JSON save in Database and load with JQuery - php

Question

I create a huge JSON-Object and save it in my database. But when I load the "string" and echo it in PHP, I can't access the JSON Object in JQuery. Do I have to consider something if I want to save my JSON Object in a MySQL Database (when I just create the Array and then echo it with "echo json_encode($arr);" it works fine, but I need to save the Object for caching).
{"247":{"0":"This is a
question","1":"","2":"247","3":"0","answers":[["Answer1","960","1"],["Answer
2","962","0"],["Answer
3","961","0"],["Answer
4","963","0"]]},{"248":{"0":"This is a
question","1":"","2":"247","3":"0","answers":[["Answer1","960","1"],["Answer
2","962","0"],["Answer
3","961","0"],["Answer
4","963","0"]]}}
just an excerpt
If I just echo this JSON-Object, everything works fine, but if I load the same string from the database and echo it, it doesn't work.
Update 1: forget to tell that I'm using a TEXT-Field with UTF8_general_ci collation
Update 2: Maybe a little bit more code:
function start() {
$(".start").click(function () {
$.post("load_script.php", { }, function(data){
alert(data[247][0]);
}, "json");
return false;
});
}
this loads the script and should alert "This is a question"
<?php
require_once('connect.php');
$ergebnis = mysql_query("SELECT text FROM cache_table ORDER BY RAND() LIMIT 1");
while($row = mysql_fetch_object($ergebnis)) {
$output = $row->text;
}
echo $output;
?>
this is the script, where I load the database entry with the JSON-Object.
Update 3:
I think I solved the problem. Some break sneaked into my JSON-Object so I do this, before the output:
$output = str_replace("\n", "", $output);
$output = str_replace("\r", "", $output);
$output = str_replace("\r\n", "", $output);

Answer 1

I'd suggest looking at what your javascript is seeing. Instead of asking jQuery to interpret the json for you, have a look at the raw data:
function start() {
$(".start").click(function () {
$.post("load_script.php", { }, function(data){
alert(data);
}, "text");
return false;
});
}
For example, if part of the string gets oddly encoded because of the UTF-8, this might cause it to appear.
Once you've done that, if you still can't spot the problem, try this code:
var data1, data2;
function start() {
$(".start").click(function () {
$.post("load_script.php", {src: "db" }, function(data){
data1 = data;
}, "text");
$.post("load_script.php", {src: "echo" }, function(data){
data2 = data;
}, "text");
if (data1 == data2) {
alert("data1 == data2");
}
else {
var len = data1.length < data2.length ? data1.length : data2.length;
for(i=0; i<len; ++i) {
if (data1.charAt(i) != data2.charAt(i)) {
alert("data1 first differs from data2 at character index " + i);
break;
}
}
}
return false;
});
}
And then change the PHP code to either return the data from the database or simply echo it, depending on the post parameters:
<?php
if ($_POST['src'] == 'db')) {
require_once('connect.php');
$ergebnis = mysql_query("SELECT text FROM cache_table ORDER BY RAND() LIMIT 1");
while($row = mysql_fetch_object($ergebnis)) {
$output = $row->text;
}
}
else {
$output = '{"247":{"0":"This is a question","1":"","2":"247","3":"0","answers":[["Answer1","960","1"],["Answer 2","962","0"],["Answer 3","961","0"],["Answer 4","963","0"]]},{"248":{"0":"This is a question","1":"","2":"247","3":"0","answers":[["Answer1","960","1"],["Answer 2","962","0"],["Answer 3","961","0"],["Answer 4","963","0"]]}}';
}
echo $output;
?>
Hope that helps!

Answer 2

I got this to work in a slightly different manner. I've tried to illustrate how this was done.
In Plain English:
use urldecode()
In Commented Code Fragments
$json = $this->getContent($url); // CURL function to get JSON from service
$result = json_decode($json, true); // $result is now an associative array
...
$insert = "INSERT INTO mytable (url, data) ";
$insert .= "VALUES('" . $url . "', '" . urlencode(json_encode($result)) . "') ";
$insert .= "ON DUPLICATE KEY UPDATE url=url";
...
/*
** Figure out when you want to check cache, and then it goes something like this
*/
$sqlSelect = "SELECT * FROM mytable WHERE url='" . $url . "' LIMIT 0,1";
$result = mysql_query($sqlSelect) or die(mysql_error());
$num = mysql_numrows($result);
if ($num>0) {
$row = mysql_fetch_assoc($result);
$cache = json_decode(urldecode($row['data']), true);
}
Hope this is helpful

Answer 3

Maybe you use varchar field and your string just doesn't fit in 255 chars?