1、在 PHP 7.4 中报错：header() expects at least 1 parameter, 0 given。如图1
JSON
{
"errors": [
{
"debugMessage": "header() expects at least 1 parameter, 0 given",
"message": "Internal server error",
"extensions": {
"category": "internal"
},
"locations": [
{
"line": 5,
"column": 7
}
],
"path": [
"onlineStoreSession",
"versionedOnlineStore",
"theme"
],
"trace": [
{
"file": "E:\\wwwroot\\object\\Modules\\OnlineStoreThemeGraphQl\\Resolver\\OnlineStoreThemeResolver.php",
"line": 96,
"function": "header()"
},
{
"call": "Modules\\OnlineStoreThemeGraphQl\\Resolver\\OnlineStoreThemeResolver::Modules\\OnlineStoreThemeGraphQl\\Resolver\\{closure}(array(4), 'name')"
}
]
}
],
"data": {
"onlineStoreSession": {
"versionedOnlineStore": {
"theme": null
}
}
}
}
2、查看具体的代码实现
PHP
$fields = array_keys($resolveInfo->getFieldSelection());
return array_reduce($fields, function($carry, $field) use($fieldResolvers){
if (isset($fieldResolvers[$field])) {
$carry[$field] = is_callable($fieldResolvers[$field])? $fieldResolvers[$field](): $fieldResolvers[$field];
}
return $carry;
}, []);
3、打印 $fields ，结果如下
PHP
$fields = array_keys($resolveInfo->getFieldSelection());
print_r($fields);
exit;
Plaintext
Array
(
[0] => id
[1] => editable
[2] => createdAt
[3] => editedAt
[4] => name
[5] => role
[6] => previewable
[7] => url
[8] => themeStoreThemeId
[9] => metadata
[10] => presets
[11] => themeSettingsCategories
)
4、添加判断，当 $field 等于 name 时，打印 $fieldResolvers[$field]、is_callable($fieldResolvers[$field])
PHP
$fields = array_keys($resolveInfo->getFieldSelection());
return array_reduce($fields, function($carry, $field) use($fieldResolvers){
if (isset($fieldResolvers[$field])) {
if ($field == 'name') {
var_dump($fieldResolvers[$field]);
var_dump(is_callable($fieldResolvers[$field]));
exit;
}
$carry[$field] = is_callable($fieldResolvers[$field])? $fieldResolvers[$field](): $fieldResolvers[$field];
}
return $carry;
}, []);
Plaintext
string(6) "Header"
bool(true)
5、is_callable — 验证值是否可以在当前范围内作为函数调用。is_callable(‘Header’) 为 true，因为调用了 header() — 发送原生 HTTP 头，参数是必填的，进而报错。instanceof 用于确定一个 PHP 变量是否属于某一类 class 的实例。Closure 用于代表 匿名函数 的类。调整为 $fieldResolvers[$field] instanceof \Closure 后，不再报错。
PHP
$fields = array_keys($resolveInfo->getFieldSelection());
return array_reduce($fields, function($carry, $field) use($fieldResolvers){
if (isset($fieldResolvers[$field])) {
$carry[$field] = ($fieldResolvers[$field] instanceof \Closure) ? $fieldResolvers[$field](): $fieldResolvers[$field];
}
return $carry;
}, []);
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