Category: ASP.NET Page 2 of 7

Category for ASP.NET

Yield keyword in .NET

On May 20, 2012

I believe some of you already know about this but for me I never used it. Yield keyword has been existed since .NET 2.0 so I decided to look up of what it does and try to understand it

Based on MSDN

Yield is used in an iterator block to provide a value to the enumerator object or to signal the end of iteration, it takes one of the following form

Based on my understanding

Yield is a concatenation for a collection, or in SQL we normally use UNION

Yield break; is used to exit from the concatenation (remember it is not used to skip !)

One practical sample that I can think of is to get the enumerable of exception from inner exception (e.g stack trace)

sample code

Code Snippet

class Program
    {
        ///<summary>
        /// simple function to return IEnumerable of integer
        ///</summary>
        ///<returns></returns>
        private static IEnumerable<int> GetIntegers()
        {
            for (int i = 0; i <= 10; i++)
                yield return i;
        }
        ///<summary>
        /// simple function to return collection of class
        ///</summary>
        ///<returns></returns>
        private static IEnumerable<MyClass> GetMyNumbers()
        {
            for (int i = 0; i <= 10; i++)
                if (i > 5)
                    yield break;
                else
                    yield return new MyClass() { Number = i };
        }
        internal class MyClass
        {
            public int Number { get; set; }
            public string PrintNumber
            {
                get {
                    return “This is no “ + Number.ToString();
                }
            }
        }
        static void Main(string[] args)
        {
            Console.WriteLine(“Simple array of integer”);
            foreach (var number in GetIntegers())
                Console.WriteLine(number.ToString());
            Console.WriteLine();
            Console.WriteLine(“Collection of classes”);
            foreach (var myclass in GetMyNumbers())
                Console.WriteLine(myclass.PrintNumber);
            Console.ReadLine();
        }
    }

Output

Simple array of an integer
0
1
2
3
4
5
6
7
8
9
10Collection of classes
This is no 0
This is no 1
This is no 2
This is no 3
This is no 4
This is no 5

ModelState Errors in MVC through JSON

By fransiscuss

On May 15, 2012

In ASP.NET, ASP.NET MVC

Normally, when you used HttpPost/Form submission to post the view through the controller then you can have the model validation applied automatically through @Html.ValidationSummary()

But how do you get the ModelState errors through Json? You can still use LINQ to get the model errors from the ModelState and pass it through JSON

Code Snippet

public ActionResult JsonRegister(MemberModel.RegistrationModel model)
        {
            string error = string.Empty;
            if (!ModelState.IsValid)
            {
                IEnumerable<System.Web.Mvc.ModelError> modelerrors = ModelState.SelectMany(x => x.Value.Errors);
                foreach (var modelerror in modelerrors)
                {
                    error += modelerror.ErrorMessage + “\n”;
                }
            }
            return Json(new { success = false, errors = error }, JsonRequestBehavior.AllowGet);
        }

Delayed Script/Waiting in Javascript

By fransiscuss

On November 30, 2011

In ASP.NET, Javascript

I was struggling in finding out of how to make a simple delegate like in AJAX request through javascript. It takes me a few days to figure this out

Basically the problems are:

-I need to execute a piece code of javascript after getting the ticket from web service function

-The webservice function might not be responding to the first request because it waits for the state of the other external component

-The webservice will give the response when the external component is ready

-The client does not know when the external component is ready, neither the web service. But it wil be ready within 1-5 minutes which again depending external component

Possible Solution:

-Using the setTimeOut(function(){acquireTicket();}, 300000) will cause the application to wait for 5 mins before calling the web service , this approach will slowing down the user experience and waste of time because the external component can be ready earlier than 5 mins

-Using the while loop is not good because it makes the browser freezing while waiting and it will wasting the processing power because of the looping

Recommended Solution:

-Recall the function by itself using setTimeout Function using parameter to indicate whether it should go out of the loop or not

-The web service will be checked for every 2 seconds to check the response from the external component. Once the external component is ready then it will move on to execute the next line of code

–

Access javascript object properties with invalid character

By fransiscuss

On November 17, 2011

In ASP.NET, Javascript

ParseJSON returning you an object from your AJAX Call, the problem that I have is my object properties has invalid character (e.g “#”)

Assuming jsonData is my variable that contains the following information

I’d like to grab the property of “#innerxml”

Normally I can do this to get the property of an object but in this case I can’t due to invalid character

(jQuery.parseJSON(jsonData)[0]).#innerxml

So How do I access an object which has properties where one of the property name is using an invalid character (e.g “#”)

I can access with the following style

(jQuery.parseJSON(jsonData)[0])[‘#innerxml’]

Remapping svc extension in IIS 7 extension handlers

By fransiscuss

On November 8, 2011

In .NET, ASP.NET, Others

If you open your WCF/ svc file in your localhost through browser and it just display blank page then what might happen is you don’t have handler associated with svc extension

To verify it, go to your IIS and go to IIS Handler Mappings and try to find an svc extension entry, but if you couldn’t find extension SVC exists on the list, then you can remap/re-add the svc extension by running

C:\Windows\Microsoft.NET\Framework64\v3.0\Windows Communication Foundation\ServiceModelReg.exe –i

*if you are still using 32 bit then you just need to replace Framework64 with Framework

Simple Collapsible Panel using JQuery

By fransiscuss

On October 26, 2011

In ASP.NET, Javascript

I found a simple collapsible panel developed by a guy called Darren Ingram and I’d definitely recommend it to anyone wanted to implement collapsible panel. His Jquery implementation of collapsible panel is very simple. It just need 2 files (diQuery-collapsiblePanel.js and diQuery-collapsiblePanel.css – where the css classes can even be integrated to your own css class). I prefer this implementation because it’s just a div implementation and the JQuery script will be hooked up to the div elements (where the class name is collapsibleContainer) upon the page loaded. Simple and lightweight in comparison to the collapsible panel of AJAX toolkit (http://www.asp.net/ajaxLibrary/AjaxControlToolkitSampleSite/CollapsiblePanel/CollapsiblePanel.aspx)

the source code for the collapsible panel by Darren Ingram can be downloaded from his website (http://www.darreningram.net/pages/examples/jQuery/CollapsiblePanelPlugin.aspx)

Using Disposable object

By fransiscuss

On February 18, 2011

In .NET, C#

First method is to use the “Using” keyword which is quite clean and simple

using (IDisposable obj = new DataTable())
{
//do your logic with obj variable
}

Second method is to use Try and finally keyword

IDisposable obj = null;

try
{
obj = new DataTable();
}
finally
{
if (obj != null)
{
obj.Dispose();
}
}

Remove UTF8 BOM Character from the file

By fransiscuss

On February 18, 2011

In .NET, C#

Normally when you have a UTF8 encoded file then it might have BOM character that will be rendered when you read it using filestream even though when you open the file with the notepad it doesn’t have that character.

I’ve created a function to remove the BOM character from the file

private void removeBoms(string filePattern, string directory)
{
try
{
foreach (string filename in Directory.GetFiles(directory, filePattern))
{
var bytes = System.IO.File.ReadAllBytes(filename);
if (bytes.Length > 2 && bytes[0] == 0xEF && bytes[1] == 0xBB && bytes[2] == 0xBF)
{
System.IO.File.WriteAllBytes(filename, bytes.Skip(3).ToArray());
}
}

MessageBox.Show(“Files have been processed completely!”);
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
//uncomment this for recursive
//foreach (string subDirectory in Directory.GetDirectories(directory))
//{
//    removeBoms(filePattern, subDirectory);
//}
}

How to call it

private void btnProcess_Click(object sender, EventArgs e)
{
string extension = txtExtensions.Text;

if (extension.Trim().Length > 0 || folderBrowserDialog1.SelectedPath.Trim().Length > 0)
{
if (!extension.StartsWith(“*.”))
{
extension = “*.” + extension;
}

//just process the html files
removeBoms(extension, folderBrowserDialog1.SelectedPath);
}
else
{
if (extension.Trim().Length == 0)
{
txtExtensions.Focus();
MessageBox.Show(“Please specify the extension files”);
}
else if (folderBrowserDialog1.SelectedPath.Trim().Length == 0)
{
MessageBox.Show(“Please select target folder”);
}
}

}

Tag Replacement using Regex in .NET

By fransiscuss

On January 28, 2011

In C#

This snippet of code shows how to do Synchronisation or HTML tag replacement

-My problem is i want to synchronise of tags between 2 HTML document

Issue

-Source.htm

my source.htm has this tag

<xml id=“STATIC_CRITERIA_“>
  <fields>
    <field fieldID=“OPEN_FLAG“ displayType=“checkboxGroup“ searchType=“checkboxGroup“ underlyingType=“int“ />
    <field fieldID=“PARTITION“ displayType=“dropdown“ searchType=“profile“ profileID=“SU_PARTITIONS“ underlyingType=“int“ />
    <field fieldID=“TEMPLATE_IND“ displayType=“checkbox“ searchType=“checkbox“ underlyingType=“int“ />
    <field fieldID=“INCLUDE_DELETED“ displayType=“checkbox“ searchType=“checkbox“ underlyingType=“string“ />
  </fields>
</xml>

-Target.htm has this tag

<xml id=“STATIC_CRITERIA_“>
</xml>

So now the problem is how do I fill the gap in XML tag in target.htm with the value from mySource.htm. We can do this using regex and it’s very simple

  string originalDocument = Load(“c:\\MySource.htm”);
                string syncDocument = Load(“c:\\Target.htm”);
 
                MatchCollection mc = Regex.Matches(originalDocument, “<xml([ ]?.*?)>(.*?)</xml>”, RegexOptions.Singleline | RegexOptions.IgnoreCase);
 
                foreach (Match m in mc)
                {
                    string token = “<xml{0}>”;
                    syncDocument = Regex.Replace(syncDocument, String.Format(token, m.Groups[1].Value) + “(.*?)</xml>”,
                                                               String.Format(token, m.Groups[1].Value) + m.Groups[2].Value + “</xml>”,
                                                               RegexOptions.Singleline | RegexOptions.IgnoreCase);
                }

MatchCollection is used to return all the instances of that regular expression (e.g you might have multiple XML tags with different ID)

What does this tag means

“<xml([ ]?.*?)>(.*?)</xml>”

([ ]?.*) means that I don’t care whatever after it (e.g it can be ID or attributes etc). this is the first parameter that we stored on variable

(.*?) means that whatever inside the tag are captured into the second parameter that we stored on variable

You can access the first variable (e.g any attributes after the XML) by doing

m.Groups[1].Value

you can access the value inside the xml bracket by using

m.Groups[2].Value

so what contains in

m.Groups[0].Value

it contains the whole xml tag that we extracted using regex

then we can use regex.replace method to replace the tag in target html. When you replace the tag you need to replace the whole xml tag. You can’t just replace the inner part of it

   foreach (Match m in mc)
                {
                    string token = “<xml{0}>”;
                    syncDocument = Regex.Replace(syncDocument, String.Format(token, m.Groups[1].Value) + “(.*?)</xml>”,
                                                               String.Format(token, m.Groups[1].Value) + m.Groups[2].Value + “</xml>”,
                                                               RegexOptions.Singleline | RegexOptions.IgnoreCase);
                }

Enter button in TextBox ASP.NET

By fransiscuss

On August 17, 2010

In ASP.NET, Javascript, VB.NET

This article is demonstrating how to wire up an enter key into a textbox. For example you have a search text box where you press enter then it will click go button and at the same page you have another textbox where you want to do another button click when you press the enter which means it’ is not necessary to post the page. This java script is used to capture the key event of enter and execute the LinkButton and ASP.NET button Click Event on the server side. Please add this javascript to your javascript common library or add this to your master page. This piece of code works in Firefox as well


function ButtonKeyPress(evt, thisElementName)
{
    if(evt.which || evt.keyCode)
    {
        if ((evt.which == 13) || (evt.keyCode == 13))
        {
            // alert('post back href: ' +document.getElementById(thisElementName).href);

            if (typeof document.getElementById(thisElementName).href != 'undefined')
            {
                location = document.getElementById(thisElementName).href;
            }
            else
            {
                document.getElementById(thisElementName).click();
            }
            return false;
        }
    }
    else
    {
        return true;
    }
}

And add this to your .NET code behind on the page load

 Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
         If Not Page.IsPostBack Then


            If (User.Identity.IsAuthenticated) Then
                Response.Redirect("frmTimeMain.aspx")
            End If

            txtGUID.Attributes.Add("onkeydown", "ButtonKeyPress(event, '" + lnkSubmit.ClientID + "')")
            txtPassword.Attributes.Add("onkeydown", "ButtonKeyPress(event, '" + lnkSubmit.ClientID + "')")
          End If
    End Sub