mongodb gathering all records from different collections - php

Question

i am trying to grab all records from mongodb using php.
i have two collections. question is, in practice will i be able to make a simple sentence such as for each record on the database? :
ie: john[from names collection] lives in city[from city collection] who
drives[from car collection].
Is this the correct coding for the above? I am still a newbie trying to learn step by step
<?php foreach ($details as $doc) {
echo $doc['name'] . ' lives in'; }
foreach ($place as $city) {
echo $city['name'] . ' who drives a '; }
foreach ($car as $ride) {
echo $ride['name'];
echo '<br>'} ?>
your thoughts are welcome

Answer 1

I expect this to be used with, say, a user_id of sorts. Doing a full table scan of this would be a really bad idea.
Here is what you can do providing you have the user_id:
$users = $mongo->users->find(['_id' => ['$in' => [1,2,3,4,5,6,7,8,9]]]);
// Set some variables which will help us perform the detail queries
$cityIds = [];
$rideIds = [];
$userResults = [];
$cityResults = [];
$rideResults = [];
// Iterate through our users.
foreach($users as $_id => $user){
// We store the MongoId for use in queries
$cityIds[] = $user['city_id'];
$rideIds[] = $user['ride_id'];
// We then store the user result itself so we don't
// Do this query multiple times.
$userResults[$_id] = $user;
}
// Now, let's get our first details.
$cityResults = iterator_to_array(
$mongo->cities->find(['_id' => ['$in' => $cityIds]])
);
// And our ride details
$rideResults = iterator_to_array(
$mongo->rides->find(['_id' => ['$in' => $rideIds]])
);
// Now let's loop and echo
foreach($userResults as $k => $user){
echo $user['name'] .
' lives in ' .
$cityResults[$user['city_id']]['name'] .
' who drives a ' .
$rideResults[$user['ride_id']]['name'];
}
Something like that would do the trick.
Here I assume that your user schema has a city and ride ID in it respectively and that the two ID fields store an ObjectId (_id) of a city and ride row; this seems to be the most logical schema.

Answer 2

Nest the for loops inside of each other.
<?php
foreach ($details as $doc) {
foreach ($place as $city) {
foreach ($car as $ride) {
echo $doc['name'] . ' lives in '.$city['name'].' who drives a '.$ride['name'].'<br/>';
}
}
}
?>
Thats how i do it when im trying to access data in multiple collections to form the output