PHP JSON object nested loop data syntax - php

Question

I'm trying to loop through some JSON data and pull out specific values. Here is the JSON data and the partially working code.
$jsondata = '
[
{
"id" : "421356",
"trip_update" : {
"trip" : {
"trip_id" : "421356",
"start_time" : "12:05:00",
"start_date" : "20130926",
"route_id" : "15"
},
"stop_time_update" : {
"stop_sequence" :70,
"departure" : {
"delay" : 240,
"time" : 1380215057
},
"stop_id" : "6090"
},
"stop_time_update" : {
"stop_sequence" :71,
"departure" : {
"delay" : 240,
"time" : 1380215075
},
"stop_id" : "6095"
}
}
}]';
$result = json_decode($jsondata);
foreach($result as $value) {
echo "trip_id: ".$value->trip_update->trip->trip_id;
if (gettype($value->trip_update ) == "object") {
foreach($value->trip_update as $item) {
echo " - stop_sequence: ".$item->stop_sequence;
}
}
}
I can get the first level of data under 'trip_update->trip'. But there can be any number of 'stop_time_update' data within 'trip_update' as well. Since this data relates to the trip_update data, I need to loop through it and correlate it.
The end goal is to save this data to a database (not shown in the code), so for clarity, this would be the simplified 2 rows of DB data I would like to save in this example:
trip_id,stop_sequence
421356,70
421356,71
There can be any number of stop_sequences in the source data.
Here is an interactive link to the code for you to edit or mess with:
http://sandbox.onlinephpfunctions.com/code/f21ca8928da7de3e9fb351edb075d0a446906937

Answer 1

You might get better results if you write your own parser or use a stream-parser with callbacks. Here's a PHP implementation of such a parser that works with callbacks. So instead of reading the whole JSON data into memory, the parser will read the data in chunks and notify your "listener-class" whenever a new object starts or a property was read in etc. By doing this, you should get separate callback events for each stop_time_update property instead of just one value in the parsed array.
Very similar to what SAX is for XML.

Answer 2

Hi maybe you can change the name.
function next_update($coincidencias){
$replace=$coincidencias[0].$GLOBALS["json_stop_time_update"]++;
return $replace;
}
$result= preg_replace_callback("/stop_time_update/","next_update",$jsondata);
$result = json_decode($result);

Answer 3

You should rework your JSON - you have multiple keys with the same name, try to do print_r($result) to see what I am talking about - PHP will override the "stop_time_update" key time after time and you will be able to access only the last entry. Instead, you should organize your JSON like that:
[
{
"id" : "421356",
"trip_update" : {
"trip" : {
"trip_id" : "421356",
"start_time" : "12:05:00",
"start_date" : "20130926",
"route_id" : "15"
},
"stop_time_update" : [{
"stop_sequence" :70,
"departure" : {
"delay" : 240,
"time" : 1380215057
},
"stop_id" : "6090"
}, {
"stop_sequence" :71,
"departure" : {
"delay" : 240,
"time" : 1380215075
},
"stop_id" : "6095"
}]
}
}]
then you will be able to iterate through your data like this:
foreach($result[0]->trip_update->stop_time_update as $update)
{
$time = $update->departure->time;
...
}
If you cannot change the data structure, then what probably could help you is a PULL parser - one that does not return parsed data structure, but allows you to use a data stream instead - this way you could iterate over each node. The only one I managed to find is an extension to PHP:
https://github.com/shevron/ext-jsonreader
Check the usage section.

Answer 4

This JSON response is invalid because it contains duplicate keys but JSON doesn't allow duplicate keys.
You should contact the service you're trying to request this response from.
If you have a valid JSON response then you can decode it using the json_decode function which returns an object or an array (depends on the second parameter);
You cannot use a JSON parser for this as it will always overwrite the first element due to the same keys. The only proper solution would be asking whoever creates that "JSON" to fix his code to either use an array or an object with unique keys.
Another option is to write your own decoder function for parse it