Develop Reference

How to interpret extended json data

Description of the problem
I will not write any codes as much of my problem is something linked with the knowledge to interpret some data. I am doing a project and had to use a nonsql database to store data the sampled information from a microcontroller. The chosen db was mondodb. I wrote all the code that stores the info and now i want to exhibit the date on a html page. The problem is that when i do the request using restapi to the mongodb, the json that was stored there comes in the extened json format, i.e.:
"_id": {
"$oid": "6230d05dcf81542c5aabc30b"
},
"sensor": {
"$numberDouble": "1"
}
But it should have come as the data is stored in the db:
"{
_id": "6230d05dcf81542c5aabc30b",
"sensor": 1.0
}
As you can see, the the json comes with extra information linked to the type of the variable that is stored. But i don't really know how to use that information in javascript. I would just read it for example as json.sensor.$numberDouble if i wanted to get the information about the sensor instead of json.sensor if the json was in the normal way. I don't see much of an use to the extended version. Is something i am doing wrong?

Make sure, that you Parse API response, like-
response.json()

It looks like you're getting back an EJSON response. If you want to send back standard JSON response then that should be set as the Content-Type on the server response.
function(req, res) {
data = { ... }; // Your data here
res.setHeader("Content-Type", "application/json");
res.setBody(JSON.stringify(data));
}
If you don't have control over the server side, then convert the EJSON back to plain JSON using the meteor EJSON library.

Is it risky to parse JSON string from websockets?

I'm writing an Angular2 web application, and I want bidirectional communication with the server, so the perfect solution is with websockets.
Mozilla fundation teaches to use JSON.stringify(msg) to parse a string that represents a JSON message, both for sending and receiving data with websocket. This leads to some thoughts on injection. For example, suppose the following JSON document being transfered from the server to the client's machine:
{
message{
from: "paul",
text:"hello!",
date:"01/01/2017"
}
}
Now suppose paul changes his name to "paul\" and sends the following text:
,text: alert('xss'),something:"
then the following JSON received by the client would be:
{
message{
from: "paul\",
text:",text: alert('xss'),something:"",
date:"01/01/2017"
}
}
which is, in fact, the following JSON (just rearranged):
{
message{
from: "paul\",text:",
text: alert('xss'),
something:"",
date:"01/01/2017"
}
}
which could cause problems, depending on what is done with this JSON, I guess. Is there some way to prevent these things, or is the JSON.stringfy technique safe because when inserting data from the JSON into the DOM, the text attribute would be undefined because alert('xss') is not a string (or does not return anything)?
Also, see that if there's no problem with calling a function like alert(), we were able to set the something variable to anything we wanted, this is for sure risky.

How to retrieve data from DB and turn them to object in my case?

I am using postgres row_to_json function to get the data that were stored through JSON.stringify(). However, when I retrieve it and do JSON.parse(), it gave me "unexpected token ," error message.
My original data from frontend:
{
"company":[
{"name":"test company"},
{"ceo":"John"}
]
}
I do JSON.stringify(myData.company) and store it to postgres.
When I retrieve it, I have row_to_json function to get the data.
and the console.log(myRetrieveData) become
{"{\"name\":\"test company\"}","{\"ceo\":\"John\"}"}
I used JSON.parse(myRetrieveData) and got 'unpexted token ,' error.
I understand row_to_json turn it into json and can't be used on JSON.parse but the function is needed for my other data.
I am not sure how to fix this. Can anyone help me about it?
Thanks a lot!

Looks like the JSON that you retrieved from the query is not of the proper format for it to be parsed. Inorder to avoid this please make sure that the JSON being stored into the DB is of proper JSON format, so that it parsed.If this is not achievable the response obtained from the db has to be modified to proper JSON. With the above data it can be done as follows.
var improperJson = '{"{\"name\":\"test company\"}","{\"ceo\":\"John\"}"}';
var properJson = improperJson.replace(/","/g, ",").replace(/^{"/, "[").replace(/"}$/, "]");
console.log(JSON.parse(properJson));//should give you the parsed JSON

Converting PHP object to JSON object using only Javascript

I am making a mobile app with Phonegap and using Wordpress as a backend. I am using Advanced Custom Fields with a Google Maps post field which returns a PHP object to the app using JSON API. My Wordpress backend sends a normal JSON object to the app, but inside that object is where a stringified PHP object is returned.
I need to convert the PHP object to a JSON object somehow on the client side(the app which is not in Wordpress). I have looked at other answers that say to use json_encode for this but my problem is that the app is just HTML/Javascript and no PHP. Is there a way to use PHP code in the middle of a Javascript function to do this? Or would it be better to change the backend so that it returns a JSON object instead of a PHP object in the first place? If so, how do I do that?
My experience in PHP is still somewhat limited so any help is appreciated.
edit: To clarify a bit more, I am using Wordpress on a separate domain from my Phonegap app and only using the JSON API plugin on the Wordpress end. I am then using jQuery Ajax calls to retrieve data from the Wordpress backend.
Also the returned PHP object looks like this: a:3:{s:7:\"address\";s:48:\"8915 W 159th St, Orland Hills, IL, United States\";s:3:\"lat\";s:17:\"41.60111599999999\";s:3:\"lng\";s:11:\"-87.8364575\";}
Another way I just thought of as well, would it be possible to just leave it as a PHP object and still read out the values from it somehow? I don't NEED it to be a JSON array, I just need a way to read the individual elements in the array in one way or another.
Here is also a tiny snippet of the JSON returned to clarify what I'm talking about.
"custom_fields": {
"location": [
"a:3:{s:7:\"address\";s:48:\"8915 W 159th St, Orland Hills, IL, United States\";s:3:\"lat\";s:17:\"41.60111599999999\";s:3:\"lng\";s:11:\"-87.8364575\";}"
]
}
That of course isn't the entire JSON object but it gives you an idea of what I'm dealing with.

I know you have a solution that works on the front end, but I still think it'd be better to fix this on the server.
Based on our conversation in the comments, I've had a closer look the code in the WordPress forum. The problem seems to be that the location field is an array of strings, not just a string. maybe_unserialize (and is_serialized, which it uses) don't handle arrays. Here's the updated code, which you should be able to drop into your theme's functions.php. I did a quick test, and it works for me.
class unserialize_php_arrays_before_sending_json {
function __construct() {
add_action( 'json_api_import_wp_post',
array( $this, 'json_api_import_wp_post' ),
10,
2 );
}
function json_api_import_wp_post( $JSON_API_Post, $wp_post ) {
foreach ( $JSON_API_Post->custom_fields as $key => $custom_field ) {
if (is_array($custom_field)) {
$unserialized_array = array();
foreach($custom_field as $field_key => $field_value) {
$unserialized_array[$field_key] = maybe_unserialize( $field_value );
}
$JSON_API_Post->custom_fields->$key = $unserialized_array;
}
else {
$JSON_API_Post->custom_fields->$key = maybe_unserialize( $custom_field );
}
}
}
}
new unserialize_php_arrays_before_sending_json();

If you're using a JSON API to retrieve the data, then why don't you deliver the data in JSON format to your app? Otherwise you seem to remove much of the point of using an API in the first place... You could of course parse that string in JavaScript if you really want to but that's a very ugly and error prone solution.
The JSON API plugin does seem to use JSON:
https://wordpress.org/plugins/json-api/screenshots/

I need to convert the PHP object to a JSON object somehow on the client side(the app which is not in Wordpress).
This bit here leaves me confused. You do not have PHP objects on the client-side, PHP is a back-end technology. What is returned to the client is a string which can be HTML, XML, JSON, plaintext on any other form of encoding.
That said, saying you have an object $obj in PHP, you could pass it to your front-end application creating an end-point retrieve_object.php and in there:
echo json_encode($obj);
So long as that is the only thing your are outputting, you lient-side app can make a request (Eg: AJAX) to retrieve_object.php and get the json object.
BUT , and this is important (!) in doing so you serialize object properties. You will lose any PHP object method. If any object property is an object itself (EG: A DB Connection) then this will be lost too.
Hope this helps!

How to separate JSON data from ArrayBuffer receiving from websocket

I tried unsuccessful to separate JSON data from an array of buffer receiving from websocket which look like this.
{"type":"string","data":{"UklGRkIjAABXRUJQVlA4IDYjAACQswCdASqrAfAAPm0wlUemI"}}
[object ArrayBuffer]
the objective is to read them separately with proper function. My old method is parse the JSON first. If fail, pass through another function.
The reason I send them in both formats is that converting JSON data to an array or array to JSON would increase file size around three fold.
The best practice is to send them separately.
However, at the terminal I read JSON data with
var json = JSON.parse(e.data);
and read the ArrayBuffer with DataView method.
The app works properly on the surface, but if you check at console.log there are too many Uncaugth Error.
It also blocks data flow at one point, causing the stream overflow not very smooth.
Thanks for any suggestions in advance.

Got it:
if ((typeof data == 'object')) {
// this would return ArrayBuffer
} else {
// this would return JSON
}