Posted on: January 29, 2020 12:18 PM

Posted by: Renato

Categories: Variados PHP Laravel

Views: 2045

Eloquent é o nome do ORM (Object Relational Mapping) nativo no Framework PHP Laravel, que facilita (e muito) toda a manipulação do banco de dados. Não importa se é uma simples inserção de dados ou uma busca extremamente complexa com relações entre tabelas, o Eloquent dispõe de métodos de fácil compreensão e conta com uma documentação completa de como funciona dentro do Laravel.

Este artigo traz nove truques que todo desenvolvedor PHP deveria conhecer sobre o Eloquent, principalmente os que utilizam o Framework Laravel. Após a leitura, recomendo que faça a instalação, popule o banco de dados e comece a testar os métodos apresentados aqui.

Validação automática do modelo

Às vezes, pode ser conveniente validar automaticamente seu modelo quando recebe uma inserção ou atualização de dados. Isto é facilmente alcançado com o Laravel através do uso de eventos do Modelo.

class Cliente extends Eloquent
{
    public static $autoValidates = true;
    protected static $rules = [];
    protected static function boot()
    {
        parent::boot();
        // or static::creating, or static::updating
        static::saving(function($model)
        {
            if ($model::$autoValidates) {
                return $model->validate();
            }
        });
    }
    public function validate()
    {
    }
}

Proibir atualizações

Existem casos onde o seu registro, uma vez criado, não deve sofrer alterações. Para aumentar a garantia de que uma tabela do seu banco de dados não sofrerá atualizações basta informar, no próprio Modelo, que a ação de atualizar deve ser barrada.

class Cliente extends Eloquent
{
    protected static function boot()
    {
        parent::boot();
        static::updating(function($model)
        {
            return false;
        });
    }
}

Relações condicionais

Essa é mais uma facilidade que o Laravel traz com a sua forma de construir relações entre tabelas, as relações que só existirão caso alguma condição seja atendida. Basta usar métodos do Eloquent na própria função.

class Cliente extends Model
{
    public function category()
    {
        return $this->belongsTo('Cupom', 'cupom_id')
            ->where('usuario_id', Auth::user()->id);
    }
}

Expressões da Sintaxe “Where”

Uma busca utilizando o método “where” pode ser feita de várias formas. Pode-se usar operadores (linha 1), mas por padrão o método “where” sempre busca utilizando o operador “=”, portanto não é necessário informá-lo (linha 3). Há também a forma mais abreviada que o Laravel Eloquent proporciona, onde é necessário apenas informar o nome da coluna que deseja utilizar na busca após o termo “where”, como um método (linha 5).

$cupons = Cupom::where('categoria', '=', 3)->get();
$cupons = Cupom::where('categoria', 3)->get();
$cupons = Cupom::whereCategoria(3)->get();

Query Builder: Having Raw

Os métodos o Laravel Eloquent também aceitam expressões Raw, o que facilita muito a escrita de uma busca mais complexa no banco de dados. É possível utilizar métodos Eloquent juntamente com o método estático “raw” da classe “DB”, que já é nativa do Laravel.

SELECT *, COUNT(*) FROM cupons GROUP BY categoria_id HAVING count(*) > 1;
DB::table('cupons')
    ->select('*', DB::raw('COUNT(*) as cupons_count'))
    ->groupBy('categoria_id')
    ->having('cupons_count', '>', 1)
    ->get();

Filtro de data simples

O Carbon é utilizado como padrão para manipular datas no Laravel. Portanto, a busca no banco de dados, quando feita por data, fica muito fácil de compreender devido aos métodos do Laravel Eloquent.

$q->whereDate('created_at', date('Y-m-d'));
$q->whereDay('created_at', date('d'));
$q->whereMonth('created_at', date('m'));
$q->whereYear('created_at', date('Y'));

Opções na hora de inserir ou atualizar dados

Dependendo da necessidade do sistema, existem campos da tabela que só podem sofrer alterações se alguma condição for atendida. O Laravel Eloquent permite a criação de métodos para executar este controle.

// src/Illuminate/Database/Eloquent/Model.php
public function save(array $options = [])
// src/Illuminate/Database/Eloquent/Model.php
protected function performUpdate(Builder $query, array $options=[])
{
    if ($this->timestamps && array_get($options, 'timestamps', true))
    {
        $this->updateTimestamps();
    }
}
$cupom = Cupom::find($id);
$cupom->updated_at = '2019-01-20 00:00:00';
$cupom->save(['timestamps'=>false]);

Busca aleatória de dados

Por permitir o uso de expressões Raw em seu métodos, o Eloquent consegue realizar buscas randômicas sem precisar de recursos externos.

$cupons = Cupom::orderByRaw('RAND()')->take(10)->get();

UUID como chave primária

O Laravel Eloquent também oferece ferramentas para trabalhar com sistemas Multitenancy (com dois ou mais bancos de dados). Em casos como esse é mais interessante utilizar o UUID como chave primária. Isso é facilmente alcançado com a instalação de um pacote e criação de uma trait.

use Ramsey\Uuid\Uuid;
trait UUIDModel
{
    public $incrementing = false;
    protected static function boot()
    {
        parent::boot();
        static::creating(function ($model)
        {
            $key = $model->getKeyName();
            if (empty($model->{$key})) {
                $model->{$key} = (string) $model->generateNewUuid();
            }
        });
    }
    public function generateNewUuid()
    {
        return Uuid::uuid4();
    }
}

Essa é a ponta do iceberg de funções, truques e facilitadores do Laravel Eloquent. Se você busca um código limpo, expressivo, de fácil compreensão, o Laravel Eloquent cairá como uma luva. Para testar as funcionalidades do Laravel Eloquent, basta realizar a instalação do Laravel e popular o seu banco de dados.

• https://imasters.com.br/banco-de-dados/aprenda-9-truques-para-o-eloquent-laravel
• https://laravel-news.com/eloquent-tips-tricks

20 Laravel Eloquent Tips and Tricks

OCTOBER 27, 2018 / POVILASKOROP

Eloquent ORM seems like a simple mechanism, but under the hood, there’s a lot of semi-hidden functions and less-known ways to achieve more with it. In this article, I will show you a few tricks.

1. Increments and Decrements

Instead of this:

$article = Article::find($article_id);
$article->read_count++;
$article->save();

You can do this:

$article = Article::find($article_id);
$article->increment('read_count');

Also these will work:

Article::find($article_id)->increment('read_count');
Article::find($article_id)->increment('read_count', 10); // +10
Product::find($produce_id)->decrement('stock'); // -1

2. XorY methods

Eloquent has quite a few functions that combine two methods, like “please do X, otherwise do Y”.

Example 1 – findOrFail():

Instead of:

$user = User::find($id);
if (!$user) { abort (404); }

Do this:

$user = User::findOrFail($id);

Example 2 – firstOrCreate():

Instead of:

$user = User::where('email', $email)->first();
if (!$user) {
  User::create([
    'email' => $email
  ]);
}

Do just this:

$user = User::firstOrCreate(['email' => $email]);

3. Model boot() method

There is a magical place called boot() in an Eloquent model where you can override default behavior:

class User extends Model
{
    public static function boot()
    {
        parent::boot();
        static::updating(function($model)
        {
            // do some logging
            // override some property like $model->something = transform($something);
        });
    }
}

Probably one of the most popular examples is setting some field value at the moment of creating the model object. Let’s say you want to generate UUID field at that moment.

public static function boot()
{
  parent::boot();
  self::creating(function ($model) {
    $model->uuid = (string)Uuid::generate();
  });
}

4. Relationship with conditions and ordering

This is a typical way to define relationship:

public function users() {
    return $this->hasMany('App\User');    
}

But did you know that at this point we can already add where or orderBy?
For example, if you want a specific relationship for some type of users, also ordered by email, you can do this:

public function approvedUsers() {
    return $this->hasMany('App\User')->where('approved', 1)->orderBy('email');
}

5. Model properties: timestamps, appends etc.

There are a few “parameters” of an Eloquent model, in the form of properties of that class. The most popular ones are probably these:

class User extends Model {
    protected $table = 'users';
    protected $fillable = ['email', 'password']; // which fields can be filled with User::create()
    protected $dates = ['created_at', 'deleted_at']; // which fields will be Carbon-ized
    protected $appends = ['field1', 'field2']; // additional values returned in JSON
}

But wait, there’s more:

protected $primaryKey = 'uuid'; // it doesn't have to be "id"
public $incrementing = false; // and it doesn't even have to be auto-incrementing!
protected $perPage = 25; // Yes, you can override pagination count PER MODEL (default 15)
const CREATED_AT = 'created_at';
const UPDATED_AT = 'updated_at'; // Yes, even those names can be overridden
public $timestamps = false; // or even not used at all

And there’s even more, I’ve listed the most interesting ones, for more please check out the code of default abstract Model class and check out all the traits used.

6. Find multiple entries

Everyone knows the find() method, right?

$user = User::find(1);

I’m quite surprised how few people know about that it can accept multiple IDs as an array:

$users = User::find([1,2,3]);

7. WhereX

There’s an elegant way to turn this:

$users = User::where('approved', 1)->get();

Into this:

$users = User::whereApproved(1)->get(); 

Yes, you can change the name of any field and append it as a suffix to “where” and it will work by magic.

Also, there are some pre-defined methods in Eloquent, related to date/time:

User::whereDate('created_at', date('Y-m-d'));
User::whereDay('created_at', date('d'));
User::whereMonth('created_at', date('m'));
User::whereYear('created_at', date('Y'));

8. Order by relationship

A little more complicated “trick”. What if you have forum topics but want to order them by latest post? Pretty common requirement in forums with last updated topics on the top, right?

First, describe a separate relationship for the latest post on the topic:

public function latestPost()
{
    return $this->hasOne(\App\Post::class)->latest();
}

And then, in our controller, we can do this “magic”:

$users = Topic::with('latestPost')->get()->sortByDesc('latestPost.created_at');

9. Eloquent::when() – no more if-else’s

Many of us write conditional queries with “if-else”, something like this:

if (request('filter_by') == 'likes') {
    $query->where('likes', '>', request('likes_amount', 0));
}
if (request('filter_by') == 'date') {
    $query->orderBy('created_at', request('ordering_rule', 'desc'));
}

But there’s a better way – to use when():

$query = Author::query();
$query->when(request('filter_by') == 'likes', function ($q) {
    return $q->where('likes', '>', request('likes_amount', 0));
});
$query->when(request('filter_by') == 'date', function ($q) {
    return $q->orderBy('created_at', request('ordering_rule', 'desc'));
});

It may not feel shorter or more elegant, but the most powerful is passing of the parameters:

$query = User::query();
$query->when(request('role', false), function ($q, $role) { 
    return $q->where('role_id', $role);
});
$authors = $query->get();

10. BelongsTo Default Models

Let’s say you have Post belonging to Author and then Blade code:

{{ $post->author->name }}

But what if the author is deleted, or isn’t set for some reason? You will get an error, something like “property of non-object”.

Of course, you can prevent it like this:

{{ $post->author->name ?? '' }}

But you can do it on Eloquent relationship level:

public function author()
{
    return $this->belongsTo('App\Author')->withDefault();
}

In this example, the author() relation will return an empty App\Author model if no author is attached to the post.

Furthermore, we can assign default property values to that default model.

public function author()
{
    return $this->belongsTo('App\Author')->withDefault([
        'name' => 'Guest Author'
    ]);
}

11. Order by Mutator

Imagine you have this:

function getFullNameAttribute()
{
  return $this->attributes['first_name'] . ' ' . $this->attributes['last_name'];
}

Now, you want to order by that full_name? This won’t work:

$clients = Client::orderBy('full_name')->get(); // doesn't work

The solution is quite simple. We need to order the results after we get them.

$clients = Client::get()->sortBy('full_name'); // works!

Notice that the function name is different – it’s not orderBy, it’s sortBy.

12. Default ordering in global scope

What if you want to have User::all() always be ordered by name field? You can assign a global scope. Let’s go back to the boot() method, which we mentioned already above.

protected static function boot()
{
    parent::boot();

    // Order by name ASC
    static::addGlobalScope('order', function (Builder $builder) {
        $builder->orderBy('name', 'asc');
    });
}

Read more about Query Scopes here.

13. Raw query methods

Sometimes we need to add raw queries to our Eloquent statements. Luckily, there are functions for that.

// whereRaw
$orders = DB::table('orders')
    ->whereRaw('price > IF(state = "TX", ?, 100)', [200])
    ->get();

// havingRaw
Product::groupBy('category_id')->havingRaw('COUNT(*) > 1')->get();

// orderByRaw
User::where('created_at', '>', '2016-01-01')
  ->orderByRaw('(updated_at - created_at) desc')
  ->get();

14. Replicate: make a copy of a row

Short one. Without deep explanations, here’s the best way to make a copy of database entry:

$task = Tasks::find(1);
$newTask = $task->replicate();
$newTask->save();

15. Chunk() method for big tables

Not exactly Eloquent related, it’s more about Collection, but still powerful – to process bigger datasets, you can chunk them into pieces.

Instead of:

$users = User::all();
foreach ($users as $user) {
    // ...

You can do:

User::chunk(100, function ($users) {
    foreach ($users as $user) {
        // ...
    }
});

16. Create additional things when creating a model

We all know this Artisan command:

php artisan make:model Company

But did you know there are three useful flags to generate related files to the model?

php artisan make:model Company -mcr

• -m will create a migration file
• -c will create a controller
• -r will indicate that controller should be resourceful

17. Override updated_at when saving

Did you know that ->save() method can accept parameters? As a result, we can tell it to “ignore” updated_at default functionality to be filled with current timestamp. See this:

$product = Product::find($id);
$product->updated_at = '2019-01-01 10:00:00';
$product->save(['timestamps' => false]);

Here we’re overriding default updated_at with our pre-defined one.

18. What is the result of an update()?

Have you ever wondered what this code actually returns?

$result = $products->whereNull('category_id')->update(['category_id' => 2]);

I mean, the update is performed in the database, but what would that $result contain?

The answer is affected rows. So if you need to check how many rows were affected, you don’t need to call anything else – update() method will return this number for you.

19. Transform brackets into an Eloquent query

What if you have and-or mix in your SQL query, like this:

... WHERE (gender = 'Male' and age >= 18) or (gender = 'Female' and age >= 65)

How to translate it into Eloquent? This is the wrong way:

$q->where('gender', 'Male');
$q->orWhere('age', '>=', 18);
$q->where('gender', 'Female');
$q->orWhere('age', '>=', 65);

The order will be incorrect. The right way is a little more complicated, using closure functions as sub-queries:

$q->where(function ($query) {
    $query->where('gender', 'Male')
        ->where('age', '>=', 18);
})->orWhere(function($query) {
    $query->where('gender', 'Female')
        ->where('age', '>=', 65); 
})

20. orWhere with multiple parameters

Finally, you can pass an array of parameters to orWhere().
“Usual” way:

$q->where('a', 1);
$q->orWhere('b', 2);
$q->orWhere('c', 3);

You can do it like this:

$q->where('a', 1);
$q->orWhere(['b' => 2, 'c' => 3]);

If you enjoyed these Eloquent tips, check out my online course Eloquent: Expert Level and learn about creating relationships, querying data effectively and exploring Eloquent features that you may not know about.

Renato

Developer

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