Relationships using Eloquent - php

Question

I'm using Eloquent in Laravel 5 and am a bit confused in relations between tables. These are existing tables of a software and cannot be altered.
I have the following tables that shows historical details of a student. All tables have model classes created.
student
-------
student_id (PK)
first_name
last_name
class
-----
class_id (PK)
name
section
year //2012, 2013 etc
student_id (FK)
result
------
result_id (PK)
class_id (FK)
month // jan, feb etc
status //pass or fail
Below are the details of each table
Student studies in a class for a particular year
Each class for that year will have 10 results (1 result for each month in an year)
Each result will contain the state for a test in a month (pass or fail)
I want to access objects based on the below examples. Can you guide on setting up relations in the model classes
student->class(2013)->result(jan)
result(feb)->class(2016)->student

Answer 1

First of all you should define the relationships between your models:
Result.php model
public function class(){
return $this->belongsTo('Class::class');
}
Class.php model
public function results(){
return $this->hasMany('Result::class');
}
public function student(){
return $this->belongsTo('Student::class');
}
Student.php model
public function classes(){
return $this->hasMany('Class::class');
}
Then, you can use some queries. For your first example student->class(2013)->result(jan):
$results = Student::find($student_id)->classes()->where('year', '2013')->results()->where('month', 'jan')->get();
Also, if you will need to search classes by year and results by month a lot of times, you can easily add some methods like this in your models:
Student.php model
public function classesByYear($year){
return $this->classes()->where('year', $year)->get();
}
Class.php model
public function resultsByMonth($month){
return $this->results()->where('month', $month)->get();
}
So the previous example will become:
$results = Student::find($student_id)->classesByYear('2013')->resultsByMonth('jan');
EDIT: Your tables are using a custom identifier, so you must implement protected $primaryKey = 'custom_id'; on each model.