json_encode to produce complex output - php

Question

Up until now I have just used PHP's json_encode() on simple rows of data, for example
{
"name":"bob",
"age":"22"
}
However I have the need to return JSON which has arrays.
Example output is
{
"success":true,
"payload":
{
"venuedata":
{
"id":"1",
"name":"venue name"
},
"menus": [
{"menuid":"1","menuname":"food","items": [{"item":"pizza","cost":"$12.50"},{"item":"burger","cost":"$14.50"}]},
{"menuid":"2","menuname":"drinks","items": [{"item":"pint of beer","cost":"$5.50"}]}
]
}
}
Now, the venuedata object will come from one PDO query, and the menus will come from another query and the items for each menu will come from another query.
How can I use json_encode to return the example JSON?

Answer 1

A generalized example assuming the menu items and the menus are connected to each other with a foreign key.
Create an array of menus and add for every menu element in the array the menu items.
$arrMenus = array();
$menus = getMenusFromDB();
foreach($menus as $menu) {
$menuItems = getMenuItemsFromDB($menu["id"]);
$arrMenuItems = array();
foreach($menuItems as $menuItem){
$arrMenuItems []= array(
"item" => $menuItem["item"],
"cost" => $menuItem["cost"]
);
}
$arrMenus []= array(
"menuid" => $menu["id"],
"menuname" => $menu["menuname"],
"items" => $arrMenuItems
);
}
Then create an array with the rest of the information and add the "menus" array as part of the "payload" array:
$obj = array(
"success" => true,
"payload" => array(
"venuedata" => array(
"id" => "2",
"name" => "venue name"
),
"menus" => $arrMenus
)
)
After convert the array via json_encode():
$json = json_encode($obj);