Why is json_encode adding backslashes? - php

Question

I've been using json_encode for a long time, and I've not had any problems so far.
Now I'm working with a upload script and I try to return some JSON data after file upload.
I have the following code:
print_r($result); // <-- This is an associative array
echo json_encode($result); // <-- this returns valid JSON
This gives me the following results:
// print_r result
Array
(
[logo_url] => http://mysite.com/uploads/gallery/7f/3b/f65ab8165d_logo.jpeg
[img_id] => 54
[feedback] => Array
(
[message] => File uploaded
[success] => 1
)
)
// Echo result
{"logo_url":"http:\/\/mysite.com\/uploads\/gallery\/7f\/3b\/f65ab8165d_logo.jpeg","img_id":"54","feedback":{"message":"File uploaded","success":true}}
Can anyone tell me why json_encode adds slashes?
update
#Quentin said that something is happening between json_encode and .parseJSON and he's right.
Doing a alert(data.toSource()); gives me the dollowing result:
({response:"{\"logo_url\":\"http:\\/\\/storelocator.com\\/wp-content\\/uploads\\/gallery\\/7f\\/3b\\/71b9520cfc91a90afbdbbfc9d2b2239b_logo.jpeg\",\"img_id\":\"62\",\"feedback\":{\"message\":\"File uploaded\",\"success\":true}}", status:200})
And this is not valid JSON. It also adds the status:200 and I have no idea where this comes from.
Could it be that the Plupload bind does something to my returned data?
This is my js script:
uploader.bind('FileUploaded', function(up, file, data) {
alert(data.toSource());
$('#' + file.id + " b").html("100%");
});

Answer 1

Just use the "JSON_UNESCAPED_SLASHES" Option (added after version 5.4).
json_encode($array,JSON_UNESCAPED_SLASHES);

Answer 2

I just came across this issue in some of my scripts too, and it seemed to be happening because I was applying json_encode to an array wrapped inside another array which was also json encoded. It's easy to do if you have multiple foreach loops in a script that creates the data. Always apply json_encode at the end.
Here is what was happening. If you do:
$data[] = json_encode(['test' => 'one', 'test' => '2']);
$data[] = json_encode(['test' => 'two', 'test' => 'four']);
echo json_encode($data);
The result is:
["{\"test\":\"2\"}","{\"test\":\"four\"}"]
So, what you actually need to do is:
$data[] = ['test' => 'one', 'test' => '2'];
$data[] = ['test' => 'two', 'test' => 'four'];
echo json_encode($data);
And this will return
[{"test":"2"},{"test":"four"}]

Answer 3

Can anyone tell me why json_encode adds slashes?
Forward slash characters can cause issues (when preceded by a < it triggers the SGML rules for "end of script element") when embedded in an HTML script element. They are escaped as a precaution.
Because when I try do use jQuery.parseJSON(response); in my js script, it returns null. So my guess it has something to do with the slashes.
It doesn't. In JSON "/" and "\/" are equivalent.
The JSON you list in the question is valid (you can test it with jsonlint). Your problem is likely to do with what happens to it between json_encode and parseJSON.

Answer 4

This happens because the JSON format uses ""(Quotes) and anything in between these quotes is useful information (either key or the data).
Suppose your data was : He said "This is how it is done".
Then the actual data should look like "He said \"This is how it is done\".".
This ensures that the \" is treated as "(Quotation mark) and not as JSON formatting. This is called escape character.
This usually happens when one tries to encode an already JSON encoded data, which is a common way I have seen this happen.
Try this
$arr = ['This is a sample','This is also a "sample"'];
echo json_encode($arr);
OUTPUT:
["This is a sample","This is also a \"sample\""]

Answer 5

Make sure your php script has the right header or it will add the slashes
header('Content-Type: application/json');

Answer 6

I had a very similar problem, I had an array ready to be posted. in my post function I had this:
json = JSON.stringfy(json);
the detail here is that I'm using blade inside laravel to build a three view form, so I can go back and forward, I have in between every back and forward button validations and when I go back in the form without reloading the page my json get filled by backslashes. I console.log(json) in every validation and realized that the json was treated as a string instead of an object.
In conclution i shouldn't have assinged json = JSON.stringfy(json) instead i assigned it to another variable.
var aux = JSON.stringfy(json);
This way i keep json as an object, and not a string.

Answer 7

json_encode will always add slashes.
Check some examples on the manual HERE
This is because if there are some characters which needs to escaped then they will create problem.
To use the json please Parse your json to ensure that the slashes are removed
Well whether or not you remove slashesthe json will be parsed without any problem by eval.
<?php
$array = array('url'=>'http://mysite.com/uploads/gallery/7f/3b/f65ab8165d_logo.jpeg','id'=>54);
?>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
<script type="text/javascript">
var x = jQuery.parseJSON('<?php echo json_encode($array);?>');
alert(x);
</script>
This is my code and i m able to parse the JSON.
Check your code May be you are missing something while parsing the JSON