Tuesday, February 19, 2013

Add clickable rows in csharp DataTable and bind to asp.net gridview

Responding to a good demand from a lot of readers, I have now presented a way to create DataTable programmatically where rows accept html and hence they can be made clickable. Complementing to my previous post on creating DataTable programmatically in asp.net, this tips will bind DataTable to an asp.net GridView where one of the columns in each row contains clickable html anchor.

Below is the code snippet in C#.

protected void Page_Load(object sender, EventArgs e)
        if (!IsPostBack)
            //get data from programmatically created DataTable and bind to GridView
            gvTable.DataSource = CreateTable();

//Create DataTable programmatically
    //In this example, there are three columns
    //namely ID, WebsiteName and URL
    private DataTable CreateTable()
        //create datatable
        DataTable table = new DataTable("Websites");
        //add columns to the table
        table.Columns.Add("ID", typeof(int));
        table.Columns.Add("WebsiteName", typeof(string));
        table.Columns.Add("URL", typeof(string));
        //add as many rows as you want
        AddNewRow(1, "dotnetspidor", "http://dotnetspidor.blogspot.com", table);
        AddNewRow(1, "asp.net", "http://asp.net", table);
        AddNewRow(1, "codeplex", "http://codeplex.com", table);
        return table;

//Add new row to a table
    private void AddNewRow(int id,string website, string url,DataTable table)
        DataRow row = table.NewRow();
        row["ID"] = id;
        row["WebsiteName"] = website;
        //get url from GetURL method
        string link = GetURL(website, url);
        row["URL"] = HttpUtility.HtmlDecode(link);

//create html anchor from website name and it's url
    private string GetURL(string website, string url)
        return "<a href=\""+url+"\">"+website+"</a>";

Here goes the design code for the GridView. Please note the property HtmlEncode="false" in the third BoundField. This prevents the GridView from rendering encoded html so we retain the html code from our DataTable column.

    <asp:gridview autogeneratecolumns="false" id="gvTable" runat="server" width="500px">  
<asp:boundfield datafield="ID" headertext="ID">
<asp:boundfield datafield="WebsiteName" headertext="Website">
<asp:boundfield datafield="URL" headertext="URL" htmlencode="false">

The output looks like below.
Fig: Output of programmatically generated DataTable in a gridview - with clickable row
Happy Programming!!
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Saturday, February 9, 2013

Strip html tags and extract subset of string from text using regular expression in c-sharp

Today I am presenting a quick tips on how to strip html from text using regular expression (with Regex class) in C#. In a scenario like presenting a blurb or summary of certain characters we may need to remove html tags from a html string (of news details, article details etc.). I have following function in my Helper library for the very problem.

    /// Strip out html tags from text
    /// Source string
    public static string StripTagsFromHtml(string source)
        return Regex.Replace(source, "<.*?>", string.Empty);

To extract a number of characters from the source string, we can extend the function as following.

    /// Strip out html tags from text and return extract from it
    /// Source string
    /// Number of characters to extract
    public static string StripTagsFromHtml(string source, int characterCount)
        string stripped = Regex.Replace(source, "<.*?>", string.Empty);
        if (stripped.Length <= characterCount)
            return stripped;
            return stripped.Substring(0, characterCount);

Happy programming!

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