C #. net under the simple Ajax example -- Ajax. dll http://www.diybl.com/network CLICK: 1741 [comment]
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I have studied how to use Ajax. dll to implement the previous example. It is very frustrating because it is simpler, less code, and only a bit of it. Therefore, if Ajax is required for a project, we suggest you study the framework, such as Ext. Its Class Libraries and documents are quite rich and easy to use.
Okay, I will list the implementation process. First, we need an Ajax. dll file. Find it by yourself! Put it in the project and add references. First, you need a class named "AjaxMethod. cs" as follows:
Namespace Test. AjaxTest
{
/// <Summary>
/// Summary of AjaxMethod.
/// </Summary>
Public class AjaxMethod
{
Public AjaxMethod (){}
// Database query operation
[Ajax. AjaxMethod (Ajax. HttpSessionStateRequirement. Read)]
Public DataSet GetList (string id)
{
String SQL = "select CityName, CityCode from City where [ID] =" + id;
Return SelectData (SQL); // call the following method
}
//
Private DataSet SelectData (string SQL)
{
// Database link definition:
// <Configuration> <etettings> </appSettings> </configuration> in Web. config
// Add definition: <add key = "ConnectionString" value = "data source = localhost;
// Initial catalog = helpalog 1; user id = sa; password = sa; "> </add>
String cs = System. Configuration. ConfigurationSettings
. Etettings ["ConnectionString"];
// Or define it like this.
// String cs = "Server = (local); UID = sa; PWD = sa; Database = help1_1 ";
SqlDataAdapter sda = new SqlDataAdapter (SQL, cs );
DataSet ds = new DataSet ();
Sda. Fill (ds );
Return ds;
}
}
}
Article Source: http://www.diybl.com/course/4_webprogram/asp.net/asp_netshl/2007125/90636.html
The following figure shows the page a. aspx to achieve the effect. The <body> part is simple:
<Body>
<Form id = "Form1" method = "post" runat = "server">
<Select id = "AList" onchange = "GetBList ()">
<Option value = "0"> A </option>
<Option value = "1"> B </option>
<Option value = "2"> C </option>
</Select>
<Select id = "BList"> </select>
</Form>
</Body> when the onchange event is triggered on the page, the GetBList () method is entered. The following shows the complete JavaScript code for the page:
<Script language = "javascript">
Function GetBList (){
// Call the Database Operation Method
Var av = document. getElementById ("AList"). value;
// Call the method of the AjaxMethod class. Here there are two parameters. I guess it is a delegate,
// Pass the GetList execution result DataSet to the SetBList method, hiding
AjaxMethod. GetList (av, SetBList );
}
Function SetBList (response ){
If (response! = Null ){
Var ds = response. value; // return set
// This is quite special. At first, I felt something went wrong. Why is the js syntax the same as c #?
// The Regular Expression in Ajax. dll should be strong! However, this is a bit unpleasant.
// During the test, ds. Tables [0]. Rows. lenght is written as ds. Tables [0]. Rows. Count
// Js will not find the object error.
// We still need to get used to its rules. After all, it is not entirely c #, but it just defines a rule similar to c #
// Very similar syntax rules
If (ds! = Null & typeof (ds) = "object" & ds. Tables! = Null ){
Alert (ds. Tables [0]. Rows. length );
For (var I = 0; I <ds. Tables [0]. Rows. length; I ++ ){
Var option = document. createElement ("OPTION ");
Option. value = ds. Tables [0]. Rows [I]. CityCode;
Option. text = ds. Tables [0]. Rows [I]. CityName;
Document. Form1.BList. options. add (option );
}
}
}
}
</Script> This example ends, and many complex operations are encapsulated. What we learned is how to use it. That's all. However, when we catch up with the project, it can bring a lot of convenience.
Article Source: http://www.diybl.com/course/4_webprogram/asp.net/asp_netshl/2007125/90636_2.html
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