One to Many relationship in Laravel Eloquent giving undefine method - laravel

Question

I am having the said problem when defining one to many relationship with two models, the Student and Enrollment. When accessing the table from another table using:
$enrollment = App\Enrollment::first();
$enrollment->students()->first_name;
Im getting :
Illuminate\Database\QueryException with message 'SQLSTATE[42S22]: Column not found: 1054 Unknown column 'students.enrollment_id' in 'where clause' (SQL: select * from `students` where `students`.`enrollment_id` = 1 and `students`.`enrollment_id` is not null)'
However when I use :
$enrollment = App\Enrollment::first();
$enrollment->students()->first_name;
Im getting :
PHP error: Undefined property: Illuminate\Database\Eloquent\Relations\HasMany::$first_name on line 1
Can someone help me on this?
Enrollment
protected $fillable = [
'subject_code',
'subject_description',
'section',
'schedule',
'room_no',
'no_of_units'
];
public function students()
{
return $this->hasMany('App\Student');
}
Student
protected $fillable = [
'enrollments_id',
'student_no',
'first_name',
'last_name',
'middle_name',
'birthdate',
'fathers_name',
'mothers_name',
'phone_no',
'degree_id',
'city_id',
'address'
];
public function enrollment()
{
return $this->belongsTo('App\Enrollment');
}
Here's the table for the students and enrollment accordingly
Schema::create('students', function (Blueprint $table) {
$table->increments('id')->unsigned();
$table->integer('enrollments_id')->unsigned();
$table->integer('student_no');
$table->foreign('enrollments_id')->references('id')->on('enrollments')->unsigned();
$table->string('first_name');
$table->string('last_name');
$table->string('middle_name');
$table->date('birthdate');
$table->string('fathers_name');
$table->string('mothers_name');
$table->string('phone_no');
$table->string('address');
$table->integer('city_id');
$table->integer('degree_id');
$table->timestamps();
});
Schema::create('enrollments', function (Blueprint $table) {
$table->increments('id');
$table->string('subject_description');
$table->string('subject_code');
$table->time('schedule');
$table->string('room_no');
$table->integer('no_of_units');
$table->string('section');
$table->timestamps();
});

Answer 1

First of all what you exactly want
as per your question i am assuming you want 'enrollment has many students', for this relationship you need enrolment_id in students table not student_id in enrollment table.
and after that use
$students= Enrolment::find(id)->students;
it will return all students with the required enrollment id

Answer 2

That normal since you're trying to get property first_name from hasMany object, you should use get() method if you want to get Collection of objects (in your case collection of students) :
$enrollment->students()->get();
And if you want to get the first name you should specify the object you want to get the first_name from it, e.g :
$enrollment->students()->first()->first_name;
$enrollment->students()->last()->first_name;
If you want to get the attribute first_name of all the students you should use lists method, e.g :
$enrollment->students()->lists('first_name');
Output: collection of all students first names.
Hope this helps.
Update :
Try to remove ->unsigned() in :
$table->increments('id')->unsigned();
and also in :
$table->foreign('enrollments_id')->references('id')->on('enrollments')->unsigned();

Answer 3

When you call relations on an eloquent object it actually return you the relation not the exact objects
for eg: in your case
$enrollment->students() will return the relation
where as
$enrollment->students will return the eloquent object ( in belongs to, has one relations ) and collection/array of eloquent object/objects(in one to many , many to many relations )
simply if you are using it as an attribute you will get the actual result and relation query if it is called as a function
even if you get the relation you can get the results by calling get on top of that
$enrollment->students()->get()