Asked  8 Months ago    Answers:  5   Viewed   124 times

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.

 Answers

27

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:

  • 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).

  • In PHP, you can use the default_charset php.ini option, or manually issue the Content-Type MIME header yourself, which is just more work but has the same effect.

  • When encoding the output using json_encode(), add JSON_UNESCAPED_UNICODE as a second parameter.

Input:

  • Unfortunately, you should 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.

  • From my reading of the current HTML spec, the following sub-bullets are not necessary or even valid anymore for modern HTML. My understanding is that browsers will work with and submit data in the character set specified for the document. However, if you're targeting older versions of HTML (XHTML, HTML4, etc.), these points may still be useful:

    • For HTML before HTML5 only: you want all data sent to you by browsers to be in UTF-8. Unfortunately, if you go by the only way to reliably do this is add the accept-charset attribute to all your <form> tags: <form ... accept-charset="UTF-8">.
    • For HTML before HTML5 only: note that the W3C HTML spec says that clients "should" default to sending forms back to the server in whatever charset the server served, but this is apparently only a recommendation, hence the need for being explicit on every single <form> tag.

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.

Wednesday, March 31, 2021
 
kwichz
answered 8 Months ago
51

Get rid of the hyphen. It should be:

mysql_query("SET NAMES utf8");
Wednesday, March 31, 2021
 
TMichel
answered 8 Months ago
37

It looks like you have a normalization problem in your database. Instead of storing the same state as string over and over again, put all state names into a table of it's own and reference them.

This will also ensure that you do not - e.g. by accident - put binary different but equally looking data into different rows you're not able to properly align later on as you just did.

Alternatively you should query distinct rows and update them, so that you do at least have the same binary string data for same-named states. E.g. if Mysql is able to actually align these state strings but PHP - due to it's binary nature of strings - is not.

Saturday, May 29, 2021
 
Nickool
answered 5 Months ago
36

That depends on where you use it...

The name of the encoding is UTF-8.

A dash is not valid to use everywhere, so for example in .NET framework the property of the System.Text.Encoding class that returns an instance of the UTF8Encoding class that handles the UTF-8 encoding is named UTF8.

Monday, August 2, 2021
 
Skipper
answered 3 Months ago
100

Check out Joel Spolsky's The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!)

EDIT 20140523: Also, watch Characters, Symbols and the Unicode Miracle by Tom Scott on YouTube - it's just under ten minutes, and a wonderful explanation of the brilliant 'hack' that is UTF-8

Saturday, September 4, 2021
 
Xun Yang
answered 2 Months ago
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