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我創建了一個Ajax函數，專門用於讀取來自FORM的輸入，創建一個查詢字符串並將其發送到PHP文件，該文件將數據插入數據庫併發送指示成功或失敗的反饋的過程。Ajax XMLHttpRequest.responseText有條件工作
問題是Ajax XMLHttpRequest.responseText不起作用。 這意味着，最終用戶不會從php文件獲得反饋：如果過程成功或失敗。
奇怪的是，我發現當我在Ajax函數的末尾放置alert（）函數時，XMLHttpRequest.responseText神奇地開始工作。正如你可以想象的那樣，每次進程運行時都會彈出一個彈出窗口，這很煩人。
有人可以幫我理解爲什麼會發生這種情況。
// FORM
class Teacher {
function AddATeacher()
{
## Template for form with image ##
echo "<img src='../images/addaTeacher.png' alt='add A teacher icon' align='middle' width='90' height='90' />";
echo " <b>                    Add a Teacher </b> <br> <br>";
## Template for form with image ##
echo "<form name ='login' onsubmit='AddATeachers()' method='post'>";
echo "First Name: &emsp&emsp&emsp&emsp&emsp <input type='text' size='15' maxlength='15'
onclick=this.value='' id='teachers_first_name'
value='Teachers First Name' /> <br>";
echo "Surname: &emsp&emsp&emsp&emsp&emsp&emsp<input type='text' size='15' maxlength='15'
onclick=this.value='' id='teachers_surname'
value='Teachers surname' /> <br>";
echo "Number: &emsp&emsp&emsp&emsp&emsp &emsp <input type='text' size='15' maxlength='15'
onclick=this.value='' id='teachers_number'
value='Teachers number' /> <br>";
echo "Email address: &emsp&emsp&emsp&emsp<input type='text' size='15'
maxlength='25' onclick=this.value='' id='teachers_email'
value='Email address' /> <br>";
echo "Password: &emsp &emsp &emsp&emsp&emsp <input type='password' size='15'maxlength='25'
id='password' value='' /> <br>";
echo "<hr/>";
echo "
Sex:
<select value= 'Male' id='sex'>
<option> </option>
<option>Male</option>
<option>Female</option>
</select> ";
echo "
Assigned Class:
<select value= 'Choose a class' id='classes'>
<option> </option>
<option>P1 East</option>
<option>P1 West</option>
<option>P2 East</option>
<option>P2 West</option>
<option>p3 East</option>
<option>p3 West</option>
<option>p4 East</option>
<option>p4 West</option>
<option>p5 East</option>
<option>p5 West</option>
<option>p6 East</option>
<option>p6 West</option>
<option>p7 East</option>
<option>p7 West</option>
</select>";
echo"
<hr/>
<input type='submit' value='Submit' /><br />";
echo "</form>";
}
}
// AJAX FUNCTION
function AddATeachers(){
var ajaxRequest; // The variable that makes Ajax possible!
try{
// Opera 8.0+, Firefox, Safari
ajaxRequest = new XMLHttpRequest();
} catch (e){
// Internet Explorer Browsers
try{
ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try{
ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e){
// Something went wrong
alert("Your browser broke!");
return false;
}
}
}
// Create a function that will receive data sent from the server
ajaxRequest.onreadystatechange = function(){
if(ajaxRequest.readyState == 4){
document.getElementById("Ajax_response").innerHTML = ajaxRequest.responseText;
}
}
//alert ("Above ur variables ");
var teachers_first_name = document.getElementById("teachers_first_name").value;
//alert ("within ur variables 1111111111 ");
var teachers_surname = document.getElementById('teachers_surname').value;
var teachers_number = document.getElementById('teachers_number').value;
//alert ("within ur variables 222222222 ");
var teachers_email = document.getElementById('teachers_email').value;
var password = document.getElementById('password').value;
//alert ("Email retrieved: " + password + "");
var tClass = document.getElementById('classes').value;
var gender = document.getElementById('sex').value;
//alert ("Class value: " + tClass + "");
//alert ("Exited ur variables ");
//alert ("Just before Query String...");
var queryString = "?tFirstName=" + teachers_first_name + "&tSurname=" + teachers_surname + "&tNumber=" + teachers_number + "&tEmail=" + teachers_email + "&tPwd=" + password + "&tSex=" + gender + "&tClass=" + tClass ;
//alert ("After Query String...");
ajaxRequest.open("GET","addATeacherInsert.php" + queryString, true);
ajaxRequest.send(null);
alert ("Process Complete");
}
// addATeacherInsert.php它調用一個類的方法/實例
<?php
require ("database.php");
require ("teacher.class");
mysql_connect(HOSTNAME, USERNAME, PASSWORD) or die(mysql_error());
//echo "Connected to MySQL<br /> <br />";
mysql_select_db(DATABASE) or die(mysql_error());
//echo "Connected to Database: " . DATABASE . " <br />";
$sql = ("SELECT * FROM Teachers_Table WHERE TFirstName='$_GET[tFirstName]' AND TSurName= '$_GET[tSurname]' ");
$query = mysql_query($sql);
$Sample = new Teacher;
$Sample->AddATeacherInsert();
?>
// METHOD
function AddATeacherInsert()
{
mysql_connect(HOSTNAME, USERNAME, PASSWORD) or die(mysql_error());
//echo "Connected to MySQL<br /> <br />";
mysql_select_db(DATABASE) or die(mysql_error());
//echo "Connected to Database: " . DATABASE . " <br />";
##### Insert into Teachers_Table ######
mysql_query("INSERT INTO Teachers_Table
(TFirstName, TSurName, TNumber, TAddress, TPwd, TClassAssig, TSex) VALUES
('$_GET[tFirstName]', '$_GET[tSurname]', '$_GET[tNumber]', '$_GET[tEmail]',
'$_GET[tPwd]', '$_GET[tClass]', '$_GET[tSex]') ")
or die(mysql_error());
##### Insert into login_details ######
mysql_query("INSERT INTO login_details
(email_address, password) VALUES
('$_GET[tEmail]', '$_GET[tPwd]') ")
or die(mysql_error());
echo "<br>";
echo "<center> <img src='../images/approved.png' alt='Enroll student icon' align='bottom' width='90' height='90' /> </center>";
echo "<br><center> <b> <font color='blue'>" . $_GET[tFirstName] . " " . $_GET[tSurname] . "</b> has been successfully enrolled...</font></center><br />";
}
預先感謝您