How to reproduce with PHP a particular JSON document - php

Question

I have been trying to solve my problem for days, but without getting the desidred result. Here's a particular structure for a JSON file:
{
"detections": {
"timestamp": "12/04/2016/ 20:25:00",
"rooms": [
{
"name": "r1",
"sensors": [
{
"id": 10,
"type": "rad",
"value": 100,
"valMax": 600,
"valMin": 100
},
{
"id": 12,
"type": "temp",
"value": 30.5,
"valMax": 1000,
"valMin": 0
}
]
},
{
"name": "r2",
"sensors": [
{
"id": 20,
"type": "temp",
"value": 20.7,
"valMax": 1000,
"valMin": 0
},
{
"id": 15,
"type": "rad",
"value": 800,
"valMax": 600,
"valMin": 100
}
]
}
]
}
}
I must encode with that structure data that I've retrieved from MySQL Database.
It consists of three tables linked with foreign key constraints. Now, the code I've written for this is the following:
while($row = mysqli_fetch_array($result)) {
array_push($detections, array("timestamp"=>$row['timestamp'],
"rooms"=>array("name"=>$row['name'],
"sensors"=>array("id"=>$row['id'], "type"=>$row['type'], "value"=>$row['value'], "valMin"=>$row['valMin'],
"valMax"=>$row['valMax']))
));
}
But it gives me this result:
{
"detections": [{
"timestamp": "2016-09-10 17:59:06",
"rooms": {
"name": "Stanza dei Giochi",
"sensors": {
"id": "1",
"type": "prova2",
"value": "12",
"valMin": "1",
"valMax": "12"
}
}
}, {
"timestamp": "2016-09-11 00:41:21",
"rooms": {
"name": "Stanza dei Giochi",
"sensors": {
"id": "1",
"type": "prova2",
"value": "21",
"valMin": "1",
"valMax": "12"
}
}
}, {
"timestamp": "2016-09-10 19:59:20",
"rooms": {
"name": "Stanza dei Giochi",
"sensors": {
"id": "3",
"type": "prova",
"value": "13",
"valMin": "11",
"valMax": "13"
}
}
}, {
"timestamp": "2016-09-11 00:41:21",
"rooms": {
"name": "Stanza dei Giochi",
"sensors": {
"id": "3",
"type": "prova",
"value": "23.5",
"valMin": "11",
"valMax": "13"
}
}
}]
}
which is similar but not the same :/
As I've noticed from the JSON structure I would get, detections with the same timestamp but with different rooms, sensors and values are collected together... but I don't know how to realize that.
Hope y'all can give me a hand, thanks >.<

Answer 1

You are building your array wrong to achieve that structure.
To achieve the desired structure your array needs to look like this
<?php
array (
'detections' =>
array (
'timestamp' => '12/04/2016/ 20:25:00',
'rooms' =>
array (
0 =>
array (
'name' => 'r1',
'sensors' =>
array (
0 =>
array (
'id' => 10,
'type' => 'rad',
'value' => 100,
'valMax' => 600,
'valMin' => 100,
),
1 =>
array (
'id' => 12,
'type' => 'temp',
'value' => 30.5,
'valMax' => 1000,
'valMin' => 0,
),
),
),
1 =>
array (
'name' => 'r2',
'sensors' =>
array (
0 =>
array (
'id' => 20,
'type' => 'temp',
'value' => 20.699999999999999,
'valMax' => 1000,
'valMin' => 0,
),
1 =>
array (
'id' => 15,
'type' => 'rad',
'value' => 800,
'valMax' => 600,
'valMin' => 100,
),
),
),
),
),
);
Check also check json_decode and json_encode