如何使用Phalcon框架加入2个集合？ [重复]

Question

This question already has an answer here:

• how to join two tables in mongodb 3 answers

I have 2 collections which I would like to join together using the Phalcon PHP framework.

I would know how to do this in MySQL, however I am wondering if it is possible when using MongoDB, a non-relational database.

Assuming my collections are:

Robots

• _id
• name
• age

Robot Parts

• _id
• robot_id
• name
• quantity

</div>

Answer 1

Hey Shailen & welcome to StackOverflow :)

Even though MongoDB is not a relational database, it does allow joining of collections by using the aggregation framework which comes as part of MongoDB since version 3.2.

You should be able to achieve this with something like:

$results = RobotCollection::aggregate([
    [
        '$lookup' => [
            'from' => 'robot_parts',
            'localField' => '_id',
            'foreignField' => 'robot_id',
            'as' => 'parts'
        ]
    ]
]);

In this example, the robot document will have a new field added to it 'parts' (or whatever you name it in the 'as' field of the $lookup). The parts will be matched where robot_parts.robot_id = robots._id

You can learn more about the $lookup pipeline step here: https://docs.mongodb.com/manual/reference/operator/aggregation/lookup/#pipe._S_lookup