how to pass JSON data to php using ajax post - php

Question

Here is the code: (the #debug div text is shown below)
$("#debug").text(JSON.stringify(data));
// Try to save to a file
$.ajax({
type: 'POST',
url: './json.php',
dataType: 'json',
data: JSON.stringify(data),
success: function(xhr, status, errorMessage) {
if( xhr.responseText == "Success" ) {
alert("Success!");
} else {
alert("response was "+xhr.responseText);
}
},
error: function(xhr, status, errorMessage) {
$("#debug").append("RESPONSE: "+xhr.responseText+", error: "+errorMessage);
}
});
The JSON.php page is:
<?php
openlog("scriptLog.txt", LOG_PID | LOG_PERROR, LOG_LOCAL0);
$json = $_POST['json'];
// open syslog, include the process ID and also send
// the log to standard error, and use a user defined
// logging mechanism
syslog(LOG_DEBUG, "Received Data");
if (json_decode($json) != null) { /* sanity check */
$file = fopen('./data.json','w+');
fwrite($file, json_decode($json));
fclose($file);
} else {
syslog(LOG_DEBUG,"Failure");
return "Failure, json decode is null";
}
closelog();
return "Success";
?>
In the log I get:
Mar 14 14:50:54 scriptLog.txt[21902] : Received Data
Mar 14 14:50:54 scriptLog.txt[21902] : Failure
In the debug div text I get:
{"1457981454959":{"id":1457981454959,"code":"1","title":"Test","date":"22/03/2016","description":"a Task"}}RESPONSE: , error: SyntaxError: JSON Parse error: Unexpected EOF
1) How can I examine the posted data? I.e. "Received Data: "+WHAT in syslog to see its structure.
2) JSON parse error? Most examples I see use this stringify function. then they use json_decode to get the values. Why the parse error?

Answer 1

1) How can I examine the posted data? I.e. "Received Data: "+WHAT in syslog to see its structure.
As I understand you are debugging the code, so syslog can be not the best idea.
I would simply use the browser network console to see the content of requests and a simple php file like this to see the content of $_POST:
<?php
echo json_encode($_POST);
In more complex cases - use the actual debugger.
2) JSON parse error? Most examples I see use this stringify function. then they use json_decode to get the values. Why the parse error?
You are trying to use the json key in your $_POST, but you didn't instruct jQuery to add it, so you are receiving not what you expected.
There are few issues with your $.ajax call, here is the commented version:
$.ajax({
type: 'POST',
url: './json.php',
dataType: 'json', // Note: dataType is only important for the response
// jQuery now expects that your server code
// will return json
// here you need to add the 'json' key
data: {'json': JSON.stringify(data)},
// the success method has different order of parameters
//success: function(xhr, status, errorMessage) {
success: function(data, status, xhr) {
alert("response was "+data);
},
error: function(xhr, status, errorMessage) {
$("#debug").append("RESPONSE: "+xhr.responseText+", error: "+errorMessage);
}
});
Now on the server you will have $_POST['json'] with serialized string and you can json_decode it.
Alternatively you can send the JSON data without serialization:
var data = {'test': 'abc'};
$.ajax({
type: 'POST',
url: './json.php',
// No 'JSON.stringify()', just send your data
data: data,
...
});
And on the server you will have $_POST['test'] with abc value (so you have your json already converted into array).