Getting data from foreign key on view in Laravel 6 - php

Question

What I am trying to do, is to fetch a row from a table, using a foreign key inside it, that links to another table, and then display a specific column of that row inside a view.
For some context, this is a website about sport events. Inside the view, the user should be able to see the details of the clicked event. Inside those details should be the sport category and the sport. However, I can't find how to do so, in Laravel 6.5.
What I have:
Database tables:
sport_categories (id, name)
sports (id, sport_category_id, name)
events (id, title, sport_category_id, sport_id)
EventsController
public function show(Event $event)
{
return view('events.show', ['event' => $event]);
}
View
<div id="event-sport-category">
<span>Sport Category:</span>
<span id="show-event-sport-category-label">{{$event->sport_category_id}}</span>
</div>
<div id="event-sport">
<span>Sport:</span>
<span id="show-event-sport-label">{{$event->sport_id}}</span>
</div>
SportCategory Model (empty)
class SportCategory extends Model
{
//
}
Sport Model
class Sport extends Model
{
public function user()
{
return $this->belongsTo(User::class);
}
}
Event Model
class Event extends Model
{
public function user()
{
return $this->belongsTo(User::class);
}
}
Of course at this point what is returned to the view are just the id columns of the events table. How can I return the corresponding name of each id?

Answer 1

Acoording to your database setup:
sport_categories (id, name)
sports (id, sport_category_id, name)
events (id, title, sport_category_id, sport_id)
So.. In this response I'm assuming that:
A Category has many Sports
A Sport has many Events
Notice: Given the fact that a Sport already belongs to a Category, you shouldn't need to specify a category_sport_id key in the events table: the related sport row should already have it.
Now, to your question..
How can I return the corresponding name of each id ?
Defining Relationships.
In your Category.php model:
class SportCategory extends Model
{
protected $guarded = []; // <---
// ...
public function sports() // <---
{
return $this->hasMany(Sport::class);
}
}
Your Sport.php model:
class Sport extends Model
{
protected $guarded = []; // <---
// ...
public function events() // <---
{
return $this->hasMany(Event::class);
}
public function category() // <---
{
return $this->belongsTo(SportCategory::class);
}
}
In your Event.php model:
class Event extends Model
{
protected $guarded = []; // <---
// ...
public function sport() // <---
{
return $this->belongsTo(Sport::class);
}
}
Notice: I added a protected $guarded = []; in each model, this is tell Laravel to include all the fields when returning it to the view. Read this.
Now that your relationships are been defined, you need to load the relationships before returning the variable to the view. Of course you could load the relationship in the view itself but to optimize your query you should eager load this objects like so (in this case, lazy eager loading because you are already resolving the object using Model Binding):
public function show(Event $event)
{
$event->load('sport.category'); // <---
return view('events.show', ['event' => $event]);
}
Now you should have this records in your $event variable: $event->sport and the nested $event->sport->category so in order to output them in your view just:
<p> {{ $event->sport->name }} </p>
<!-- ... -->
<p> {{ $event->sport->category->name }} </p>