Question

我得到一个未定义的索引：每个超过一千的ID。我已经尝试了一切以使错误消失，并希望有人能够提供帮助。请提前致谢。

$ bamid是从页面调用的内容，它可以正常工作。错误来自此声明“$ selected [$ id]”，如果删除则没有错误。添加双引号或单引号不起作用。

<?
$sql="SELECT * users ORDER BY name ASC";
$result=mysql_query($sql);
$options = "";
while ($row=mysql_fetch_array($result))
{
$id = $row['id'];
$name = $row['name'];
$selected = array($bamid => "selected");
$options.="<option value = \"$id\" $selected[$id]>".$name.'</option>';
}
?>
<select name = "bamid">
<option>-------</option>
<? echo $options?>
</SELECT>

错误日志的示例输出：

[Sun Jun 30 01:46:55 2013] [warn] [client xx.xx.xx.xx] mod_fcgid: stderr: PHP Notice:  Undefined index: 572 in xxxxxxxxxxxxxxx on line 173

[Sun Jun 30 01:46:55 2013] [warn] [client xx.xx.xx.xx] mod_fcgid: stderr: PHP Notice:  Undefined index: 833 in xxxxxxxxxxxxxxx on line 173

[Sun Jun 30 01:46:55 2013] [warn] [client xx.xx.xx.xx] mod_fcgid: stderr: PHP Notice:  Undefined index: 698 in xxxxxxxxxxxxxxx on line 173

[Sun Jun 30 01:46:55 2013] [warn] [client xx.xx.xx.xx] mod_fcgid: stderr: PHP Notice:  Undefined index: 666 in xxxxxxxxxxxxxxx on line 173

[Sun Jun 30 01:46:55 2013] [warn] [client xx.xx.xx.xx] mod_fcgid: stderr: PHP Notice:  Undefined index: 546 in xxxxxxxxxxxxxxx on line 173

[Sun Jun 30 01:46:55 2013] [warn] [client xx.xx.xx.xx] mod_fcgid: stderr: PHP Notice:  Undefined index: 688 in xxxxxxxxxxxxxxx on line 173

[Sun Jun 30 01:46:55 2013] [warn] [client xx.xx.xx.xx] mod_fcgid: stderr: PHP Notice:  Undefined index: 834 in xxxxxxxxxxxxxxx on line 173

[Sun Jun 30 01:46:55 2013] [warn] [client xx.xx.xx.xx] mod_fcgid: stderr: PHP Notice:  Undefined index: 312 in xxxxxxxxxxxxxxx on line 173

[Sun Jun 30 01:46:55 2013] [warn] [client xx.xx.xx.xx] mod_fcgid: stderr: PHP Notice:  Undefined index: 650 in xxxxxxxxxxxxxxx on line 173

[Sun Jun 30 01:46:55 2013] [warn] [client xx.xx.xx.xx] mod_fcgid: stderr: PHP Notice:  Undefined index: 1109 in xxxxxxxxxxxxxxx on line 173

[Sun Jun 30 01:46:55 2013] [warn] [client xx.xx.xx.xx] mod_fcgid: stderr: PHP Notice:  Undefined index: 430 in xxxxxxxxxxxxxxx on line 173

Answer 1

如果当前$id等于$bamid，您的代码会尝试添加“已选中”，但所有其他情况中的代码是什么？它不知道，所以它会发出警告。

它仍然有效，因为未定义的字符串在PHP中呈现为空字符串，但最好明确说明。

<?
// BTW, this opening tag would be better as <?php

// #include standard recommendation on moving to PDO instead of deprecated MySQL
// support

while ($row=mysql_fetch_array($result))
{
    $id = $row['id'];
    $name = $row['name'];
    $selected = array($bamid => "selected");
    $options.="<option value = \"$id\" $selected[$id]>".$name.'</option>';
}

你可以这样做：

$selected = ($id == $bamid) ? 'selected="selected"' : '';
$options.="<option value=\"$id\" $selected>$name</option>";

或者，可能以牺牲重复为代价来制作更易读的代码：

if ($id == $bamid) {
    $options.= <<<OPTION_SELECTED

<option value="{$id}" selected="selected">{$name}</option>

OPTION_SELECTED;
} else {
    $options.= <<<OPTION_NOT_SELECTED

<option value="{$id}">{$name}</option>

OPTION_NOT_SELECTED;
}

如果你这么做了，你可能想要编写一个实用程序函数，它接受keys和values以及零个或多个选定键/值的数组，并返回组合的HTML框选项列表。这将导致

$optarr = array();
while ($row=mysql_fetch_array($result))
{
    $id   = $row['id'];
    $name = $row['name'];

    $optarr[$id] = $name;
}
mysql_free_result($result);

$options = htmlOptions($optarr, $bamid);

Answer 2

类似

$options.="<option value = \"$id\"";
if($bamid == $id) $options.= " selected";
$options.=">".$name.'</option>';

PHP上的未定义索引使用选中的下拉列表

2 个答案: