如果我的表单已提交，我正在尝试回声。但是，什么也没有发生，而且我也没有任何错误。基本上，如果提交了第二个表单（仅在提交第一个表单时才显示），我想回显一条消息。这是行不通的。
任何帮助都会很棒。
update.php
<html>
<head>
</head>
<body>
<h2>Update Information</h2>
<form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="GET">
Person Number
<input type="number" name="number">
Last Name
<input type="text" name="lastname">
<button type="submit" name="submit">Search</button>
</form>
<?php
$xmlDocument=new DOMDocument;
$xmlDocument->preserveWhiteSpace=false;
$xmlDocument->load("person.xml");
$personXPath = new DOMXPath($xmlDocument);
if (isset($_GET["submit"])) {
$query = [];
if (!empty($_GET['number'])) {
$number = $_GET["number"];
$query[] = "@number='{$number}'";
}
if (!empty($_GET['lastname'])) {
$lastN = $_GET['lastname'];
$query[] = "./personL/fullname/lastname[contains(text(), '{$lastN}')]";
}
$query = '//personN[' . implode(' or ', $query) . ']';
$persons = $personXPath->query($query);
if ($persons->length > 0) {
foreach ($persons as $person) {
$firstname = $personXPath->evaluate('string(./personL/fullname/firstname/text())', $person);
$lastname = $personXPath->evaluate('string(./personL/fullname/lastname/text())', $person);
$eyecolor = $personXPath->evaluate('string(./personL/appearance/eye/text())', $person);
}?>
<form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="GET">
<h2>Edit Information</h2>
First Name:
<input type="text" name="efirstname" value="<?php echo $firstname ?>">
Last Name
<input type="text" name="elastname" value="<?php echo $lastname ?>">
Eye Color
<input type="text" name="eEyecolor" value="<?php echo $eyecolor ?>">
<button type="submit" name="change">Save</button>
</form>
<?php }
if (isset($_GET["change"])) {
echo "Yes";
} } ?>
</body>
</html>
几个错误：
$_GET['submit']在提交第二份表格时未设置。$query在提交第二种表单时将一无所获，因为第一种形式的字段不再提交给第二种表单。foreach循环仅循环分配，但不循环更新形式。所以我做了几处更改：
foreach循环中。我还重做了缩进，以便于阅读。
<html>
<head>
</head>
<body>
<h2>Update Information</h2>
<form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="GET">
Person Number
<input type="number" name="number" value="<?php echo $_GET['number'] ?? ''; ?>">
Last Name
<input type="text" name="lastname" value="<?php echo $_GET['lastname'] ?? ''; ?>">
<button type="submit" name="submit">Search</button>
</form>
<?php
$xmlDocument=new DOMDocument;
$xmlDocument->preserveWhiteSpace=false;
$xmlDocument->load("person.xml");
$personXPath = new DOMXPath($xmlDocument);
if (isset($_GET["submit"])) {
$query = [];
if (!empty($_GET['number'])) {
$number = $_GET["number"];
$query[] = "@number='{$number}'";
}
if (!empty($_GET['lastname'])) {
$lastN = $_GET['lastname'];
$query[] = "./personL/fullname/lastname[contains(text(), '{$lastN}')]";
}
$query = '//personN[' . implode(' or ', $query) . ']';
$persons = $personXPath->query($query);
?>
<?php if ($persons->length > 0) { ?>
<?php foreach ($persons as $person) { ?>
<?php
$firstname = $personXPath->evaluate('string(./personL/fullname/firstname/text())', $person);
$lastname = $personXPath->evaluate('string(./personL/fullname/lastname/text())', $person);
$eyecolor = $personXPath->evaluate('string(./personL/appearance/eye/text())', $person);
?>
<form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="GET">
<h2>Edit Information</h2>
First Name:
<input type="text" name="efirstname" value="<?php echo $firstname ?>">
Last Name
<input type="text" name="elastname" value="<?php echo $lastname ?>">
Eye Color
<input type="text" name="eEyecolor" value="<?php echo $eyecolor ?>">
<?php if (isset($number)) { ?>
<input type="hidden" name="number" value="<?php echo $number; ?>">
<?php } ?>
<?php if (isset($lastN)) { ?>
<input type="hidden" name="lastname" value="<?php echo $lastN; ?>">
<?php } ?>
<input type="hidden" name="submit" value="change">
<button type="submit" name="change">Save</button>
</form>
<?php } ?>
<?php } ?>
<?php if (isset($_GET["change"])) { ?>Yes<?php } ?>
<?php } ?>
</body>
</html>