CakePHP 3.x Query many Table objects with Pagination

Need Help
1

Context:
I’m working with CakePHP 3.x and I’m trying to build an ORM query with pagination. I have the tables Users, Topics and Areas. User can have many topics but just one area. This is the db model:

CREATE TABLE users (
id INT AUTO_INCREMENT PRIMARY KEY,
email VARCHAR(255) NOT NULL,
password VARCHAR(255) NOT NULL,
);
CREATE TABLE topics (
id INT AUTO_INCREMENT PRIMARY KEY,
user_id INT NOT NULL,
name VARCHAR(255),
description TEXT,
FOREIGN KEY user_key (user_id) REFERENCES users(id)
);
CREATE TABLE areas (
id INT AUTO_INCREMENT PRIMARY KEY,
title VARCHAR(255),
UNIQUE KEY (title)
);
CREATE TABLE users_areas (
user_id INT NOT NULL,
area_id INT NOT NULL,
PRIMARY KEY (user_id, area_id),
FOREIGN KEY area_key(area_id) REFERENCES areas(id),
FOREIGN KEY user_key(user_id) REFERENCES users(id)
);

What I need
I need to get all the Topics filtered by an area given.
I’m trying the next:

//1. get the area from the url (OK)
$area = $this->request->getQuery('area');

//2. Get the area from db to get the id
$myarea = $this->Areas->find()->where(['title' => $area])->first();

//3. Get all the users related to the area given
$users = $this->Users->find()->matching('Areas', function ($q){
            return $q->where(['Areas.id' => $myarea->id]);
          });

//4. Get the Topics and Paginate
$topics = $this->paginate($this->Topics->find('all')->innerJoinWith('Users', function ($q){
          return $q->where(['User.id' => $myarea->id]);
        }));

//5. Set the topics (OK)
$this->set(compact('topics'));
$this->set('_serialize', ['topics']);

I got tons of errors and I’m not sure how to build the query properly.

2

Given your table structure I’d say you can’t filter topics by an area unless you are filtering by users. Topics and areas have no direct relationship.

3

In closures you don’t have access to external variables unless you declare them. Like this

//2. Get the area from db to get the id
$myarea = $this->Areas->find()->where(['title' => $area])->first();

//3. Get all the users related to the area given
$users = $this->Users->find()->matching('Areas', function ($q) use ($myarea) {
    return $q->where(['Areas.id' => $myarea->id]);
});

The missing use () is why you get undefined var error