construct a complex JSON object from SQL result in PHP - php

Question

I have a db with many tables. One table represents products, one other table represents categories. One product can belong to many categories. So when I request my db to display the products with their categories I of course retrieve many rows as many categories each product has.
For instance the result would be
product_name|category |city
Test1 |cinema |paris
Test1 |entertainment |paris
Test1 |Other |paris
Test2 |Food |new york
Test2 |Restaurant |new york
Test2 |Night |new york
What I am trying to do is to create a JSON object using a PHP script for each product name which looks like this :
[
{
"product_name": "Test1",
"categorie": [
"cinema",
"entertainment",
"Other"
],
"city": "paris"
},
{
"product_name": "Test2",
"categorie": [
"Food",
"Restaurant",
"Night"
],
"city": "new york"
}
]
When I tried to use json_encode but unsuccessfully I got duplicate rows.
thanks for your help

Answer 1

You will need to reorder your data before the json_encode
If $rows is the response of your db, you have to go throw
$data = [];
foreach($rows as $row) {
$name = $row['product_name'];
if(!isset($data[$name])) {
$data[$name] = [
'product_name' => $name,
'city'=>$row['city'],
'categories'=>[]
];
}
$data[$name]['categories'][] = $row['category'];
}
json_encode(array_values($data)); //this is what you want
Thats it!
Maybe you need while ($row=mysqli_fetch_row($result)) instead of foreach, depending on your sql query builder you use. But the idea is the same