Essential practical tips for Laravel Eloquent

Necessary practical skills for Laravel Eloquent

1. Increment and decrement

To replace the following implementation:

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

You can do this:

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

The following methods can also be implemented:

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

2. Execute the Use, for example "Please execute method X first, if method X fails, execute method Y".

Example 1 -- findOrFail():

To replace the implementation of the following code:

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

You can write like this:

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

Example 2 -- firstOrCreate():

To replace the implementation of the following code:

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

Just write it like this:

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

3. The model's boot() method

In an Eloquent model, there is a magical place called boot(), where you can override the default behavior:

class User extends Model
{
    public static function boot()
    {
        parent::boot();
        static::updating(function($model)
        {
            // 写点日志啥的
            // 覆盖一些属性，类似这样 $model->something = transform($something);
        });
    }
}

Set the values ​​of certain fields when creating the model object, probably the most One of the popular examples. Let’s take a look at what to do if you want to generate a UUID field when creating a model object.

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

4. Association with conditions and sorting

General way to define association:

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

Do you know? You can also add where or orderBy on the basis of the above,

For example, if you want to associate certain types of users and use the email field to sort at the same time, you can do this:

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

5. Model features: time, append, etc.

Some parameters of the Eloquent model are in the form of class attributes. The most commonly used ones are:

class User extends Model
{
    protected $table = 'users';
    protected $fillable = ['email', 'password']; // 可以被批量赋值字段，如 User::create() 新增时，可使用字段
    protected $dates = ['created_at', 'deleted_at']; // 需要被Carbon维护的字段名
    protected $appends = ['field1', 'field2']; // json返回时，附加的字段
}

Not only these, but also:

protected $primaryKey = 'uuid'; // 更换主键
public $incrementing = false; // 设置 不自增长
protected $perPage = 25; // 定义分页每页显示数量（默认15）
const CREATED_AT = 'created_at';
const UPDATED_AT = 'updated_at'; //重写 时间字段名
public $timestamps = false; // 设置不需要维护时间字段

There are more. I only listed some interesting features. Please refer to the document abstract Model class for details.

6. Query multiple records by ID

Everyone knows the find() method, right?

$user = User::find(1);

I am very surprised that few people know that this method can accept arrays of multiple IDs as parameters:

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

7. WhereX

There is an elegant way to This kind of code:

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

Convert to this kind of code:

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

Yes, you read it right, use the field name as a suffix and add it to where after, and it will run through the magic method.

In addition, there are some predefined methods related to time in Eloquent:

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. Sorting by relationship

A more complicated "technique". Do you want to sort forum topics by latest posts? It’s a common requirement to have the most recently updated topics in a forum at the top, right?

First, define a separate relationship for the latest post of the topic:

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

Then, in the controller, we can implement this "magic":

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

9. Eloquent::when() -- No more using if-else

Many people like to use "if-else" to write query conditions, 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'));
}

There is a better way Method--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 look very elegant, but its powerful function is to pass parameters:

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

10. BelongsTo default model

If There is a Post model attached to the Author model, and the following code can be written in the Blade template:

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

But what if the author is deleted, or is not set for some reason? You will get an error message like "non-existent object property".

Well, you can avoid it like this:

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

But you can do this effect at the Eloquent relational model level:

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

In this example, if the post has no author Otherwise, the author() relationship method will return an empty App\Author model object.

In addition, we can also assign a default attribute value to the default model.

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

11. Sorting by assignment function

Imagine you have this code:

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

Now, you want to sort by "full_name"? Found that there is no The effect:

$clients = Client::orderBy('full_name')->get(); //没有效果

The solution is very simple. We need to sort the results after getting them.

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

Note that the method names are different--it is not orderBy, but sortBy

12. Default sorting under global scope

What if you want User::all() to always sort by the name field? You can assign it a global scope. Let's go back to the boot() method we mentioned above:

protected static function boot()
{
    parent::boot();
    // 按照 name 正序排序
    static::addGlobalScope('order', function (Builder $builder) {
        $builder->orderBy('name', 'asc');
    });
}

Extended reading Query scope.

13. Native query method

Sometimes, we need to add native queries to Eloquent statements. Fortunately, there is a way.

// 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. Copy: Copy a row

It’s very simple. The explanation is not very in-depth, but here is the best way to copy a database entity (a piece of data):

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

15. Chunk() method of large chunks of data

is not completely related to Eloquent, it is more More about Collection (collection), but it is still very useful for processing large data collections. You can use chunk() to split this data into small data chunks

Before modification:

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

You can do this:

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

16. Add extra when creating the model Operation

We all know this Artisan command:

php artisan make:model Company

But you know that there are three very useful identifiers that can be used to generate model related files

php artisan make:model Company -mcr

-m Create migration files

-c Create controller file

-r Add resource operation method to controller

17. Specify updated_at

你知道 ->save() 方法可以接受参数吗? 我们可以通过传入参数阻止它的默认行为：更新 updated_at 的值为当前时间戳。

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

这样，我们成功在 save 时指定了 updated_at 的值。

18. update() 的结果是什么？

你是否想知道这段代码实际上返回什么？

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

我是说，更新操作是在数据库中执行的，但 $result 会包含什么？

答案是受影响的行。 因此如果你想检查多少行受影响， 你不需要额外调用其他任何内容 -- update() 方法会给你返回此数字。

19. 把括号转换成 Eloquent 查询

如果你有个 and 和 or 混合的 SQL 查询，像这样子的：

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

怎么用 Eloquent 来翻译它呢？ 下面是一种错误的方式：

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

顺序就没对。正确的打开方式稍微复杂点，使用闭包作为子查询：

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

20. 复数参数的 orWhere

终于，你可以传递阵列参数给 orWhere()。平常的方式：

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

你可以这样做：

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

更多laravel框架相关技术文章，请访问laravel教程栏目！

The above is the detailed content of Essential practical tips for Laravel Eloquent. For more information, please follow other related articles on the PHP Chinese website!