MySQL JSON Encoded string corrupts after INSERT..SELECT

Question

I'm encoding array of Image URLS into json string and store them in database. (utf8_general_ci).

When I insert data into table and retrive it, json_decode() is capable of decoding it.

However, when I copy data from one table to another (INSERT INTO ... SELECT statement) data after retrieving from database cannot be decoded anymore.

Instead, i get corrupted json ENCoded string. Even empty array [] cannot be properly decoded.

It converts from http://pl.tinypic.com/r/fwoiol/8 into http://pl.tinypic.com/r/bgea05/8

(had to make images since those squares cannot be copied as text).

Edit, After checking a bit more i tried to bin2hex() both strings from database.

Both seem to be exactly same.

However, one decodes and one does not. The

5b22687474703a5c2f5c2f7777772e
changes into
0022687474703a5c2f5c2f7777772e

So, json_decode only changes 5b into 00 in string.

It's like It's losing encoding somewhere?

Edit 2

static public function jsonDecodeFieldsArray($entries, $fields = array('features','images')){
    foreach($entries as $key => $entry){
        $entries[$key] = self::jsonDecodeFields($entry, $fields);
    }
    return $entries;
}
static public function jsonDecodeFields($entry, $fields = array('features','images')){
    foreach($fields as $field){
        if(isset($entry[$field])){
            $entry[$field] = json_decode((string) $entry[$field], true);
        }
    }
    return $entry;
}

I'm using code above, to decode keys of array specified by $fields. However, it not only decodes wrongfully. But also affects keys that are not listed in $fields. Corrupting their encodings.

More to add. If I dont use those functions and use only json_decode on fields json_decode($array[0][images], true) it works fine.

Answer 1

To Clarify that I found answer/solution I write this Answer

The reason behoind this error was not SQL error and data was proper. I had an example array of:

$many_entries = array(
    array(
        'features' = > 'json_encoded_string'
        'images' = > 'json_encoded_string'
    ),
    array(
        'features' = > 'json_encoded_string'
        'images' = > 'json_encoded_string'
    )

);
// And 
$one_entry = array(
    'features' = > 'json_encoded_string'
    'images' = > 'json_encoded_string'
);

Now I had 2 functions. One to Parse $many_entries ( jsonDecodeFieldsArray ) array and one to Parse $one_entry array structure ( jsonDecodeFields ).

The problem was I used jsonDecodeFieldsArray on $one_entry which made jsonDecodeFields iterate on strings.

Answer 2

It is odd that the character encoding is changing through the transmission. I would say check your charset(s) in PHP but you said the issue is only occurring in a table => table SQL transfer. I would still check the charset of the column / table.

You can fix the issue by running a str_replace() upon decoding. For example:

$DB_ARRAY = $DB_QUERY->fetch_array();
$CORRECT_ENCODING = json_decode(str_replace('0x93', '[', $DB_ARRAY['urlstring']), true);

You would, of course, need to know what the wrongly encoded character is. Or its ASCII code equivalent.