相关下拉列表无法正常工作

Question

在下面的代码中在更新部分：有2个文本框和2个下拉列表。一个下拉列表是课程代码，另一个是主题代码，当我通过选择相应的课程代码更新主题代码时相应的不显示它显示主题代码下拉列表中的空白屏幕。请任何人帮助我。

     View:Student_detail_view


<section id="tables">
<script>
 jQuery(document).ready(function() {
  oTable = jQuery('#studenttable').dataTable({
   "bJQueryUI": true,
   "sPaginationType": "full_numbers"

  });
   }); 
  </script> 
  <script type="text/javascript" charset="utf-8">
 function get_studentdetails() {

    var exam_name = jQuery('#exam_name_id').val();
    //alert("exam_name"+exam_name);
    jQuery.ajax({
        data: {
            exam_name: exam_name,
        },
        type: 'POST',
        url: 'student_site/studentupdate',          
        success: function(data){
        //alert("inside change");
            console.log(data);
            jQuery('#details').html(data);
            jquery('#deleting').html(data);
        }
    });
    jQuery(document).ready(function(){
    jQuery.ajax({
        data: {
            exam_name: exam_name,
        },
        type: 'POST',
        url: 'student_site/studentcreate',
        success: function(data){
        //alert("inside change");
            console.log(data);
            jQuery('#crud').html(data);
            jquery('#deleting').html(data);
        }
    }); 
    });
}     

function CheckBoxVerification(From)
{
alert('hai');
    alert('hai:' $("table input[type=checkbox]:checked").length);
    if(From == "Insert")
    {
        if(!!$('#rowInsert input:checked').length == false)
        {
            alert('please select at least one check box to Create ...!');
        }
    }

    if(From == "Update")
    {
        if(!!$('#rowUpdate input:checked').length == false)
        {
            alert('please select at least one check box to Update ...!');
        }
    }
}
  function get_subjectdetails1() {
    //var index = jQuery('#index').val();

    var course_name = jQuery('#course_name_id').val();
    //alert("course_name"+course_name);
    var exam_name = jQuery('#course_name_id>option:selected').text();
    var exam_name = jQuery('#exam_name_id').val();
    var ssubject_code = jQuery('#ssubject_code_id').val();
    //var partsArray = exam_name.split('.');
    //alert("ssubject_code"+ssubject_code);
    //alert("course_name"+course_name);
    //alert("exam_name"+exam_name);
    jQuery.ajax({
        data: 'exam_name='+exam_name+'&course_name=' + course_name,
        type: 'POST',
        url: 'student_site/subject_records',
        success: function(data){
        //alert("inside change");
            console.log(data);
            //alert ("data"+data);
            //for(var j = course_name; j < ssubject_code; j++)
        //{
            jQuery('#ssubject_code').empty().append(data);
        //}
        }

    });
} 

</script>

<?php 
    $attributes=array(
        'name'=>'updatecustomer',
        'id'=>'updatecustomer'
        );
    echo form_open('student_site/manage_student',$attributes);
?>
<div id="validation_failed">
    <?php
        echo validation_errors();
    ?>
    <?php $data = array();
        foreach ($course_records as $row)
        {
            $data[$row->course_code] = $row->course_code; 
        } 

        $subject_data = array();
        foreach ($all_coursesubject_records as $row)
        {
            $subject_data[$row->subject_code] = $row->subject_code; 
        }  


     ?>
     <div id="Processy">
<table class="display table table-bordered table-striped" id='studenttable'>
<thead>
<tr font style='font-size:13px'>
<th>&nbsp;</th>
<th>&nbsp;</th>
<th>Register Number</th>
<th>Name </th>
<th>Course Code</th>
<th>Subject Code</th>
</tr></thead>
<?php if(isset($records)) : foreach($records as $row) : ?>
<tr >
<td>
<?php echo anchor('student_site/delete/'.$row->id, 'Delete',array('onClick'=>"return confirm('Are you sure want to delete..?')")); ?>
</td>
<td id="rowUpdate">
<input type=checkbox name="editstudent[]" id="editstudent[]" value="<?php echo $row->id ?>">
</td>
<td ><input class="inputmedium span2" type="text" name="register_number_<?php echo $row->id ?>" id="register_number_<?php echo $row->id ?>" value="<?php echo $row->register_number; ?>" ></td>
<td ><input class="inputmedium span2" type="text" name="name_<?php echo $row->id ?>" id="name_<?php echo $row->id ?>" value="<?php echo $row->name; ?>" ></td>

<td >
<?php 

        $js = 'class="dropdown_class" id="course_code_id'.$row->id.'" onChange="get_subjectdetails112('.$row->id.')" '; 
        $js_name = 'course_code_id'.$row->id;
        echo form_dropdown($js_name, $data, $row->course_code, $js);
?>
</td>
<td>    

<?php 



        $js = 'class="dropdown_class" id="subject_code_id'.$row->id.'"'; 
        $js_name = 'subject_code_id'.$row->id;
        echo form_dropdown($js_name, $subject_data, $row->subject_code, $js);

?>





</td>

</tr>
<?php endforeach; ?>
</table>
</div>
<center>
<br /><input type="submit" class="btn-success btn" value="Update Student"></center>

<?php else : ?>
<h2>No records were returned.</h2>
<?php endif; ?>





view:student_update:

<script type="text/javascript" charset="utf-8">
function enableDisable(bEnable, textBoxID1, textBoxID2, chkBox)
{
    document.getElementById(textBoxID1).disabled = !bEnable
    document.getElementById(textBoxID2).disabled = !bEnable
    document.getElementById(chkBox).disabled = !bEnable
}
</script>

<script type="text/javascript" charset="utf-8">

 function get_subjectdetails112(index) {
 alert ("enter first");
    //var index = jQuery('#index').val();
    //alert("index"+index);
    var course_name = jQuery('#course_code_id'+index).val();
    alert("course_name"+course_name);
    //var exam_name = jQuery('#course_name_id>option:selected').text();
    var exam_name = jQuery('#exam_name_id').val();
    var ssubject_code = jQuery('#subject_code_id'+index).val();
    //var partsArray = exam_name.split('.');
    //alert("ssubject_code"+ssubject_code);
    //alert("course_name"+course_name);
    //alert("exam_name"+exam_name);
    jQuery.ajax({
        data: 'exam_name='+exam_name+'&course_name=' + course_name,
        type: 'POST',
        url: 'student_site/subject_records',
        success: function(data){
        //alert("inside change");
            console.log(data);
            //alert ("data"+data);
            //for(var j = course_name; j < ssubject_code; j++)
        //{
            jQuery('#subject_code_id'+index).empty().append(data);
        //}
        }

    });
} 
 function get_subjectdetails1(index) {
 alert ("enter first");
    //var index = jQuery('#index').val();
    //alert("index"+index);
    var course_name = jQuery('#course_name_id'+index).val();
    alert("course_name"+course_name);
    //var exam_name = jQuery('#course_name_id>option:selected').text();
    var exam_name = jQuery('#exam_name_id').val();
    var ssubject_code = jQuery('#ssubject_code'+index).val();
    //var partsArray = exam_name.split('.');
    //alert("ssubject_code"+ssubject_code);
    //alert("course_name"+course_name);
    //alert("exam_name"+exam_name);
    jQuery.ajax({
        data: 'exam_name='+exam_name+'&course_name=' + course_name,
        type: 'POST',
        url: 'student_site/subject_records',
        success: function(data){
        //alert("inside change");
            console.log(data);
            //alert ("data"+data);
            //for(var j = course_name; j < ssubject_code; j++)
        //{
            jQuery('#ssubject_code'+index).empty().append(data);
        //}
        }

    });
} 
 function student_updatedetails() {

        var register_number = jQuery('#register_number').val();
        var exam_name = jQuery('#exam_name_id').val();
        var name = jQuery('#name').val();
        var course_code = jQuery('#course_name_id').val();
        var subject_code = jQuery('#subject_name_id').val();
        //alert("register_number"+register_number+"name"+name+"exam_name: "+exam_name+"course_code"+course_code+"subject_code:"+subject_code);
        jQuery.ajax({
        data: 'exam_name=' + exam_name + '&register_number=' + register_number + '&name=' + name + '&course_code=' + course_code + '&subject_code=' + subject_code,
        type: 'POST',
        url: 'student_site/update',
        success: function(data){
            console.log(data);
            jQuery('#details').html(data);
        }
    });

} 

function CheckBoxVerification(From)
{
//alert('hi');
    if(From == "Insert")
    {
        if(!!$('#rowInsert input:checked').length == false)
        {
            alert('please select at least one check box to Create ...!');
        }
    }

    if(From == "Update")
    {
        if(!!$('#rowUpdate input:checked').length == false)
        {
            alert('please select at least one check box to Update ...!');
        }
    }
}
</script>




<br>
<div class="page-header">
    <h1 class="colored"><small><a>Create Student</a></small></h1>
  </div><br />
  <div class="well">
  <?php 
@$rcount=3;
//echo "rcount:".$rcount;
echo form_open('student_site/create_student/'.$rcount); ?>

<table>
<?php

  $j=1; 
  while($j<=$rcount)
  {
 ?>
<tr id="rowInsert">
<td>
<input type=checkbox name="createstudent[]" id="createstudent[]" onclick="enableDisable(this.checked, 'register_number_<?php echo $j ?>','name_<?php echo $j ?>', 'course_name_id<?php echo $j ?>');" value="<?php echo $j ?>">
</td>
<td><input type="text" id="register_number_<?php echo $j ?>" name="register_number_<?php echo $j ?>" required placeholder="Register_Number" class="span2" disabled="true"/></td>
<td><input type="text" id="name_<?php echo $j ?>" name="name_<?php echo $j ?>" onblur="ucwords(this)" placeholder="Name" required class="span2" disabled="true"/></td>

<?php
$cnt=0;
?>
<td>
  <?php 
        $data = array(
        );
        $data["Select Course Code"] = "Select Course Code";
        foreach ($course_records as $row)
        {

            $data[$row->course_code] = $row->course_code; 
        } 
        //echo form_dropdown('course_name', $data, 'small', 'class="dropdown_class span2" id="course_name_id" onChange="get_subjectdetails()"');

        $js = 'class="dropdown_class" id="course_name_id'.$j.'" onChange="get_subjectdetails1('.$j.')" disabled="true"'; 
        $js_name = 'course_name_id'.$j;
        echo form_dropdown($js_name, $data, 'small', $js);      
?>
<input type="hidden" name="index" id="index" value="<?php echo $j; ?>"/>

</td>
<td>
<div id="ssubject_code<?php echo $j; ?>" ></div>
<input type="hidden" name="ssubject_code" id="ssubject_code" value="ssubject_code<?php echo $j; ?>"/>
</td>
<?php 
   $j++;
  }
?>

</tr>
</table>
<input type="hidden" name="exam_name" id="exam_name" value="<?php echo $exam_name; ?>"/>
<input type="submit" value="Create Student" class="btn-success btn" onclick="CheckBoxVerification('Insert')"id="start_button"/>


</div>
<?php echo form_close(); ?>





<br />
</center>

Answer 1

拥有相关代码本来不错，而不是试图弄清楚代码的哪一部分应该填充框。我怀疑这是因为你试图将值插入选择框而不是遍历数组并逐个添加选项。这是我的一个应用程序中的一大块代码，用于清除下拉列表并使用新值重新填充它。值从服务器返回数组：AddressId =＆gt;地址

You should be able to see the parts that you need and modify it to your uses.

function loadAddresses()
{
    $.ajax({
        type: "POST",
        url: "/aj_getAddresses/",
        data: { companyId: $('#companyId').val() },
        dataType: "json",
        success: function(data) {
            if(data.status=="success")
            {
                $("#addressId").find('option').remove();

                $.each(data.addresses, function(key, val) {
                    $("#addressId").append(
                        '<option value="' + key + '">' + val + '</option>'
                    );
                });
            } else {
                $("#error").html(data.message);
            }
        },
        error: function(error) {
        }
    });
}