Question

我之前已经问过这个问题，但所有建议的解决方案都不起作用，所以我想改写它，我有一个html用户输入字段，它将数据发布到表单代码;

    #include <iostream>
#include <cstdlib>
using namespace std;

#include "QueueInt.h"

// Add an integer to the back of the queue.
void QueueInt::enqueue(int val)
{
  queueObj.push(val);
}

// Removes and returns an integer from the front of the queue. Aborts the
// program is the queue is empty.
int QueueInt::dequeue()
{
  int val = front();
  queueObj.pop();
  return val;
}

// Returns but does not remove the integer at the front of the queue. Aborts the
// program is the queue is empty.
int QueueInt::front() const
{
  if (isEmpty()) {
    cerr << "Tried to access empty queue --> aborting program" << endl;
    exit(-1);
  }

  return queueObj.front();
}

// Returns true if the queue is empty.
bool QueueInt::isEmpty() const
{
  return queueObj.empty();
}

然后存储在变量中，此变量用于选择并将DB的结果回显到select标记代码;

<form method="post" action="value1.php">

    <input id="nol" style="width: 350px;" type="text" name="searchdisease" placeholder="type diagnosis one">
<input class="btn btn-success" style="width: 120px; margin-right: -90%; margin-left: 9%;" type="submit" name="search" value="Search">
</form>

所以我想在用户输入为空时禁用上面的下拉列表

像：

<?php
 $search_disease = $_POST['searchdisease'];
                     $query="SELECT diagnosis, ICD10 FROM medications WHERE diagnosis LIKE '%$search_disease%'";
                     $result= $con->query($query);
    ?>

<select id="disease" style="width: 40%;  position: relative;top: 220px; left: 182px; " name="tdisease">
                            <option value="">Select Disease</option>
                             <?php while ($row=$result->fetch_array(MYSQLI_ASSOC)) { ?>
                            <option value="<?php echo $row['ICD10']?>"><?php echo $row['diagnosis'];?> </option> 
                      <?php } ?> 
                         </select>

但我不知道我可以在if语句中使用哪些代码

Answer 1

  Try this once...

  if($search_disease!=''){
    ?>

    <select id="disease" style="width: 40%;  position: relative;top: 220px; left: 182px; " name="tdisease">
                                <option value="">Select Disease</option>
                                 <?php while ($row=$result->fetch_array(MYSQLI_ASSOC)) { ?>
                                <option value="<?php echo $row['ICD10']?>"><?php echo $row['diagnosis'];?> </option> 
                          <?php } ?> 
                             </select>
    <?php } else { ?>
    <select id="disease" style="width: 40%;  position: relative;top: 220px; left: 182px; " name="tdisease" disable>
                                <option value="">Select Disease</option>
                                 <?php while ($row=$result->fetch_array(MYSQLI_ASSOC)) { ?>
                                <option value="<?php echo $row['ICD10']?>"><?php echo $row['diagnosis'];?> </option> 
                          <?php } ?> 
                             </select>
    <?php } ?>

Answer 2

html设置了一个不可见的部分：

<input type="hidden" id="aaa" value="$search_disease">

JS：

<script type="text/javascript">

window.onload=function(){

    var i = document.getElementById("aaa").value;

    if (i==''){

        document.getElementById("disease").style.display="none";
    }
}

如何根据字符串长度禁用HTML元素

2 个答案: