php 为什么 json_encode 会返回一个空字符串
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/19361282/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Why would json_encode return an empty string
提问by Matthieu Riegler
I have a simple php structure with 3 nested arrays.
我有一个带有 3 个嵌套数组的简单 php 结构。
I do not use particular objects and I build myself the arrays with 2 nested loops.
我不使用特定对象，而是使用 2 个嵌套循环为自己构建数组。
Here is a sample of the var_dump of the array I want to convert to Json.
这是我要转换为 Json 的数组的 var_dump 示例。
array (size=2)
'tram B' =>
array (size=2)
0 =>
array (size=3)
'name' => string 'Ile Verte' (length=9)
'distance' => int 298
'stationID' => int 762
1 =>
array (size=3)
'name' => string 'La Tronche H?pital' (length=18)
'distance' => int 425
'stationID' => int 771
16 =>
array (size=4)
0 =>
array (size=3)
'name' => string 'Bastille' (length=8)
'distance' => int 531
'stationID' => int 397
1 =>
array (size=3)
'name' => string 'Xavier Jouvin' (length=13)
'distance' => int 589
'stationID' => int 438
In another script I have a similar structure and json_encodeworks fine.
So I don't understand why json_encodewon't work here.
在另一个脚本中，我有一个类似的结构并且json_encode工作正常。所以我不明白为什么json_encode不能在这里工作。
Edit : there seems to be a problem with the encoding. When mb_detect_encodingreturns ASCII, the json_encodeworks but when it returns UTF8, it doesn't work anymore.
编辑：编码似乎有问题。当mb_detect_encoding返回 ASCII 时，json_encode工作但当它返回 UTF8 时，它不再工作。
Edit2 : json_last_error()returns JSON_ERROR_UTF8which means : Malformed UTF-8 characters, possibly incorrectly encoded.
Edit2：json_last_error()返回JSON_ERROR_UTF8这意味着：格式错误的 UTF-8 字符，可能编码不正确。
回答by Matthieu Riegler
Well after 2 hours of digging (cf Edits)
经过 2 小时的挖掘（参见编辑）
I found out following :
我发现以下内容：
- In my case it's a encoding problem
mb_detect_encodingreturns probably a faulty response, some strings were probably not UTF-8- using
utf8_encode()on those string solved my problem, but see note below
- 就我而言，这是一个编码问题
mb_detect_encoding可能返回错误响应，某些字符串可能不是 UTF-8utf8_encode()在这些字符串上使用解决了我的问题，但请参阅下面的注释
Here is a recursive function that can force convert to UTF-8 all the strings contained in an array:
这是一个递归函数，可以强制将数组中包含的所有字符串转换为 UTF-8：
function utf8ize($d) {
if (is_array($d)) {
foreach ($d as $k => $v) {
$d[$k] = utf8ize($v);
}
} else if (is_string ($d)) {
return utf8_encode($d);
}
return $d;
}
Use it simply like this:
像这样简单地使用它：
echo json_encode(utf8ize($data));
Note: utf8_encode()encodes ISO-8859-1 string to UTF-8 as per the docs so if you are unsure of the input encoding iconv()or mb_convert_encoding()may be better options as noted in comments and other solutions.
注意：utf8_encode()根据文档将 ISO-8859-1 字符串编码为 UTF-8，因此如果您不确定输入编码iconv()或mb_convert_encoding()可能是更好的选择，如注释和其他解决方案中所述。
回答by Adam Bubela
Matthieu Riegler presented really good solution however I had to slightly modify it to handle objects too:
Matthieu Riegler 提出了非常好的解决方案，但是我不得不稍微修改它以处理对象：
function utf8ize($d) {
if (is_array($d))
foreach ($d as $k => $v)
$d[$k] = utf8ize($v);
else if(is_object($d))
foreach ($d as $k => $v)
$d->$k = utf8ize($v);
else
return utf8_encode($d);
return $d;
}
One more note: json_last_error()may be helpful in debugging json_encode()/json_encode() functions.
再注意一点：json_last_error()可能有助于调试 json_encode()/json_encode() 函数。
回答by fayd
For me, the answer to this problem was setting charset=utf8in my PDO connection.
对我来说，这个问题的答案是charset=utf8在我的 PDO 连接中设置。
$dbo = new PDO('mysql:host=localhost;dbname=yourdb;charset=utf8', $username, $password);
回答by Alex
Adam Bubela also presented really good solution who helped me solved my problem, and here is the simplified function :
Adam Bubela 还提出了非常好的解决方案，他帮助我解决了我的问题，这是简化的功能：
function utf8ize($d)
{
if (is_array($d) || is_object($d))
foreach ($d as &$v) $v = utf8ize($v);
else
return utf8_encode($d);
return $d;
}
回答by Vsevolod Azovsky
I have exactly the same problem on PHP 5.6. I use Open Server+ Nginx on Windows 7. All charsets are set to UTF-8. In theory, according the official documentation, flag
我在 PHP 5.6 上有完全相同的问题。我在 Windows 7 上使用Open Server+ Nginx。所有字符集都设置为 UTF-8。理论上，根据官方文档，flag
JSON_UNESCAPED_UNICODE
JSON_UNESCAPED_UNICODE
should solve this. Unfortunately this is not my case. I do not know, why. All snippets above do not solve my problem, thus I have found my own implementation. I believe it could help someone. At least, Russian letters pass the test.
应该解决这个问题。不幸的是，这不是我的情况。我不知道为什么。上面的所有片段都没有解决我的问题，因此我找到了自己的实现。我相信它可以帮助某人。至少，俄文字母通过了测试。
function utf8ize($d) {
if (is_array($d) || is_object($d)) {
foreach ($d as &$v) $v = utf8ize($v);
} else {
$enc = mb_detect_encoding($d);
$value = iconv($enc, 'UTF-8', $d);
return $value;
}
return $d;
}
回答by Kholofelo
This accepted answer works. But in case you are getting your data from MySQL (as I was) there is an easier way.
这个接受的答案有效。但是，如果您从 MySQL 获取数据（就像我一样），有一种更简单的方法。
Once you open you database, before you query you can set the character set using mysqli as follows:
打开数据库后，在查询之前，您可以使用 mysqli 设置字符集，如下所示：
/* change character set to utf8 | Procedural*/
if (!mysqli_set_charset($link, "utf8")) {
printf("Error loading character set utf8: %s\n", mysqli_error($link));
exit();
}
OR
或者
/* change character set to utf8 | Object Oriented*/
if (!$mysqli->set_charset("utf8")) {
printf("Error loading character set utf8: %s\n", $mysqli->error);
exit();
}
回答by Shane N
I ran into this issue on a server running an older version of PHP (5.2). I was using the JSON_FORCE_OBJECT flag, and apparently that isn't supported until 5.3
我在运行旧版本 PHP (5.2) 的服务器上遇到了这个问题。我使用的是 JSON_FORCE_OBJECT 标志，显然直到 5.3 才支持
So if you're using that flag be sure to check your version!
因此，如果您正在使用该标志，请务必检查您的版本！
A workaround appears to be just casting to an object before encoding, like:
解决方法似乎只是在编码之前转换为对象，例如：
json_encode((object)$myvar);
回答by cmbuckley
The return of mb_detect_encodingmay not be correct:
的返回mb_detect_encoding可能不正确：
$data = iconv('UTF-8', 'ISO-8859-1', 'La Tronche H?pital');
var_dump(
mb_detect_encoding($data),
mb_detect_encoding($data, array('ISO-8859-1', 'UTF-8'))
);
Depending on the default detection order, the above may return different results, so the encoding is falsely being reported as UTF-8. (Here's a larger example.)
根据默认的检测顺序，上面可能会返回不同的结果，因此编码被错误地报告为 UTF-8。（这是一个更大的例子。）
It is likely that your data is not encoded as UTF-8, so json_encodeis returning false. You should look at converting your strings to UTF-8 before JSON-encoding:
您的数据可能未编码为 UTF-8，因此json_encode返回false. 在 JSON 编码之前，您应该考虑将字符串转换为 UTF-8：
$fromEncoding = 'ISO-8859-1'; // This depends on the data
array_walk_recursive($array, function (&$value, $key, $fromEncoding) {
if (is_string($value)) {
$value = iconv($fromEncoding, 'UTF-8', $value);
}
}, $fromEncoding);
回答by zdeniiik
I was getting data from ob_get_clean() and had the same problem, but above solutions don't work for me. In my case solution was this, maybe it will help somebody.
我正在从 ob_get_clean() 获取数据并遇到同样的问题，但上述解决方案对我不起作用。在我的情况下，解决方案是这样的，也许它会帮助某人。
$var = mb_convert_encoding($var, 'UTF-8');
回答by mobizen
using utf8_encode() on those string solved my problem.
在这些字符串上使用 utf8_encode() 解决了我的问题。
