检查 stdClass 对象在 PHP 中是否有“条目”
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Check if a stdClass object has "entries" in PHP
提问by ipalaus
I have a model that checks for entries en a database. Like this:
我有一个模型可以检查数据库中的条目。像这样：
public function getByID($id)
{
if(false == is_numeric($id))
return false;
$images = array();
$query = $this->db->where("id_album", $id)->order_by("order", "ASC")->get("images");
foreach($query->result() as $row)
$images[] = $row;
return (object) $images;
}
In my view I want to know if I have a rows or not, to show the images or not. I do this:
在我看来，我想知道我是否有一行，以显示图像。我这样做：
<?php if(false != isset($content->images)): ?>
<pre><?php print_r($content->images); ?></pre>
<?php endif; ?>
But every time I try to skip when I've no results (i get a stdClass() empty) I fail. I tried isset, $content->images != NULL, !$content->images... I don't know how to do it to skip the "Severity: Notice Message: Undefined variable".
但是每次当我没有结果时尝试跳过（我得到一个空的 stdClass()）我失败了。我试过isset，$content->images != NULL，!$content->images...我不知道该怎么做，以跳过“严重性：通知消息：未定义的变量”。
Thank you in advance.
先感谢您。
UPDATE:
更新：
$contenthas more sets than images, like $content->_dataor $content->title.
$content具有比图像更多的集合，例如$content->_data或$content->title。
When I've NO images on database and i've no return from MySQL, doing this:
当我在数据库上没有图像并且我没有从 MySQL 返回时，执行以下操作：
<?php echo count($content->images); ?>
<pre><?php print_r($content->images); ?></pre>
The output is:
输出是：
1
stdClass ( )
回答by RobertPitt
why cant you just use
为什么你不能使用
if(isset($content->images)) //Isset also will make sure $content is set
{
}
This way your performing checks on both entities.
这样您就可以对两个实体进行检查。
As images is an object that can be iterated you can also check that.
由于图像是可以迭代的对象，因此您也可以检查它。
if(isset($content->images) && is_object($content->images))
{
}
Also you seem to be using the wrong comparison operators for boolean's, you should be using the strict standards for comparison, which is ===and not ==, or !==and not !=:)
此外，您似乎对布尔值使用了错误的比较运算符，您应该使用严格的比较标准，即===and not==或!==not !=:)
Merry Christmas
圣诞节快乐
回答by lucifurious
I know this is an old question but it still hasn't been answered properly.
我知道这是一个老问题，但仍然没有得到正确回答。
issetonlytests if a key exists andnot if it is null. This is an important distinction. See the examples: http://us1.php.net/isset
isset只测试键是否存在，而不测试它是否为空。这是一个重要的区别。查看示例：http: //us1.php.net/isset
To properly test if an array contains a key, array_key_existsshould be used as stated elsewhere on this page.
要正确测试数组是否包含键，array_key_exists应按照本页其他地方的说明使用。
On the other hand, to test if an object contains a property, the property_existsmethod should be used. property_exists()returns TRUEeven if the property has a NULLvalue.
另一方面，要测试对象是否包含属性，property_exists应该使用该方法。即使该属性具有值也property_exists()返回。TRUENULL
So, your code should look like this (yeah, I changed it a bit but the point remains the same):
因此，您的代码应如下所示（是的，我对其进行了一些更改，但要点保持不变）：
<?php
if ( isset( $content ) && property_exists( $content, 'images' ) ) {
echo '<pre>' . print_r( $content->images, true ) . '</pre>';
}
?>
回答by Damien Overeem
Ran into this question/answers while trying to find out how to check for an empty stdClass.
在尝试找出如何检查空 stdClass 时遇到了这个问题/答案。
The given answers are not really answers to the question in the topic, leading people here that wont get a clear answer, so I'll add an improved version:
给出的答案并不是主题中问题的真正答案，导致这里的人不会得到明确的答案，因此我将添加一个改进版本：
Question:Check if a stdClass object has “entries” in PHP
问题：检查一个 stdClass 对象在 PHP 中是否有“条目”
Answer:
回答：
Typecast the stdClass to array, see below:
将 stdClass 类型转换为数组，见下文：
$someObject = new StdClass();
var_dump(empty($someObject)); // Will return false, because $someObject is an stdClass
// Convert to array
$someObjectArr = (array)$someObject;
var_dump(empty($someObjectArray)); // Will return true
回答by Jacob Relkin
回答by ironchicken
I wanted to check if some object has allof the given properties. So I did this:
我想检查某个对象是否具有所有给定的属性。所以我这样做了：
function hasAllProperties($object, array $properties) {
return array_reduce(
$properties,
function ($acc, $property) use ($object) {
return $acc && property_exists($object, $property);
},
true
);
};
$someObject = json_decode('{"foo": "bar", "baz": "quux"}');
echo 'should be true ' . (hasAllProperties($someObject, ['foo', 'baz']) ? 'TRUE' : 'FALSE') . "\n";
echo 'should be false ' . (hasAllProperties($someObject, ['foo', 'baz', 'moo']) ? 'TRUE' : 'FALSE') . "\n";
echo 'should be false ' . (hasAllProperties($someObject, ['foo', 'moo']) ? 'TRUE' : 'FALSE') . "\n";
Then in addition you may also want to check if just one or more of the properties exists:
此外，您可能还想检查是否仅存在一个或多个属性：
function hasAnyProperties($object, array $properties) {
return array_reduce(
$properties,
function ($acc, $property) use ($object) {
return $acc || property_exists($object, $property);
},
false
);
};
$someObject = json_decode('{"foo": "bar", "baz": "quux"}');
echo 'should be true ' . (hasAnyProperties($someObject, ['foo', 'baz']) ? 'TRUE' : 'FALSE') . "\n";
echo 'should be true ' . (hasAnyProperties($someObject, ['foo', 'baz', 'moo']) ? 'TRUE' : 'FALSE') . "\n";
echo 'should be true ' . (hasAnyProperties($someObject, ['foo', 'moo']) ? 'TRUE' : 'FALSE') . "\n";
echo 'should be false ' . (hasAnyProperties($someObject, ['moo']) ? 'TRUE' : 'FALSE') . "\n";
回答by CyrilRegal
If i want to test the whole object to know if i do something or not i proced like that:
如果我想测试整个对象以了解我是否做了某事，我会这样做：
if($object != new stdClass())
{
// do something
}
