[英]Encoding a single key in associative array to base64
I am trying to retrieve user data from a SQL table where one of the columns is blob_medium.我试图从其中一列是 blob_medium 的 SQL 表中检索用户数据。 I run the SQL query properly and get the data in the php script.我正确运行 SQL 查询并在 php 脚本中获取数据。
if(mysqli_num_rows($result)){
while($row=mysqli_fetch_assoc($result)){
$result_array['user_data'][]=$row;
}
}
Now, to json_encode this data, I need to encode the data of user_pic column to base 64. For that I am trying this.现在,要对这些数据进行 json_encode,我需要将 user_pic 列的数据编码为 base 64。为此,我正在尝试这样做。 But, it seems I am doing something wrong.但是,似乎我做错了什么。 Any kind of help would be appreciated.任何形式的帮助将不胜感激。
foreach($result_array as $key){
foreach($key as $key2){
//print_r(base64_encode($key2['user_pic']).'<br/>'.'<br/>');
$key2['user_pic'] = base64_encode($key['user_pic']);
//print_r(($key['user_pic']).'<br/>'.'<br/>');
}
}
When I uncomment the print_r statements my data is printed in base64 format but the data of the assoc array is not changing.当我取消对 print_r 语句的注释时,我的数据以 base64 格式打印,但 assoc 数组的数据没有改变。
That's because the array's $key
and $keys
in the for loop are copies.那是因为在 for 循环中数组的$key
和$keys
是副本。 If you want them to modify the original you can either do it by specifying them to be references, not copies:如果您希望他们修改原件,您可以通过将它们指定为参考而不是副本来实现:
foreach($result_array['user_data'] as &$key){
$key['user_pic'] = base64_encode($key['user_pic']);
}
Or by explicit index into the original:或者通过显式索引到原始:
foreach($result_array['user_data'] as $index => $key){
$result_array['user_data'][$index] ['user_pic'] = base64_encode($key['user_pic']);
}
That's because you're changing the $key2
array.那是因为您正在更改$key2
数组。 A temporary value created by your foreach
loop.由您的foreach
循环创建的临时值。 I myself would recommend using a for
loop in this specific situation, because I was told to never use a loop within a loop if I can prevent it, and it makes things a lot easier to read:我自己会建议在这种特定情况下使用for
循环,因为有人告诉我,如果可以防止的话,永远不要在循环中使用循环,并且它使事情更容易阅读:
for($i=0; $i < count($result_array['user_data']); $i++){
$encodedUserPic = base64_encode($result_array['user_data'][$i]['user_pic']);
$result_array['user_data'][$i]['user_pic'] = $encodedUserPic;
}
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