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DaleLanto
DaleLanto

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Laravel 8- Eloquent Relationships Tutorial - One to Many Relationship

#php #laravel #erd #beginners

This is Part 2 of our Laravel 8 - Eloquent Relationships Tutorial

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Let's start by creating the database table
php artisan make:migration create_comments_table

go to app/database/migrations:

Schema::create('comments', function (Blueprint $table) { $table->id(); $table->foreignId('student_id'); $table->string('comment'); $table->timestamps(); });
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copy and save

run migration to create tables
php artisan migrate
check in your database if successful

Now let's create the model of comments
php artisan make:model Comment

models should be singular while the table is plural

One to Many Relationships

Go to app/Models and open the student model and the comment models

define the one to many relationship
in Models/Student.php

public function comment() { return $this->hasMany('App\Models\Comment'); }
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in Models/Comment.php

protected $fillable = [ 'student_id', 'comment', ]; public function student() { // return $this->belongsTo('Model', 'foreign_key', 'owner_key'); return $this->belongsTo('App\Models\Student','student_id','id'); }
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this will define the relationship between the two models

Create the Controllers and Routes

using the StudentController we made in part 1 lets create the function to create 3 comments under 1 student

go to app/Http/Controllers/StudentController

public function store_comment(){ $student = Student::find(1); $comment = new Comment; $comment->student_id = $student->id; $comment->comment = 'Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the indust'; $comment->save(); $comment = new Comment; $comment->student_id = $student->id; $comment->comment = 'king it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydne'; $comment->save(); $comment = new Comment; $comment->student_id = $student->id; $comment->comment = 'ed to be sure there isnt anything embarrassing hidden in the middle of text. All the Latin words,'; $comment->save(); dd($comment); }
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this is for example purposes of creating multiple comments only

create routes in app/routes/web.php

Route::get('/students/store/comment', [StudentController::class,'store_comment'])->name('storeComment');
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in your browser go to http://localhost:8000/students/store/comment to create 3 entry in the database

it should look similar to:

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Now change the index in StudentController to

public function index(){ $student = Student::find(1); dd($student->comment); }
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go to http://localhost:8000/students to check the models

it should look similar to:

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Hurray! We have successfully created our One to Many Relationship.

Now let's add queries when fetching our eloquent model

Fetching Students who have atleast 1 comment:

public function index(){ $student = Student::has('comment')->get(); dd($student); }
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Result:

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Fetching Students who doesn't have comments:

public function index(){ $student = Student::doesntHave('comment')->get(); dd($student); }
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Result:
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Fetching Students who have atleast 2 comments:

public function index(){ $student = Student::has('comment','>=',2)->get(); dd($student); }
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Fetching a Student with all his/her comments in descending order:

$student = Student::where('id',1)->with(['comment' => function($query) { $query->orderBy('id','desc'); }])->get(); dd($student);
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Result:

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Accessing the comments only:

foreach ($student as $comment){ dd($comment->comment); }
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Result:

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Accessing only specific columns in a comment

Change the comment Models/Student to

public function comment() { return $this->hasMany('App\Models\Comment','student_id')->orderBy('id','desc'); }
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then the code to get only specific column on a relation

$student = Student::where('id',1)->with(['comment:id,student_id,comment'])->get(); foreach ($student as $comment){ dd($comment->comment); }
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Result:
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Note: Primary Key id and Foreign Key student_id needs to be specificied for this to work

Get a student with a specific condition in the comments table:

$student = Student::whereHas('comment',function($query){ $query->where('comment','like','%king%'); })->get(); dd($student);
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Result:
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Get count of comments for each student

$student = Student::withCount('comment')->get(); dd($student);
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Result:
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Get count of comments for each student order by comment_count desc

$student = Student::withCount('comment')->orderBy('comment_count','desc')->get(); dd($student);
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Get count of comments for each student with a specific critera

  • get count of comments from students who have comments with the word king in it , result should only be 1 
$student = Student::withCount(['comment' => function($query) { $query->where('comment','like','%king%'); }])->get(); dd($student);
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Result:

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Awesome we've completed lots of exercises!
Click this link to proceed with the next tutorial - Many to Many Relationship!

Top comments (2)

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ndotie profile image
ndotie •

Thanks, this is nice tutorial

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imrancluster_35 profile image
Imran Sarder •

Thanks for your contribution.