmitAction) will run first and then return the execution out… no more processing on WebForm_OnSubmit.

Now when you look at the view source of your browser you will see some thing similar to the following.

Ok, now we only need to setup our bookmark.

Just give the id “addForm” to the table or div inside which the validation summary control is placed. that’s it.  However, you can download the VS 2008 Solution from here.

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.

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

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.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 follows8e7af927-cc7e-4515-8409-d94566246de8.jpga3de6abb-382f-484c-822c-7f93e0ede0c7.jpg4ad64bf1-ea6e-4228-bdc0-300a0cd90f5a.jpgThe 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.

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.