Laravel Defining Relationships - php

Question

I have one table named Content which is a master table like
Content : id content_name created_at updated_at
and another table Course like
Course table have many content_id
Course : id content_id course_name created_at updated_at
I have created relation like this.
Content Model
class Content extends Eloquent {
protected $table = 'contents';
protected $guarded = array('id');
public function course()
{
return $this->belongsTo('Course');
}
}
Course Model
class Course extends Eloquent {
protected $table = 'courses';
protected $guarded = array('id');
public function content()
{
return $this->hasMany('Content');
}
}
When i am fething the data like this
$courses=Course::find(1)->content;
It throws error like
SQLSTATE[42S22]: Column not found: 1054 Unknown column 'contents.course_id' in 'where clause' (SQL: select * from contents where contents.course_id = 1)
I am unable to rectify the problem in relations as I am new to laravel.

Answer 1

Close, but you have your relationships backwards. The table that has the foreign key is the one that belongsTo the other one. In this case, your course table has the foreign key content_id, therefore Course belongs to Content, and Content has one or many Courses.
class Content extends Eloquent {
public function course() {
return $this->hasMany('Course');
}
}
class Course extends Eloquent {
public function content() {
return $this->belongsTo('Content');
}
}

Answer 2

in your migrations(create_courses_table) , make sure to set the foreign key like that ,
$table->integer('content_id)->unsigned()->index();
$table->foreign('content_id')
->references('id')
->on('contents')
->onDelete('cascade');

Answer 3

I don't really understand your table design, maybe it should be something like this.
Taking your statement: "Course table have many content_id". I perceive that you are saying that 1 course can have multiple content, is that right? If yes, you might want to change your table design to something like below
Course
======
id
course_name
created_at
updated_at
Content
=======
id
course_id (set this as FK)
content_name
created_at
updated_at
migration code for content
public function up()
{
Schema::create('content', function(Blueprint $table)
{
$table->engine = 'InnoDB';
$table->increments('id');
$table->integer('course_id')->unsigned();
$table->string('content_name');
});
Schema::table('content',function($table)
{
$table->foreign('course_id')->references('id')->on('course')->onDelete('cascade');
});
}
Then in your model
class Course extends Eloquent
{
protected $table = 'course';
public function content()
{
return $this->hasMany('content', 'course_id', 'id');
}
}
class Content extends Eloquent
{
protected $table = 'content';
public function course()
{
return $this->belongsTo('course', 'course_id', 'id');
}
}
Then to access your data via eager loading
$course = Course::with('content')->get();
OR
$content = Content::with('course')->get();

Answer 4

This is about determining associations. Your associations should be:
Content
Content has many courses
class Content extends Eloquent {
protected $table = 'contents';
protected $guarded = array('id');
public function courses()
{
return $this->hasMany('Course');
}
}
Course
The course belongs to content.
class Course extends Eloquent {
protected $table = 'courses';
protected $guarded = array('id');
public function content()
{
return $this->belongsTo('Content');
}
}
So you can do query association.
For finding content -> courses:
$courses = Content::find(1)->courses;
For finding course -> content:
$content = Course::find(1)->content;