Laravel 7 query relationships tables - sql

Question

I need a bit of help with getting data from tables that are in relationship.
I have 2 tables: cards and statuses:
I have following data in cards table:
id_card | card_type
--------|----------
123 | tag
281 | card
455 | card
721 | tag
In statuses table I have:
id_status | id_card | status_date | status_type | status_company | status_user
----------|---------|-------------|-------------|----------------|------------
1 | 123 | 2018-12-04 | available | |
2 | 281 | 2018-12-04 | available | |
3 | 455 | 2018-12-04 | available | |
4 | 721 | 2019-03-26 | available | |
5 | 281 | 2020-01-25 | issued | Company A | User One
6 | 123 | 2020-01-10 | issued | Company B | User Two
7 | 281 | 2020-01-25 | available | |
8 | 123 | 2020-02-02 | lost | |
9 | 455 | 2020-02-14 | issued | Company C | Third User
For table cards I have following in Card model:
public function Status() {
return $this->hasMany('App\Status', 'id_card', 'id_card')
->orderBy('status_date', 'desc');
}
And for statuses table I have in Status model:
public function Card() {
return $this->hasOne('App\Card', 'id_card', 'id_card')
}
Now, how should I write a query, that would return me list of cards together with values from statuses table, but only with latest status for each card, like this:
id_card | card_type | status_type | status_date | status_company | status_user
--------|-----------|-------------|-------------|----------------|------------
123 | tag | lost | 2020-02-02 | |
281 | card | available | 2020-01-25 | |
455 | card | issued | 2020-02-14 | Company C | Third User
721 | tag | available | 2019-03-26 |
And is there a way, to also filter such a query i.e. to get only available cards:
id_card | card_type | status_type | status_date | status_company | status_user
--------|-----------|-------------|-------------|----------------|------------
281 | card | available | 2020-01-25 | |
721 | tag | available | 2019-03-26 | |
Thank you very much in advance :)

Answer 1

For getting all the cards having status_type 'available'
Card::join('statuses', 'cards.id_card', '=', 'statuses.id_card')
->where('statuses.status_type', 'available')
->select('cards.id_card', 'cards.card_type', 'statuses.status_type', 'statuses.status_date', 'statuses.status_company', 'statuses.status_user')
->get();
For getting latest status you can follow these steps,
Add following method in Card model
public function latestStatus()
{
return $this->hasOne('\App\Status')->latest();
}
Method latest() orders all rows by created_at desc, and takes the first one. If you don't have created_at column you can add it in statuses table.
$cards = Card::with('latestStatus')->get();
foreach ($cards as $card) {
echo $card->type . ' has latest status of ' . $card->latestStatus->status_type;
}
last but not the least, I think if you follow laravel conventions then you'll already have half of your problem solved.

Answer 2

Laravel is a framework that works better for you if you follow some conventions. The database models standards in Laravel in your case for Card and Status would be:
Then, you could simply have:
Status.php
use App\Card;
class Status extends Model
{
public function card()
{
return $this->hasOne(Card::class);
}
}
Card.php
use App\Status;
class Card extends Model
{
public function statuses()
{
return $this->hasMany(Status::class);
}
}
Finally, you could do:
$cards = App\Card::with(['statuses' => function($q){
$q->latest()->take(1);
}])->get();
Laravel will give out of the box a collection of Cards, with the last status attached.
To filter results based in related Status you could do:
$filter = 'available';
$cards = App\Card::with(['statuses' => function($q) use($filter) {
$q->where('status_type', $filter)->latest()->take(1);
}])->get();
Hope this helps to guide you in the right direction!

Answer 3

Firstly since you have a hasMany relationship, the naming should be plural.
public function Statuses() {
Defining an Accessor can help you on your status problem. In your Card.php model define it.
public function getStatusAttribute()
{
return $this->statuses->first();
}
Using the appends property on your Card.php model, to tell which properties should be serialized.
protected $appends = ['status'];
This will result in your model looking like so, when it is transformed to JSON.
{
"card_type": "tag",
"status": {
"id_card": 1,
"status_date": "2020-02-02",
"status_company": "Company C",
"status_user": "Third User"
}
}
If you are using it, in a Blade or PHP -context you can access like so.
$card->status; //your first status
For your query needs a simply where() clause combined with joining the table. For performance it would be smart to eager load statuses as you will access the first status, with() can be used for this.
Card::leftJoin('statuses', 'cards.id_card', 'statuses.id_card')
->where('statuses.status_type', 'available')
->select('cards.*')
->with('statuses')
->get();
Your naming of the columns is inconsistent with the Laravel naming convention and your data structure seems a little bit off, but this solves your problem, i would consider to rethink it.