json_encode is returning NULL?

Question

For some reason the item "description" returns NULL with the following code:

<?php
include('db.php');

$result = mysql_query('SELECT * FROM `staff` ORDER BY `id` DESC LIMIT 2') or die(mysql_error());
$rows = array();
while($row = mysql_fetch_assoc($result)){
    $rows[] = $row;
}

echo json_encode($rows);
?>

Here is the schema for my database:

CREATE TABLE `staff` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` longtext COLLATE utf8_unicode_ci,
  `description` longtext COLLATE utf8_unicode_ci,
  `icon` longtext COLLATE utf8_unicode_ci,
  `date` longtext COLLATE utf8_unicode_ci,
  `company` longtext COLLATE utf8_unicode_ci,
  `companyurl` longtext COLLATE utf8_unicode_ci,
  `appurl` longtext COLLATE utf8_unicode_ci,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=5 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci

Here is what is echoed out on the page:

[{"id":"4","name":"Noter 2","description":null,"icon":"http:\/\/images.apple.com\/webapps\/productivity\/images\/noter2_20091223182720-thumb.jpg","date":"1262032317","company":"dBelement, LLC","companyurl":"http:\/\/dbelement.com\/","appurl":"http:\/\/noter2.dbelement.com"},{"id":"3","name":"Noter 2","description":null,"icon":"http:\/\/images.apple.com\/webapps\/productivity\/images\/noter2_20091223182720-thumb.jpg","date":"1262032317","company":"dBelement, LLC","companyurl":"http:\/\/dbelement.com\/","appurl":"http:\/\/noter2.dbelement.com"}]

Any ideas?

Could you provide information on the schema of your "staff" table. Is there a column called description? — mopoke
– mopoke, Commented Dec 28, 2009 at 23:10
all of these fields will echo out if i just simply do an echo of $r['description'] outside of the for() statement? — tarnfeld
– tarnfeld, Commented Dec 28, 2009 at 23:12
Or perhaps some example content from $r['description'] would help. What datatype is it? — mopoke
– mopoke, Commented Dec 28, 2009 at 23:13

ntd · Accepted Answer · 2009-12-29 00:36:50Z

260

I bet you are retrieving data in non-utf8 encoding: try to put mysql_query('SET CHARACTER SET utf8') before your SELECT query.

answered Dec 29, 2009 at 0:36

ntd

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9 Comments

fabio Over a year ago

hi, this answer saved my life, thank you. I was having the same problem here. I had values with non-utf8 chars like "Validação de Formulários". I know this question is a little bit old now, but that's the awesomeness of internet!!

masakielastic Over a year ago

mysql_set_charset is better for the security reason since PHP 5.2.3. See php.net/manual/en/function.mysql-set-charset.php for the details.

ntd Over a year ago

Because UTF8 is the lingua franca on the web. Instead of cluttering the API with additional parameters and overhead, PHP (rigthly) uses the most common encoding, leaving to you the conversion burden if you use an uncommon (or an almost dead, as in your case) encoding.

bejs Over a year ago

The recommended way of doing this has now changed. I tried to edit this answer to include a link but was rejected. The correct way is in my answer below.

ntd Over a year ago

@VeeK it is not enough to have your fields stored in UTF-8: you must configure your server to answer to clients in UTF-8. AFAIK stock mysql and mariadb use latin1.

|

K. Norbert · Accepted Answer · 2013-08-22 12:10:06Z

120

If you have at least PHP 5.5, you can use json_last_error_msg(), which will return a string describing the problem.

If you don't have 5.5, but are on/above 5.3, you can use json_last_error() to see what the problem is.

It will return an integer, that you can use to identify the problem in the function's documentation. Currently (2012.01.19), the identifiers are:

0 = JSON_ERROR_NONE
1 = JSON_ERROR_DEPTH
2 = JSON_ERROR_STATE_MISMATCH
3 = JSON_ERROR_CTRL_CHAR
4 = JSON_ERROR_SYNTAX
5 = JSON_ERROR_UTF8

These can change in future versions, so it's better to consult the manual.

If you are below 5.3, you are out of luck, there is no way to ask what the error was.

edited Aug 22, 2013 at 12:10

answered Dec 29, 2009 at 1:25

K. Norbert

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Comments

Pablo Abdelhay · Accepted Answer · 2013-03-13 14:59:11Z

18

ntd's anwser didn't solve my problem. For those in same situation, here is how I finally handled this error: Just utf8_encode each of your results.

while($row = mysql_fetch_assoc($result)){
    $rows[] = array_map('utf8_encode', $row);
}

Hope it helps!

answered Mar 13, 2013 at 14:59

Pablo Abdelhay

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1 Comment

Paschalis Over a year ago

I had encoding problems too. w/ mixed encoding. solution i found: stackoverflow.com/a/3521396/776345

Hussein Nazzal · Accepted Answer · 2013-06-24 10:36:00Z

10

You should pass utf8 encoded string in json_encode. You can use utf8_encode and array_map() function like below:

<?php
    $encoded_rows = array_map('utf8_encode', $rows);
    echo json_encode($encoded_rows);
?>

edited Jun 24, 2013 at 10:36

Hussein Nazzal

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answered Nov 7, 2012 at 13:56

koder

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Comments

Ivo Urbanek · Accepted Answer · 2013-02-22 18:22:24Z

9

few day ago I have the SAME problem with 1 table.

Firstly try:

echo json_encode($rows);
echo json_last_error();  // returns 5 ?

If last line returns 5, problem is with your data. I know, your tables are in UTF-8, but not entered data. For example the input was in txt file, but created on Win machine with stupid encoding (in my case Win-1250 = CP1250) and this data has been entered into the DB.

Solution? Look for new data (excel, web page), edit source txt file via PSPad (or whatever else), change encoding to UTF-8, delete all rows and now put data from original. Save. Enter into DB.

You can also only change encoding to utf-8 and then change all rows manually (give cols with special chars - desc, ...). Good for slaves...

answered Feb 22, 2013 at 18:22

Ivo Urbanek

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1 Comment

Peter Krauss Over a year ago

or use JSON_PARTIAL_OUTPUT_ON_ERROR option to see the problem (eg. the field with UTF8 will be null).

Community · Accepted Answer · 2020-06-20 09:12:55Z

5

For anyone using PDO, the solution is similar to ntd's answer.

From the PHP PDO::__construct page, as a comment from the user Kiipa at live dot com:

To get UTF-8 charset you can specify that in the DSN.

$link = new PDO("mysql:host=localhost;dbname=DB;charset=UTF8");

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Dec 1, 2016 at 5:44

MichaelS

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Comments

mpen · Accepted Answer · 2009-12-28 23:35:07Z

4

AHHH!!! This looks so wrong it hurts my head. Try something more like this...

<?php
include('db.php');

$result = mysql_query('SELECT `id`, `name`, `description`, `icon` FROM `staff` ORDER BY `id` DESC LIMIT 20') or die(mysql_error());
$rows = array();
while($row = mysql_fetch_assoc($result)){
    $rows[] = $row;
}

echo json_encode($rows);
?>

When iterating over mysql_num_rows you should use < not <=. You should also cache this value (save it to a variable) instead of having it re-count every loop. Who knows what it's doing under the hood... (might be efficient, I'm not really sure)
You don't need to copy out each value explicitly like that... you're just making this harder on yourself. If the query is returning more values than you've listed there, list only the ones you want in your SQL.
mysql_fetch_array returns the values both by key and by int. You not using the indices, so don't fetch em.

If this really is a problem with json_encode, then might I suggest replacing the body of the loop with something like

$rows[] = array_map('htmlentities',$row);

Perhpas there are some special chars in there that are mucking things up...

edited Dec 28, 2009 at 23:35

answered Dec 28, 2009 at 23:19

mpen

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9 Comments

tarnfeld Over a year ago

[{"id":"4","name":"Noter 2","description":null,"icon":"http:\/\/images.apple.com\/webapps\/productivity\/images\/noter2_20091223182720-thumb.jpg","date":"1262032317","company":"dBelement, LLC","companyurl":"http:\/\/dbelement.com\/","appurl":"http:\/\/noter2.dbelement.com"},{"id":"3","name":"Noter 2","description":null,"icon":"http:\/\/images.apple.com\/webapps\/productivity\/images\/noter2_20091223182720-thumb.jpg","date":"1262032317","company":"dBelement, LLC","companyurl":"http:\/\/dbelement.com\/","appurl":"http:\/\/noter2.dbelement.com"}]

mpen Over a year ago

@tarnfield: Well, is that what you want or not? Oh..you've got some additional info in there...here... let me fix that for you.

tarnfeld Over a year ago

yeah "description" returns null

mpen Over a year ago

If the description is returning null then it probably is null. Try echo $row['description'].'<br/>'; in that loop and see what it says.

fabio Over a year ago

hi, this answer saved my life, thank you. I was having the same problem here. I had values with non-utf8 chars like "Validação de Formulários". I know this question is a little bit old now, but that's the awesomeness of internet!!

|

bejs · Accepted Answer · 2014-09-19 04:37:21Z

4

The PHP.net recommended way of setting the charset is now this:

mysqli_set_charset('utf8')

answered Sep 19, 2014 at 4:37

bejs

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Comments

Victor S · Accepted Answer · 2018-09-13 20:08:38Z

1

For me, an issue where json_encode would return null encoding of an entity was because my jsonSerialize implementation fetched entire objects for related entities; I solved the issue by making sure that I fetched the ID of the related/associated entity and called ->toArray() when there were more than one entity associated with the object to be json serialized. Note, I'm speaking about cases where one implements JsonSerializable on entities.

answered Sep 13, 2018 at 20:08

Victor S

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Comments

Jérôme Verstrynge · Accepted Answer · 2011-09-13 19:04:24Z

-4

I had the same problem and the solution was to use my own function instead of json_encode()

echo '["' . implode('","', $row) . '"]';

edited Sep 13, 2011 at 19:04

Jérôme Verstrynge

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answered Jan 31, 2011 at 12:52

Laci

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