PHP-generarted JSON File Errors - php

Question

I am currently using a PHP script to create a cache of JSON files. We have a PHP file on our server that queries a very large database, and returns result sets in JSON format (so we can use it on the site in jQuery and other frameworks).
The script for presenting the raw JSON from our database works great, and I made a simple cache building script that also works to a degree. However, we have noticed some odd things happening with the resulting cache file.
PHP seems to be adding slashes to the quote marks, as well as adding superfluous " to the beginning and end of the JSON.
Here is a sample of the JSON we're passing in (note that it's not complete):
[
{
"id":1580,
"name":"Fydell House",
"address1":"South Square",
"address2":null,
"towncity":"Boston",
"county":"Lincolnshire",
"postcode":"PE21 6HU",
"addressVerbose":"South Square
Boston
Lincolnshire
PE21 6HU
",
"addressVerboseLinked":"",
"longitude":-0.022778,
"latitude":52.975806,
"londonBorough":null,
"telno":"01205 351 520",
"faxno":null,
"email":null,
"webaddress":null,
"mainimg":null,
"venueType":"Historic Building",
"description":null,
"excerpt":" ",
"images":null,
"creationDate":943920000,
"londonfeatured":false,
"unusual":false,
"featured":false,
"active":true,
"trial":false,
"modifiedDate":1234709308,
"hits":"1579",
"allowReviews":false,
"amenities":null,
"imagealt":"Lincolnshire wedding reception venue in Boston, Fydell House",
"imagetitle":"Lincolnshire wedding venues in Boston",
"car_directions":null,
"pub_directions":null,
"additional_info":null,
"listedBy":0,
"listedByName":null,
"region":null
}
]
And the PHP code that outputs the JSON file and stores it on our server:
// Function to output the contents from the live data, and create a cache file:
function create_cache_file($url, $filename)
{
$url = str_replace(' ', '%20', $url);
$json_string = file_get_contents($url);
$file = fopen($filename, 'w');
// If there is a problem creating the file:
if(!$file)
{
die('error creating the file!');
}
else
{
fwrite($file, json_encode($json_string));
fclose($file);
echo $json_string;
}
}
And this is what the file looks like after it's been processed with PHP and stored on our server:
"[{\"id\":437,\"name\":\"Lanteglos Country House Hotel\",\"address1\":\"Lanteglos-by-Camelford\",\"address2\":null,\"towncity\":\"Camelford\",\"county\":\"Cornwall\",\"postcode\":\"PL32 9RF\",\"addressVerbose\":\"Lanteglos-by-Camelford<br \\\/>Camelford<br \\\/>Cornwall<br \\\/>PL32 9RF<br \\\/>\",\"addressVerboseLinked\":\"\",\"longitude\":-4.695491,\"latitude\":50.612462,\"londonBorough\":null,\"telno\":\"01840 213 551\",\"faxno\":null,\"email\":null,\"webaddress\":null,\"mainimg\":null,\"venueType\":\"Hotel\",\"description\":null,\"excerpt\":\" \",\"images\":null,\"creationDate\":943920000,\"londonfeatured\":false,\"unusual\":false,\"featured\":false,\"active\":true,\"trial\":false,\"modifiedDate\":1234662248,\"hits\":\"1145\",\"allowReviews\":false,\"amenities\":null,\"imagealt\":\"Cornwall wedding reception venue in Camelford, Lanteglos Country House Hotel\",\"imagetitle\":\"Cornwall wedding venues in Camelford\",\"car_directions\":null,\"pub_directions\":null,\"additional_info\":null,\"listedBy\":0,\"listedByName\":null,\"region\":null},{\"id\":438,\"name\":\"Rosehill Public House\",\"address1\":\"Little Petherick\",\"address2\":null,\"towncity\":\"Wadebridge\",\"county\":\"Cornwall\",\"postcode\":\"PL27 7QT\",\"addressVerbose\":\"Little Petherick<br \\\/>Wadebridge<br \\\/>Cornwall<br \\\/>PL27 7QT<br \\\/>\",\"addressVerboseLinked\":\"\",\"longitude\":-4.94093,\"latitude\":50.51259,\"londonBorough\":null,\"telno\":\"01841 540 777\",\"faxno\":null,\"email\":null,\"webaddress\":null,\"mainimg\":null,\"venueType\":\"Inn \\\/ Pub\",\"description\":null,\"excerpt\":\" \",\"images\":null,\"creationDate\":943920000,\"londonfeatured\":false,\"unusual\":false,\"featured\":false,\"active\":true,\"trial\":false,\"modifiedDate\":1234752874,\"hits\":\"818\",\"allowReviews\":false,\"amenities\":null,\"imagealt\":\"Cornwall wedding reception venue in Wadebridge, Rosehill Public House\",\"imagetitle\":\"Cornwall wedding venues in Wadebridge\",\"car_directions\":null,\"pub_directions\":null,\"additional_info\":null,\"listedBy\":0,\"listedByName\":null,\"region\":null}]"
This is causing some serious problems elsewhere on the site when we try to decode the JSON. While we can use stripslashes to remove the slashes, some of the other areas are also causing parse errors (that weren't present using the raw data served up by the first PHP file).
Can anyone suggest why PHP is adding slashes and erroneous quote marks around the string? Ideally, we would like a work-around at the point of creating the JSON file on the server, not reading it from it...

Answer 1

I take it that file_get_contents($url) returns you a JSON encoded file? Then your problem is that you're JSON encoding it again. "[{\"id\":437,\"nam... is the proper JSON encoded representation of the string [{"id":1580,"nam....
If you json_decoded it when reading from the cache file, you'd get the original JSON string back. Or just don't json_encode it.