C#

  • How to fix WebResource.axd JavaScript errors appearing when using asp.net routing

    I had an issue with one of our asp.net 4.0 websites recently. The site was using web forms, routing and had .net validation controls in use. Everything worked great until I used the validation controls and discovered that I was getting 2 JavaScript errors on every page that used these controls.

  • How to read from and write to the web.config file using C#

    To read from a Web.Config file using C# is very easy to do. Let's say we have an appSettings tag in our Web.Config that holds the website title. Inside in our web.config you would have something like this:

    To get .net to read this value all you need to do is add this to your code behind page on your site. Be sure to add the System.Web.Configuration namespace as this is not added by default.

    using System.Web.Configuration;

    //read in the SiteName tag from web.config

    string MySiteName = WebConfigurationManager.AppSettings["SiteName"];

    If you want more details on how to read from web.config please see my earlier post here

    You might also want to write to your web.config file to allow the end user to update this data. To do this you must ensure that the Network Service user (or the ASP.NET user on WinServer 03 or earlier) has modify permissions on your website root folder.

    Without the correct permission you will get the following error if you try to add the code below:
    An error occurred loading a configuration file: Access to the path 'c:\inetpub\wwwroot\yourwebsitefolder\py39wsfg.tmp' is denied.

    Assuming you have setup the correct permissions this code below will allow your web app to write to the web.config file.

    //update the SiteName tag in web.config with a new value

    Configuration config = WebConfigurationManager.OpenWebConfiguration("~");

    config.AppSettings.Settings["SiteName"].Value = "New Site Name Value";

    config.Save(ConfigurationSaveMode.Modified);

    ConfigurationManager.RefreshSection("appSettings");

  • How to use a JQuery UI modal box with asp.net

    View Demo | Download Source

    I was recently asked to look into making a JQuery UI dialog box (aka a modal box) work with asp.net. I thought it would be straight forward but as with anything in asp.net it turned out to be a little bit trickier than I had initially thought. Part of the problem was that I wanted to put the dialog box on an asp.net submit button and depending on the user's choice either submit the page or cancel the action.

    Thankfully I stumbled across this great article over at DeviantPoint. It was pretty much exactly what I needed. However, for my example I needed to only show the dialog box if any of the checkboxes on the screen were not selected. In other words a normal postback would occur if every check was selected but if there were any checkboxes not selected the user would be asked to confirm their action.

    If you take a look at my very basic demo page you will see exactly what I'm talking about. You will find all of the code within the source files I have posted for download but below is a brief overview of what is going on.

    View Demo | Download Source

    HTML used:

    This is a top class widget. Features include...

    Below are the required items for this product to function correctly:
    Required Item 1 Required Item 2
    Required Item 3 Required Item 4

    Javascript used:

    // 
    

    $(document).ready(function() {

    $(function () {

    $("#MsgBox").dialog({

    autoOpen: false,

    modal: true,

    buttons: {

    "Continue": function () {

    $(this).dialog("close");

    eval($("#<%= MsgBoxContinue.ClientID %>").val());

    },

    "Cancel": function () {

    $(this).dialog("close");

    }

    }

    });

    });

    });

    function showjQueryDialog() {

    //check to see how many checkboxes there are and how many of those are checked.

    //if any of the checkboxes are not selected then show dialog box.

    var TotalNumCheckboxes = $("#ContentContainer input:checkbox").length;

    var TotalNumCheckboxesChecked = $("#ContentContainer input:checkbox:checked").length;

    if (TotalNumCheckboxes == TotalNumCheckboxesChecked)

    {

    eval($("#<%= MsgBoxContinue.ClientID %>").val());

    }

    else

    {

    $("#MsgBox").dialog("open");

    }

    }

    // ]]>

    C# Codebehind:

    if (!Page.IsPostBack)

    {

    //this line is used to hold the exact postback function call used by the asp.net button

    this.MsgBoxContinue.Value = Page.ClientScript.GetPostBackEventReference(AddToBasket, string.Empty);

    //ensure the postback message is blank on load

    PostBackMsgTest.Text = "";

    }

    if (Page.IsPostBack)

    {

    PostBackMsgTest.Text = "Content posted back successfully.";

    }

  • Hide a Repeater and it's header text when there are no items to display using C#

    One of the annoying little things about the asp.net repeater is that if you have text in a <HeaderTemplate> this will be shown on screen even if the repeater is empty. Nine times out of ten you will actually want to hide the text and only show it if the repeater contains information. This can be done by doing the following:

    First adjust your repeater so that on PreRender of the repeater you call some code from your code behind:

    Header text inside my repeater

    ... show database values in here ...

    Next on your code behind page put in the following to check if the repeater contains any values:

    protected void MyRepeater_PreRender(object sender, System.EventArgs e)

    {

    //check to see if the repeater contains any items and if not hide it

    if (MyRepeater.Items.Count == 0)

    {

    MyRepeater.Visible = false;

    }

    }

    Fire up your page and test the repeater with and without items inside it. You should notice that when the repeater is empty the header text is not displayed which is what we wanted to happen.

  • How to check if your drop down list contains a specific value using C#

    If you want to set the default value of a drop down list from a value being passed to you by a third party you should always include a check to ensure that your drop down contains the value so that you don't end up with some nasty compiler errors.

    To keep things simple let's say I want to check if my drop down contains the value "MyValue". If it does I want to pre-select that option for the user. To do this I would use something like below:

    if (MyDropDownList.Items.FindByValue("MyValue") != null)

    {

    MyDropDownList.SelectedValue = "MyValue";

    }

    You can also search based on the text value of your drop down by using FindByText instead of FindByValue.

  • Hertz and Aerlingus team up for new project HertzFlyDrive.com, designed and developed by Dragnet Systems

    HertzFlyDrive.com - A new car rental site from Hertz and Aerlingus, designed and developed by Dragnet Systems

    After many months of work I'm proud to announce my latest project HertzFlyDrive.com. This website was designed from the ground up provide Hertz with a more effective way to manage their car rental booking information and help speed up the booking process for end users.

  • how to sort a DataTable by a specific column using C#

    The majority of the time when displaying content to the end user you will want to order the data by certain criteria. More often than not you will want to sort by a specific column. If your data is in a DataTable how do you do that?

    You need to convert your DataTable into a DataView, apply your sort and save the results back to your DataTable. Let's say we have a DataTable that holds details of all our customers and we want to order the information by their names. To keep things simple I will hard code in only 2 customer values here. You would order the information by doing the following:

    using System.Data;

    //create our datatable and setup with 2 columns

    DataTable dt = new DataTable();

    dt.Columns.Add("CustomerFirstname", typeof(string));

    dt.Columns.Add("CustomerSurname", typeof(string));

    DataRow dr;

    //store some values into datatable

    //just using 2 names as example

    dr = dt.NewRow();

    dr["CustomerFirstname"] = "John";

    dr["CustomerSurname"] = "Murphy";

    dt.Rows.Add(dr);

    dr = dt.NewRow();

    dr["CustomerFirstname"] = "John";

    dr["CustomerSurname"] = "Doe";

    dt.Rows.Add(dr);

    //check to make sure our datatable has at

    //least one value. For this example it's not

    //really need but if we were taking the

    //values from a database then this would be

    //very important!

    if (dt.Rows.Count > 0)

    {

    //convert DataTable to DataView

    DataView dv = dt.DefaultView;

    //apply the sort on CustomerSurname column

    dv.Sort = "CustomerSurname";

    //save our newly ordered results back into our datatable

    dt = dv.ToTable();

    }

    //display your datatable to the user by databinding

    //to repeater/gridview

  • How to get the values of HTML checkboxes within a Repeater using C#

    If you want to read in a bunch of HTML checkboxes that are in a repeater using C# then you need to add a runat="server" element to you checkbox input tag. For example:

    In your code behind you can now read in this element by using the following code:

    using System.Web.UI.HtmlControls;

    foreach (RepeaterItem currentControl in MyRepaterList.Items)

    {

    HtmlInputCheckBox MyCheckBox = new HtmlInputCheckBox();

    MyCheckBox = (HtmlInputCheckBox)currentControl.FindControl("CheckboxName");

    if (MyCheckBox.Checked)

    {

    //logic if checkbox is ticked here

    }

    }

    The above code will loop through all the HTML checkbox elements within your repeater. You can easily modify this to let you look for HTML textboxes (HtmlInputText), HTML radio buttons (HtmlInputRadioButton), etc.

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