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Moving forward, we will create a jQuery
collapsible panel that can load the data only when it is required. We will use
the same collapsible panel implementation we used in my previous article. We
will populate the panels with articles list in different categories.
Steps
1. Open Visual Studio 2008 from the Start menu. Click File > New > Website and select ASP.Net
Website from "Visual Studio Installed templates".
2. Choose a language of your choice(I have selected C#) and name
the website as per the need.
3. Download the latest jQuery library from jQuery.com and integrate into
your project. Read the following Faq’s to integrate jQuery library to your
project.
What
is jQuery? How to use it in ASP.Net Pages?
How
to enable jQuery intellisense in Visual Studio 2008?
How
to use jQuery intellisense in an external javascript file?
4. Next, we will define our collapsible panels in our asp.net page. For
simplicity purpose, i will define 3 panels to load articles in 3 different
categories.
<div id="ContainerPanel"
class="ContainerPanel">
<div id="header"
class="collapsePanelHeader">
<div id="dvHeaderText"
class="HeaderContent">ASP.Net Articles</div>
<div id="dvArrow"
class="ArrowExpand" title="ASP.Net"></div>
</div>
<div id="dvASPNET"
class="Content" style="display:none">
</div>
</div>
<br />
<div id="Div1"
class="ContainerPanel">
<div id="Div2"
class="collapsePanelHeader">
<div id="Div3"
class="HeaderContent">Csharp Articles</div>
<div id="Div4"
class="ArrowExpand" title="Csharp"></div>
</div>
<div id="dvCSharp"
class="Content" style="display:none">
</div>
</div>
<br />
<div id="Div6"
class="ContainerPanel">
<div id="Div7"
class="collapsePanelHeader">
<div id="Div8"
class="HeaderContent">jQuery Articles</div>
<div id="Div9"
class="ArrowExpand" title="jQuery"></div>
</div>
<div id="dvjQuery"
class="Content" style="display:none">
</div>
</div>
Script
$(document).ready(function() {
$("DIV.ContainerPanel >
DIV.collapsePanelHeader > DIV.ArrowExpand").toggle(
function() {
$(this).parent().next("div.Content").show("slow");
$(this).attr("class",
"ArrowClose");
},
function() {
$(this).parent().next("div.Content").hide("slow");
$(this).attr("class",
"ArrowExpand");
});
});
To identify the article category to
populate for a particular panel, we will add a title property [bolded text in
the above code] to the div tag that holds in expand/collapse button. When the
user clicks the expand button, we will call an ashx handler which can accept an
article category [obtained from the title property of the div] and return a json
string of article list on that category.
5. Now, we will add an ashx hander that can get article category as a
query string and return list of articles on that category in json format. To do
this, Right click the project in solution and click “Add New Item”. Select
“Generic Handler”. I have named as GetArticles.ashx. Refer the below
code,
public class GetArticles : IHttpHandler
{
public void ProcessRequest
(HttpContext context) {
string Category =
context.Request.QueryString["Cat"];
//Pass the article category as
paramter to the query
string query = "SELECT * FROM
[Articles]";
DataTable dt =
GetDt(query);
StringBuilder strArticles = new
StringBuilder();
if (dt != null)
{
strArticles.Append("{
Articles:[");
for (int i = 0; i <
dt.Rows.Count; i++)
{
strArticles.Append("{");
strArticles.Append("\"ArticleID\":\"" + dt.Rows[i]["ArticleID"].ToString() +
"\",");
strArticles.Append("\"Title\":\"" + dt.Rows[i]["Title"].ToString() +
"\",");
strArticles.Append("\"Category\":\"" + dt.Rows[i]["Category"].ToString() +
"\",");
strArticles.Append("\"Author\":\"" + dt.Rows[i]["Author"].ToString() +
"\",");
strArticles.Append("\"URL\":\"" + dt.Rows[i]["URL"].ToString() +
"\"");
if (i != dt.Rows.Count -
1)
{
strArticles.Append("},");
}
}
}
strArticles.Append("}");
strArticles.Append("]}");
context.Response.ContentType =
"application/json";
context.Response.ContentEncoding =
Encoding.UTF8;
context.Response.Write(strArticles.ToString());
context.Response.End();
}
public bool IsReusable {
get {
return false;
}
}
public DataTable GetDt(string
query)
{
SqlConnection con = new
SqlConnection(ConfigurationManager.ConnectionStrings["Sql"].ConnectionString);
SqlDataAdapter ada = new
SqlDataAdapter(query, con);
DataTable dt = new
DataTable();
ada.Fill(dt);
return dt;
}
}
In the above code, i am returning the
articles on all categories without doing filtration. You can rewrite the query
to filter based on the querystring value. The above handler will fetch the data
from the SQL express database in App_Data folder. I have created the JSON format
manually. If you have ASP.Net AJAX installed on the server you can try using
JavaScriptSerializer class packed in System.Web.Script.Serialization namespace
to convert objects to JSON format. You can also try using
DataContractJsonSerializer class for creating json strings.
6. Next, we will call the ashx handler when the user clicks expand
button and pass the title as a querystring to the handler to get json list of
articles. We will populate the panel with the list of article in tabular format
using returned json string. To make it simple, we will use jTemplate plugin to
format the json into a tabular format and populate it in the panel.
You can visit the jTemplate site here to know more aboute jTemplate plugin.
Integrating jTemplate plug-in in
your Project
1. Grab the newer version of jTemplate plug-in either from jTemplate site or jQuery site.
2. Copy the plug-in to your solution and link it through script
tag.
<script
src="_scripts/jquery-jtemplates.js"
type="text/javascript"></script>
First, we will build our tabular
template that is required to populate the json string. Include an htm file into
the solution and name it as temp.htm. Refer the below code for the
template,
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