I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.
Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?
This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.
Data Storage:
Specify the utf8mb4 character set on all tables and text columns in your database. This makes MySQL physically store and retrieve values encoded natively in UTF-8. Note that MySQL will implicitly use utf8mb4 encoding if a utf8mb4_* collation is specified (without any explicit character set).
In older versions of MySQL (< 5.5.3), you'll unfortunately be forced to use simply utf8, which only supports a subset of Unicode characters. I wish I were kidding.
Data Access:
In your application code (e.g. PHP), in whatever DB access method you use, you'll need to set the connection charset to utf8mb4. This way, MySQL does no conversion from its native UTF-8 when it hands data off to your application and vice versa.
Some drivers provide their own mechanism for configuring the connection character set, which both updates its own internal state and informs MySQL of the encoding to be used on the connection—this is usually the preferred approach. In PHP:
If you're using the PDO abstraction layer with PHP ≥ 5.3.6, you can specify charset in the DSN:
$dbh = new PDO('mysql:charset=utf8mb4');
If you're using mysqli, you can call set_charset():
$mysqli->set_charset('utf8mb4'); // object oriented style
mysqli_set_charset($link, 'utf8mb4'); // procedural style
If you're stuck with plain mysql but happen to be running PHP ≥ 5.2.3, you can call mysql_set_charset.
If the driver does not provide its own mechanism for setting the connection character set, you may have to issue a query to tell MySQL how your application expects data on the connection to be encoded: SET NAMES 'utf8mb4'.
The same consideration regarding utf8mb4/utf8 applies as above.
Output:
UTF-8 should be set in the HTTP header, such as Content-Type: text/html; charset=utf-8. You can achieve that either by setting default_charset in php.ini (preferred), or manually using header() function.
If your application transmits text to other systems, they will also need to be informed of the character encoding. With web applications, the browser must be informed of the encoding in which data is sent (through HTTP response headers or HTML metadata).
When encoding the output using json_encode(), add JSON_UNESCAPED_UNICODE as a second parameter.
Input:
Browsers will submit data in the character set specified for the document, hence nothing particular has to be done on the input.
In case you have doubts about request encoding (in case it could be tampered with), you may verify every received string as being valid UTF-8 before you try to store it or use it anywhere. PHP's mb_check_encoding() does the trick, but you have to use it religiously. There's really no way around this, as malicious clients can submit data in whatever encoding they want, and I haven't found a trick to get PHP to do this for you reliably.
Other Code Considerations:
Obviously enough, all files you'll be serving (PHP, HTML, JavaScript, etc.) should be encoded in valid UTF-8.
You need to make sure that every time you process a UTF-8 string, you do so safely. This is, unfortunately, the hard part. You'll probably want to make extensive use of PHP's mbstring extension.
PHP's built-in string operations are not by default UTF-8 safe. There are some things you can safely do with normal PHP string operations (like concatenation), but for most things you should use the equivalent mbstring function.
To know what you're doing (read: not mess it up), you really need to know UTF-8 and how it works on the lowest possible level. Check out any of the links from utf8.com for some good resources to learn everything you need to know.
I'd like to add one thing to chazomaticus' excellent answer:
Don't forget the META tag either (like this, or the HTML4 or XHTML version of it):
<meta charset="utf-8">
That seems trivial, but IE7 has given me problems with that before.
I was doing everything right; the database, database connection and Content-Type HTTP header were all set to UTF-8, and it worked fine in all other browsers, but Internet Explorer still insisted on using the "Western European" encoding.
It turned out the page was missing the META tag. Adding that solved the problem.
Edit:
The W3C actually has a rather large section dedicated to I18N. They have a number of articles related to this issue – describing the HTTP, (X)HTML and CSS side of things:
FAQ: Changing (X)HTML page encoding to UTF-8
Declaring character encodings in HTML
Tutorial: Character sets & encodings in XHTML, HTML and CSS
Setting the HTTP charset parameter
They recommend using both the HTTP header and HTML meta tag (or XML declaration in case of XHTML served as XML).
In addition to setting default_charset in php.ini, you can send the correct charset using header() from within your code, before any output:
header('Content-Type: text/html; charset=utf-8');
Working with Unicode in PHP is easy as long as you realize that most of the string functions don't work with Unicode, and some might mangle strings completely. PHP considers "characters" to be 1 byte long. Sometimes this is okay (for example, explode() only looks for a byte sequence and uses it as a separator -- so it doesn't matter what actual characters you look for). But other times, when the function is actually designed to work on characters, PHP has no idea that your text has multi-byte characters that are found with Unicode.
A good library to check into is phputf8. This rewrites all of the "bad" functions so you can safely work on UTF8 strings. There are extensions like the mb_string extension that try to do this for you, too, but I prefer using the library because it's more portable (but I write mass-market products, so that's important for me). But phputf8 can use mb_string behind the scenes, anyway, to increase performance.
Warning: This answer applies to PHP 5.3.5 and lower. Do not use it for PHP version 5.3.6 (released in March 2011) or later.
Compare with Palec's answer to PDO + MySQL and broken UTF-8 encoding.
I found an issue with someone using PDO and the answer was to use this for the PDO connection string:
$pdo = new PDO(
'mysql:host=mysql.example.com;dbname=example_db',
"username",
"password",
array(PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"));
In my case, I was using mb_split, which uses regular expressions. Therefore I also had to manually make sure the regular expression encoding was UTF-8 by doing mb_regex_encoding('UTF-8');
As a side note, I also discovered by running mb_internal_encoding() that the internal encoding wasn't UTF-8, and I changed that by running mb_internal_encoding("UTF-8");.
First of all, if you are in PHP before 5.3 then no. You've got a ton of problems to tackle.
I am surprised that none has mentioned the intl library, the one that has good support for Unicode, graphemes, string operations, localisation and many more, see below.
I will quote some information about Unicode support in PHP by Elizabeth Smith's slides at PHPBenelux'14
INTL
Good:
Wrapper around ICU library
Standardised locales, set locale per script
Number formatting
Currency formatting
Message formatting (replaces gettext)
Calendars, dates, time zone and time
Transliterator
Spoofchecker
Resource bundles
Convertors
IDN support
Graphemes
Collation
Iterators
Bad:
Does not support zend_multibyte
Does not support HTTP input output conversion
Does not support function overloading
mb_string
Enables zend_multibyte support
Supports transparent HTTP in/out encoding
Provides some wrappers for functionality such as strtoupper
ICONV
Primary for charset conversion
Output buffer handler
mime encoding functionality
conversion
some string helpers (len, substr, strpos, strrpos)
Stream Filter stream_filter_append($fp, 'convert.iconv.ISO-2022-JP/EUC-JP')
DATABASES
MySQL: Charset and collation on tables and on the connection (not the collation). Also, don't use mysql - mysqli or PDO
postgresql: pg_set_client_encoding
sqlite(3): Make sure it was compiled with Unicode and intl support
Some other gotchas
You cannot use Unicode filenames with PHP and windows unless you use a 3rd part extension.
Send everything in ASCII if you are using exec, proc_open and other command line calls
Plain text is not plain text, files have encodings
You can convert files on the fly with the iconv filter
The only thing I would add to these amazing answers is to emphasize on saving your files in UTF-8 encoding, I have noticed that browsers accept this property over setting UTF-8 as your code encoding. Any decent text editor will show you this. For example, Notepad++ has a menu option for file encoding, and it shows you the current encoding and enables you to change it. For all my PHP files I use UTF-8 without a BOM.
Sometime ago I had someone ask me to add UTF-8 support for a PHP and MySQL application designed by someone else. I noticed that all files were encoded in ANSI, so I had to use iconv to convert all files, change the database tables to use the UTF-8 character set and utf8_general_ci collate, add 'SET NAMES utf8' to the database abstraction layer after the connection (if using 5.3.6 or earlier. Otherwise, you have to use charset=utf8 in the connection string) and change string functions to use the PHP multibyte string functions equivalent.
I recently discovered that using strtolower() can cause issues where the data is truncated after a special character.
The solution was to use
mb_strtolower($string, 'UTF-8');
mb_ uses MultiByte. It supports more characters but in general is a little slower.
In PHP, you'll need to either use the multibyte functions, or turn on mbstring.func_overload. That way things like strlen will work if you have characters that take more than one byte.
You'll also need to identify the character set of your responses. You can either use AddDefaultCharset, as above, or write PHP code that returns the header. (Or you can add a META tag to your HTML documents.)
I have just gone through the same issue and found a good solution at PHP manuals.
I changed all my files' encoding to UTF8 and then the default encoding on my connection. This solved all the problems.
if (!$mysqli->set_charset("utf8")) {
printf("Error loading character set utf8: %s\n", $mysqli->error);
} else {
printf("Current character set: %s\n", $mysqli->character_set_name());
}
View Source
Unicode support in PHP is still a huge mess. While it's capable of converting an ISO 8859 string (which it uses internally) to UTF-8, it lacks the capability to work with Unicode strings natively, which means all the string processing functions will mangle and corrupt your strings.
So you have to either use a separate library for proper UTF-8 support, or rewrite all the string handling functions yourself.
The easy part is just specifying the charset in HTTP headers and in the database and such, but none of that matters if your PHP code doesn't output valid UTF-8. That's the hard part, and PHP gives you virtually no help there. (I think PHP 6 is supposed to fix the worst of this, but that's still a while away.)
If you want a MySQL server to decide the character set, and not PHP as a client (old behaviour; preferred, in my opinion), try adding skip-character-set-client-handshake to your my.cnf, under [mysqld], and restart mysql.
This may cause trouble in case you're using anything other than UTF-8.
The top answer is excellent. Here is what I had to on a regular Debian, PHP, and MySQL setup:
// Storage
// Debian. Apparently already UTF-8
// Retrieval
// The MySQL database was stored in UTF-8,
// but apparently PHP was requesting ISO 8859-1. This worked:
// ***notice "utf8", without dash, this is a MySQL encoding***
mysql_set_charset('utf8');
// Delivery
// File *php.ini* did not have a default charset,
// (it was commented out, shared host) and
// no HTTP encoding was specified in the Apache headers.
// This made Apache send out a UTF-8 header
// (and perhaps made PHP actually send out UTF-8)
// ***notice "utf-8", with dash, this is a php encoding***
ini_set('default_charset','utf-8');
// Submission
// This worked in all major browsers once Apache
// was sending out the UTF-8 header. I didn’t add
// the accept-charset attribute.
// Processing
// Changed a few commands in PHP, like substr(),
// to mb_substr()
That was all!
What I'm trying to do is grab some text in my web application (string literals containing non English characters such as ă) with Javascript. Pass it to an object and then use JSON.Stringify() on the object, and then pass that to a python script.
The Python script is intended to load the json data and eventually print the text on a POS printer so the final data has to be in ascii hex format of a specific code page which means ill have to perform some character conversion either before or after the python script gets the data.
Basically something like this:
someObject.arrayOfTextInputs.push("how can I handle the ă character");
--run a python script and pass to it: JSON.Stringify(someObject) --
In Python:
jsonStuff = sys.argv[1]
myObject= json.loads(jsonStuff)
Now if I simply pass the strings as is, the python script hangs upon json.loads because of the ă character. If i replace the character prior to Stringify, with an'\xNN' representation matching a value from a Code Page i need, the json.loads still hangs.
Same thing for using '\uNNNN'.
I also printed out the json i get before handing it over to json.loads() and normally it just prints out some weird hex? character/image instead of ă.
However, replacing it to its utf-8 repesentation (in javascript) \xc4\x83, makes the print in python display the character properly (altho it creates problems in the next steps).
Same thing happens with replacing ă with \xC7 which is the matching character in code page 852 (latin-2) and then jsonStuff.decode('cp852')
What are my options here?
Edit: Thanks for the welcome!
I am using Python 2.7 which from what I've gathered uses standard ascii encoding.
If i skip any conversion i get the exception: ValueError: Invalid control character at some character/byte..
If I convert the character in Javascript (before doing Stringify() on the object) with an escape matching the same character from an utf-8 table: "\u0103" i get the same exception.
If I convert the character to some utf-8 character that falls into the standard ascii character set ("\u0045"), it loads fine. I guess the decoder can automatically map the unicode "regular" characters into their ascii representatives.
Same thing for converting to say "\x45".
If I add strict=False argument to the loads() function, i can load any escaped character but then I'm not sure how to handle it in my python script.
I have to admit, the stringify and loads() part really makes me lose track, since I'm starting out with utf8 in my IDE, using escape characters from a different encoding, then calling stringify (only utf8 encoded stuff is valid json?) and pass it into python which cant handle utf8 past the standard character set. And I have to end up with '\xNN' of a specific code page(say Latin-2) in the end just before the print.
Should I try to pass anything using strict=False and handle it from there within python, or is it possible to send everything encoded using some code page?
I'll add some code in a bit.
I have a long json array that needs to be sent to an html5 mobile app and parsed. The whole array has around 700kb (gziped to 150kb) and it's 554976 characters long at the moment. But it will increase on time.
Using jquery to parse the json, my app crashes while trying to parse it. And so does jsonlint, json parser.fr and any other online json validator I try, so I'm guessing eval() is not an option either.
Might be a broad question but what is the maximum "acceptable" length for a json array?
I have already removed as much data as I can from the array, the only option I can think of is to split the array in 3-4 server calls and parse it separately in the app. Is there any other option?
EDIT
Thanks to #fabien for pointing that if jsonlint crashes there is a problem on the json. There was a hidden "space" character in one of the nodes. It was parsed correctly on the server but not on the client.
I've parsed way bigger arrays with jquery.
My first guess is that there's an error in your json.
You have many ways to find it (sublime text could highlight the error but some time, it's a bit long). Try to paste it in a web tool like http://www.jsoneditoronline.org/. and use any of the buttons (to format or to send to the right view). It'll tell you where the error is.
I'm parsing a 2MB JSON string in IE8. The JSON.Parse line is taking a little while to return and IE8 shows a message asking the user if they want to abort the script.
Is there any way I can suppress this message? (or somehow speed up JSON.Parse)
I know about Microsoft KB175500, however this is not suitable as my target users will not have administrator access to make the registry modifications on their SOE machines.
I had this same question. Apparently there is no way to suppress the message, but there are tricks to make IE think it's still working by using an asynchronous iteration pattern (dead link, view comments below).
This comes from an answer to one of my questions:
loop is too slow for IE7/8
If the browser is unhappy with how long the JSON parser is taking, there are only four choices here I know of:
Get a faster JSON parser that doesn't take so long.
Break up your JSON data into smaller pieces so you are only parsing smaller pieces at once.
Modify a JSON parser to work in chunks so it can parse part of the data in one chunk, then on a short timeout, parse the next chunk, etc... This will prevent the browser prompt, but is probably a lot of work to write/modify a JSON parser that works this way.
If you can be sure the content is safe, then you could see if using eval instead of a JSON parser works around the issue.