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Query, Join and accessing results. Not performing single query.

Hello, I'm here because I can't figure out how to manage this. It's more like an improvement on application, that is working as planed. But it's performing more than desired number of SQL queries.

Thats why I want to use join to reduce the number of queries. Supposing that I have the code:

Assuming that I have a well configured Robot Model, with all hasMany and belongsTo defined...

On controller listAction(), I have the code to fetch all the Robots:

$robotsQuery = Robots::query();
$robotsQuery->join("RobotBrand"); //The related brand of the robot, oneToMany 1..N

$this->view->allRobots = $robotsQuery->execute(); // Passing all the robots to the view

And then In the view, I list the robots:

<ul>
{% for robot in allRobots %}
    <li>{{ robot.name }} - {{ robot.RobotBrand.name }}</li>
{% endfor %}
</ul>

This code worked well, but when I took a look at the log of database executed queries, I notice that for each robot, another Query to select the brand was executed.

What am I doing wrong. The desired effect would be to bring together with each robot, at least the one to many related data.

With that I would be able to execute a single query to bring all the robots with brand data included.

Thankyou !



10.5k

I'm on 1.3x and always do joins with the query builder:

        $qb = $this->modelsManager->createBuilder()
            ->columns(["o.*", "c.*"])
            ->from([
                "c"=>"Common\\Models\\Company"
            ])
            ->leftJoin("Common\\Models\\Office",
                "c.id = o.companyId",
                "o");

        $rows = $qb->getQuery()->execute();


2.3k
Accepted
answer

I'm using version 2.0.9. @jymboche when you access the content of $qb->Office->something. How many SQL is executed behind the scenes !? In my case, when I do this kind of thing, for each result (that I access this way $aModel->anotherModel) behind the scenes a SELECT is executed to get data from another model. That was the point of the question.

In futher study, I noticed that I was misunderstanding the use of Models.

"If you want to access $aModel->AnotherModel->somePropertie of course you want all the data of AnotherModel."

For listing purposes, on a table for example, you may not need all the data from the related model. So:

$robotsQuery = Robots::query();
$robotsQuery->columns("id_robot, name, RobotBrand.name as robot_brand"); //List all columns that will be shown on view
$robotsQuery->join("RobotBrand"); //The related brand of the robot, oneToMany 1..N
$this->view->allRobots = $robotsQuery->execute();

On view

<ul>
{% for robot in allRobots %}
    <li>{{ robot.name }} - {{ robot.brand_name }}</li>
{% endfor %}
</ul>

This is the right way to get data for listing without consuming too much from database unnecessarily.

Thankyou !



10.5k
edited Feb '16

The above example i posted executes one query and the models are accessible via:

    foreach($rows as $row) {
        $row->o->id;
        $row->c->id;
    }

But yes, you can limit the columns by specifying them in the columns array. Generally a single query is preferred, especially when your database isn't on the same server.

You are joining RobotBrand, but you dont select any data from it. So when you access columns in view phalcon need to do query.

Thanks @Jurigag. I understood at the end what phalcon does behind the scenes, and it really makes sence. By trying to access the robot.RobotBrand I`m saing "hey give me all the data from RobotBrand". But thanks, this answers the question.