Generate nested JSON from SQL using PHP - php

Question

I'm trying to generate a JSON API using PHP to be used as remote server interface for my Android application database.
I managed to generate JSON like this:
{
products: [
{
product_name: "Samsung",
product_category: "phones",
shop_name: "Gadget Store",
user_id: "1",
price: "1999",
date: "2015-04-05",
time: "11:14:44"
},
{
product_name: "Samsung",
product_category: "phones",
shop_name: "IT Store",
user_id: "1",
price: "1899",
date: "2015-04-01",
time: "13:00:00"
},
{
product_name: "Motorola",
product_category: "phones",
shop_name: "IT Store",
user_id: "1",
price: "1499",
date: "2015-04-02",
time: "10:31:29"
}
]
}
But I guess I need a nested JSON which is something like this:
{
products: [
{
product_name: "Samsung",
product_category: "phones",
shops: [
{
shop_name: "Gadget Store",
user_id: "1",
price: "1999",
date: "2015-04-05",
time: "11:14:44"
},
{
shop_name: "IT Store",
user_id: "1",
price: "1899",
date: "2015-04-01",
time: "13:00:00"
}
],
},
{
product_name: "Motorola",
product_category: "phones",
shops: [
shop_name: "IT Store",,
user_id: "1",
price: "199",
date: "2015-04-02",,
time: "10:31:29"
],
}
]
}
How can I achive this result?
The sql query is from 3 different table.
Below is my current code:
class productDB
{
public $product_name = "";
public $product_category = "";
public $shop_name = "";
public $user_id = "";
public $price;
public $date = "";
public $time = "";
function __construct($product_name, $product_category, $shop_name, $user_id, $price, $date, $time)
{
$this->product_name = $product_name;
$this->product_category = $product_category;
$this->shop_name = $shop_name;
$this->user_id = $user_id;
$this->price = $price;
$this->date = $date;
$this->time = $time;
}
class Shop
{
public $shop_name = "";
public $user_id = "";
public $price;
public $date = "";
public $time = "";
function __construct($shop_name, $user_id, $price, $date, $time)
{
$this->shop_name = $shop_name;
$this->user_id = $user_id;
$this->price = $price;
$this->date = $date;
$this->time = $time;
}
}
class product
{
public $product_name = "";
public $product_category = "";
public $shop = "";
function __construct($product_name, $product_category, $shop_name, $user_id, $price, $date, $time)
{
$this->product_name = $product_name;
$this->product_category = $product_category;
$this->shop = new Shop($shop_name, $user_id, $price, $date, $time);
}
}
$query = "SELECT a.product_name, a.product_category,
b.shop_name,
c.user_user_id, c.price, c.date, c.time
FROM price c, item a, shop b
WHERE c.product_product_id = a.product_id AND c.shop_shop_id = b.shop_id";
$product_array = array();
if ($result = $dbc->query($query)) {
while ($obj = $result->fetch_object()) {
$temp_product[] = new ProductDB(
$obj->product_name,
$obj->product_category,
$obj->shop_name,
$obj->user_id,
$obj->price,
$obj->date,
$obj->time);
$product_array = $temp_product;
}
//Give a name to the array
$array_name = 'products';
$product_array = (array($array_name=>$product_array));
$product_object = json_encode($product_array);
echo $product_object;

Answer 1

Here you have a solution which does not require subqueries.
It looks like at least in this example you do not need the ProductDB so we will use directly Product class
To keep the shops in the Product object we need the holder there. We will change $shop into $shops which will hold an array with Shop objects.
Product class:
class Product
{
public $product_name = "";
public $product_category = "";
public $shops = null;
function __construct($product_name, $product_category, $shop_name, $user_id, $price, $date, $time)
{
$this->product_name = $product_name;
$this->product_category = $product_category;
$this->shops = array(new Shop($shop_name, $user_id, $price, $date, $time));
}
public function addShop($shop_name, $user_id, $price, $date, $time)
{
// because $shops is a public property we can check if it still is an array
if (!is_array($this->shops)) {
$this->shops = array();
}
$this->shops[] = new Shop($shop_name, $user_id, $price, $date, $time);
}
}
Ass you can see there is a new function which adds new shops to the array.
Now the part which will group the shops into the products.
$product_array = array();
$currProduct = null;
if ($result = $dbc->query($query)) {
while ($obj = $result->fetch_object()) {
// check if it is a first product or if we have encountered product with different name or category
if ($currProduct === null
|| $currProduct->product_name !== $obj->product_name
|| $currProduct->product_category !== $obj->product_category) {
// create new Product with one position in the shops array
$product = new Product(
$obj->product_name,
$obj->product_category,
$obj->shop_name,
$obj->user_id,
$obj->price,
$obj->date,
$obj->time);
$product_array[] = $product;
// set created product as a currently used
$currProduct = $product;
} else {
// if name and category is the same add shop data to the current product
$currProduct->addShop(
$obj->shop_name,
$obj->user_id,
$obj->price,
$obj->date,
$obj->time);
}
}
$product_array = array('products' => $product_array);
$product_json = json_encode($product_array);
echo $product_json;
}
TO group the data properly it is necessary to sort the products data. So add at the end of the query ORDER BY a.product_name, a.product_category.
That's it :) Let me know how if it worked (if you will use it)
Also if you would like to declare the class properties private and still use json_encode to get the JSON representation of your classes, you can use JsonSerializable interface.
Shop class
class Shop implements \JsonSerializable
{
private $shop_name = "";
private $user_id = "";
private $price;
private $date = "";
private $time = "";
function __construct($shop_name, $user_id, $price, $date, $time)
{
$this->shop_name = $shop_name;
$this->user_id = $user_id;
$this->price = $price;
$this->date = $date;
$this->time = $time;
}
public function JsonSerialize()
{
return get_object_vars($this);
}
}
Product class
class Product implements \JsonSerializable
{
private $product_name = "";
private $product_category = "";
private $shops = null;
function __construct($product_name, $product_category, $shop_name, $user_id, $price, $date, $time)
{
$this->product_name = $product_name;
$this->product_category = $product_category;
$this->shops = array(new Shop($shop_name, $user_id, $price, $date, $time));
}
public function addShop($shop_name, $user_id, $price, $date, $time)
{
$this->shops[] = new Shop($shop_name, $user_id, $price, $date, $time);
}
function getName()
{
return $this->product_name;
}
function getCategory()
{
return $this->product_category;
}
public function JsonSerialize()
{
return get_object_vars($this);
}
}
Main code
[...]
if ($currProduct === null
|| $currProduct->getName() !== $obj->product_name
|| $currProduct->getCategory() !== $obj->product_category) {
[...]
Have fun :)

Answer 2

To keep a consistent JSON structure, the second part would look like this:
{
product_name: "Motorola",
product_category: "phones",
shops: [
shop_name: "IT Store",
user_id: "1",
price: "1499",
date: "2015-04-02",
time: "10:31:29"
]
}
How about something like this:
$queryStr_products = "Select * FROM item";
$queryStr_price = "Select b.shop_name, c.user_user_id, c.price, c.date, c.time FROM price c, shop b WHERE b.shop_id = c.product_product_id and c.product_product_id =";
$product_array = array();
if ($result = $dbc->query($queryStr_products)) {
//Iterate over all products returned
while ($obj = $result->fetch_object()) {
$product_array[] = array (
'product_name' => $obj->product_name,
'product_category' => $obj->product_category,
'shops' => getPricesForProducts($obj->product_id)
);
}
$result->close();
}
echo json_encode(array('products'=>$product_array));
/**
* For clarity purposes
* This returns an array of all product prices for a particular productID
*/
function getPricesForProducts ($productID) {
//You may need to get a new DB connection
if ($result = $dbc2->query($queryStr_price.$productID)) {
$price_array = array();
while($obj = $result->fetch_object()) {
$price_array[] = array (
'shop_name' => $obj->b.shop_name,
'user_id' => $obj->c.user_user.id,
'price' => $obj->c.price,
'date' => $obj->c.date,
'time' => $obj->c.time,
);
}
$result->close();
return $price_array;
} else {
//Maybe you want to set shop_name to "No Prices Found" and user_id = 0;
return array();
}
}