Laravel 5.4 3个表之间的关系

Question

I am new in laravel, I already know how to join tables using the query builder. I just like to learn how to use relationships to avoid repetition of codes and to simplify it. I can join 2 tables, but I can't get the 3rd table.

I like to display employees assigned tasks information from the Tasks table, this table only has the project id that needs to be joined to the Projects table. Other employees can join in existing projects with other employees.

Employee model:

public function tasks()
{
    return $this->hasMany('\App\Task', 'project_coder', 'id');
}

Task model:

public function projects()
{
    return $this->hasMany('\App\Project', 'id', 'project_id');
}

Projects model:

public function belongsToTasks()
{
    return $this->belongsToMany('\App\Task', 'project_id', 'id');
}

I can only get the IDS from Task model. the ID will be use to fetch the project info from project tables. Unfortunately I cant do that part.

Employees controller:

public function show($id)
{
    $data = Employees::find($id);
    return view('show-employee')->withInfo($data);
}

Is it good practice to use query builder rather than relationships?

UPDATE :

Employees table

{
    "id":1,
    "name": "Juan"
}

Tasks table

{
    "id":1,    // autoincrement and will not be use for linking to other tables.
    "project_id": 1, //use to connect to project table
    "project_coder": 1 // use to connect to employees table
}

Projects table

{
    "id":1,
    "name": "First Project"
}

Answer 1

To deal with this is best to create pivot table like employee_task where table will have just two columns task_id and employee_id

then you can define in Task model

public function employees()
{
    return $this->belongsToMany('\App\Employee', 'employee_task');
}

and Employee model

public function tasks()
{
    return $this->belongsToMany('\App\Task', 'employee_task');
}

now you can see all employee tasks and rest of you relations work just fine

$data = Employees::find($id);
$data->tasks //you get all tasks assigned to this employee
$data->tasks()->first()->projects //you get all your projects for first task
$data->tasks()->first()->employees //all employees assigned to first task with this employee

Also recommend to you to lookup pivot tables, attach() , detach() and sync() functions. you can check it here : https://laravel.com/docs/5.7/eloquent-relationships#updating-many-to-many-relationships

UPDATE:

Ok I understand now what you are trying to do. You already have pivot table. I was little confused with your Project model which is not necessary.

You can remove your Project class if you have it just for this relation and update your model relations as I wrote above. You don't need project_id and project_coder_id in this relation. Also change the column names to more conventional names like employee_id and task_id as I mentioned or whatever your table names are. And you can rename employee_task pivot table name to your project table or you can rename it as well.

EDIT

When you use Project model for another data, you need to create 4th table as I mentioned above.

FINAL

• drop project_coder column in Tasks table - unecessary column
• create pivot table employees_task with employee_id , task_id
• create mentioned relations with pivot table

I assume that Project hasMany() tasks and Task only belongsTo() one project. So need to create these relations as well.

Then you can use these relations like this:

$employee = Employee::find($id);
$task = Task::find($id);
$project = Project::find($id);

$employee->tasks //all tasks assigned to employee
$task->employees //all employees assigned to task
$task->project //project info assigned to task
$employee->tasks()->first()->project //project data from first task of employee
$project->tasks()->first()->employees //all employees assigned to first project task