如果未从下拉菜单中选择用户,如何显示回显

时间:2012-10-27 21:02:00

标签: php

在下面的代码中,我有2个下拉菜单。一个是“课程”下拉菜单,另一个是“模块”下拉菜单:

以下是代码:

   <?php

    // connect to the database
    include('connect.php');

    /* check connection */
    if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    die();
    }

    $sql = "SELECT CourseId, CourseName FROM Course ORDER BY CourseId"; 

    $sqlstmt=$mysqli->prepare($sql);

    $sqlstmt->execute(); 

    $sqlstmt->bind_result($dbCourseId, $dbCourseName);

    $courses = array(); // easier if you don't use generic names for data 

    $courseHTML = "";  
    $courseHTML .= '<select name="courses" id="coursesDrop" onchange="getModules();">'.PHP_EOL; 
    $courseHTML .= '<option value="">Please Select</option>'.PHP_EOL;  

    while($sqlstmt->fetch()) 
    { 
    $course = $dbCourseId;
    $coursename = $dbCourseName; 
    $courseHTML .= "<option value='".$course."'>" . $course . " - " . $coursename . "</option>".PHP_EOL;  
    } 

    $courseHTML .= '</select>'; 

    $moduleHTML = "";  
    $moduleHTML .= '<select name="modules" id="modulesDrop">'.PHP_EOL; 
    $moduleHTML .= '<option value="">Please Select</option>'.PHP_EOL;  
    $moduleHTML .= '</select>'; 


    include('noscript.php');

    ?>

    <script type="text/javascript">

    function getModules() { 
    var course = jQuery("#coursesDrop").val(); 
    jQuery('#modulesDrop').empty(); 
    jQuery('#modulesDrop').html('<option value="">Please Select</option>'); 
    jQuery.ajax({ 
    type: "post", 
    url:  "module.php", 
    data: { course:course }, 
    success: function(response){ 
    jQuery('#modulesDrop').append(response); 
    } 
    }); 


    }

    </script> 

<h1>EDIT AN ASSESSMENT'S DATE/START TIME</h1>    

<form action="<?php echo htmlentities($_SERVER['PHP_SELF']); ?>" method="post">
<table>
<tr>
<th>Course: <?php echo $courseHTML; ?></th>
<th>Module: <?php echo $moduleHTML; ?></th>
</tr>
</table>
<p><input id="moduleSubmit" type="submit" value="Submit" name="moduleSubmit" /></p>
</form>

<?php

if (isset($_POST['moduleSubmit'])) {

$sessionquery = "
SELECT SessionId, SessionDate, SessionTime, ModuleId, TeacherId
FROM Session
WHERE
(ModuleId = ? AND TeacherId = ?)
ORDER BY SessionDate, SessionTime 
";

$sessionqrystmt=$mysqli->prepare($sessionquery);
// You only need to call bind_param once
$sessionqrystmt->bind_param("si",$moduleId,$userid);
// get result and assign variables (prefix with db)

$sessionqrystmt->execute(); 

$sessionqrystmt->bind_result($dbSessionId,$dbSessionDate,$dbSessionTime, $dbModuleId, $dbTeacherId);

$sessionqrystmt->store_result();

$sessionnum = $sessionqrystmt->num_rows();   

if($sessionnum ==0){
echo "<p>Sorry, You have No Sessions under this Module</p>";

module.php,显示“Module”下拉菜单:

 <?php

         // connect to the database
     include('connect.php');

     /* check connection */
     if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    die();
    }


    $course = isset($_POST['course']) ? $_POST['course'] : ''; 

    $sql = "
    SELECT cm.CourseId, cm.ModuleId, 
    c.CourseName,
    m.ModuleName
    FROM Course c
    INNER JOIN Course_Module cm ON c.CourseId = cm.CourseId
    JOIN Module m ON cm.ModuleId = m.ModuleId
    WHERE
    (c.CourseId = ?)
    ORDER BY c.CourseId, m.ModuleId
    "; 

     $sqlstmt=$mysqli->prepare($sql);

     $sqlstmt->bind_param("s",$course);

     $sqlstmt->execute(); 

     $sqlstmt->bind_result($dbCourseId,$dbModuleId,$dbCourseName,$dbModuleName);


    $moduleHTML  = "";  

     while($sqlstmt->fetch()) { 
        $moduleHTML .= "<option value='$dbModuleId'>" . $dbModuleId . " - " . $dbModuleName . "</option>".PHP_EOL;   
    } 


    echo $moduleHTML; 

     $sqlstmt->execute(); 


    ?>

现在,如果你查看代码的底部,会发生的是它在用户提交“课程”和“模块”下拉菜单后执行查询。如果它没有找到与该模块相关的会话,那么它会回显"Sorry, You have No Sessions under this Module"

但我的问题是,如果用户没有从下拉菜单中选择“课程”和“模块”,或者用户从“课程”中选择了课程,我不希望显示此回显下拉菜单但未从“模块”下拉菜单中选择模块。

以下是我想要的每种情况的回声:

  1. 如果用户未选择课程和模块:echo "Please Select a Course and Module";
  2. 如果用户选择了课程但未选择模块:echo "Please Select a Module";
  3. 如果用户选择了课程和模块但没有会话显示:echo "Sorry, You have No Sessions under this Module";
  4. 目前上面的列表3可以工作,但是如何通过仅显示回显而没有其他回声来使列表1和2工作?

    更新

    验证下拉菜单的Javascript代码:

         function validation() {
    
                    var isDataValid = true;
    
                    var moduleTextO = document.getElementById("coursesDrop");
                var courseTextO = document.getElementById("modulesDrop");
    
                var errModuleMsgO = document.getElementById("moduleAlert");
    
      if (courseTextO.value == "" && moduleTextO.value == ""){
              errModuleMsgO.innerHTML = "Please Select a Course and Module";
              isDataValid = false;
      } else if (courseTextO.value == ""){
              errModuleMsgO.innerHTML = "Please Select a Course";
              isDataValid = false;      
      }else  if (moduleTextO.value == ""){
              errModuleMsgO.innerHTML = "Please Select a Module";
              isDataValid = false;    
        }else{
                    errModuleMsgO.innerHTML = ""; 
            }
    
            return isDataValid;
    
            }
    

    以下是HTML代码:

    <form action="<?php echo htmlentities($_SERVER['PHP_SELF']); ?>" method="post">
    <table>
    <tr>
    <th>Course: <?php echo $courseHTML; ?></th>
    <th>Module: <?php echo $moduleHTML; ?></th>
    </tr>
    </table>
    <p><input id="moduleSubmit" type="submit" value="Submit" name="moduleSubmit" /></p>
    <div id="moduleAlert"></div>
    </form>
    

2 个答案:

答案 0 :(得分:1)

你可以使用javascript在其中创建一个函数,在那里你可以检查天气每个字段是否填充可以在这里显示

<script type="text/javascript">
function validate()
{
if(document.dropdownmenuname.course.value=="")
{
alert("Please fill in your form");
document.dropdownmenuname.course.focus() ;
 return false;
}
}
....

答案 1 :(得分:0)

更改表单标记

<form action="<?php echo htmlentities($_SERVER['PHP_SELF']); ?>" method="post">

<form action="<?php echo htmlentities($_SERVER['PHP_SELF']); ?>" method="post" onsubmit="return validation();">

在服务器端进行验证也是一个好主意,如果要在服务器端检查值,只需在现有PHP中添加一些代码:

<?php

if (isset($_POST['moduleSubmit'])) {

if(empty($_POST['courses']) && empty($_POST['modules'])) {
   echo 'Please Select a Course and Module';
} elseif(empty($_POST['courses'])) {
   echo 'Please Select a Course';
} elseif(empty($_POST['modules'])) {
   echo 'Please Select a module';
} else {

$sessionquery = "
SELECT SessionId, SessionDate, SessionTime, ModuleId, TeacherId
FROM Session
WHERE
(ModuleId = ? AND TeacherId = ?)
ORDER BY SessionDate, SessionTime 
";

$sessionqrystmt=$mysqli->prepare($sessionquery);
// You only need to call bind_param once
$sessionqrystmt->bind_param("si",$moduleId,$userid);
// get result and assign variables (prefix with db)

$sessionqrystmt->execute(); 

$sessionqrystmt->bind_result($dbSessionId,$dbSessionDate,$dbSessionTime, $dbModuleId, $dbTeacherId);

$sessionqrystmt->store_result();

$sessionnum = $sessionqrystmt->num_rows();   

if($sessionnum ==0){
echo "<p>Sorry, You have No Sessions under this Module</p>";

}