在ASP.NET中實現AJAX（三）

處理類型

 

返回複雜類型

Ajax封裝器不僅能處理ServerSideAdd函數所返回的整數。它目前還支援integers、strings、double、booleans、DateTime、DataSets和DataTables，以及自訂類和數組等基本類型。其他所有類型都返回它們的ToString值。

返回的DataSets和真正的.NET DataSet差不多。假設一個伺服器端函數返回DataSet，我們可以通過下面的代碼在用戶端顯示其中的內容:

<script language="JavaScript">

//Asynchronous call to the mythical "GetDataSet" server-side function

function getDataSet(){

AjaxFunctions.GetDataSet(GetDataSet_callback);   

}

function GetDataSet_callback(response){

var ds = response.value;

if(ds != null && typeof(ds) == "object" && ds.Tables != null){

var s = new Array();

s[s.length] = "<table border=1>";

for(var i=0; i<ds.Tables[0].Rows.length; i++){

s[s.length] = "<tr>";

s[s.length] = "<td>" + ds.Tables[0].Rows[i].FirstName + "</td>";

s[s.length] = "<td>" + ds.Tables[0].Rows[i].Birthday + "</td>";

s[s.length] = "</tr>";

}

s[s.length] = "</table>";

tableDisplay.innerHTML = s.join("");

}

else {

alert("Error. [3001] " + response.request.responseText);

}

}

</script>

Ajax還可以返回自訂類，唯一的要求是必須用Serializable屬性標記。假設有如下的類:

[Serializable()]

public class User{

private int _userId;

private string _firstName;

private string _lastName;

  public int userId{

get { return _userId; }

}

public string FirstName{

get { return _firstName; }

}

public string LastName{

get { return _lastName; }

}

public User(int _userId, string _firstName, string _lastName){

this._userId = _userId;

this._firstName = _firstName;

this._lastName = _lastName;

}

public User(){}

[AjaxMethod()]

public static User GetUser(int userId){

//Replace this with a DB hit or something

return new User(userId,"Michael", "Schwarz");

}

}

我們可以通過調用RegisterTypeForAjax註冊GetUser代理:

private void Page_Load(object sender, EventArgs e){

Utility.RegisterTypeForAjax(typeof(User));

}

這樣就可以在用戶端非同步呼叫GetUser:

<script language="javascript">

function getUser(userId){

User.GetUser(GetUser_callback);

}

function GetUser_callback(response){

if (response != null && response.value != null){

var user = response.value;

if (typeof(user) == "object"){         

alert(user.FirstName + " " + user.LastName);

}

}

}

getUser(1);

</script>

響應中返回的值實際上是一個對象，公開了和伺服器端對象相同的屬性(FirstName、LastName和UserId)。

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