Commonly used Laravel Eloquent essential practical skills-Laravel-php.cn

Commonly used Laravel Eloquent essential practical skills

Eloquent ORM seems like a simple mechanism, but under the hood, there are many semi-hidden functions and little-known ways to achieve more functionality. In this article, I'll demonstrate a few tips.

1. Increment and decrement

To replace the following implementation:

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

Copy after login

You can do this:

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

Copy after login

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

Copy after login

2. Execute method If method X fails to execute, method Y will be executed."

Example 1 --

findOrFail()

: To replace the implementation of the following code:

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

Copy after login

You can write like this:

$user = User::findOrFail($id);

Copy after login

Example 2 --

firstOrCreate()

: To replace the implementation of the following code:

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

Copy after login

Just write this:

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

Copy after login

3 . The model's boot() method

In an Eloquent model, there is a magical place called

boot()

, where you can override the default behavior: <div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false">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); }); } }</pre><div class="contentsignin">Copy after login</div></div> Setting the values of certain fields when creating a model object is probably one of the most popular examples. Let's take a look at what you should 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();
  });
}

Copy after login

4. Association with conditions and sorting

General way to define association:

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

Copy after login

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, you can Do this:

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

Copy after login

5. Model characteristics: time, append, etc.

The Eloquent model has some parameters, using the attribute form of the class. 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
}

Copy after login

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

Copy after login

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? <div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false">$user = User::find(1);</pre><div class="contentsignin">Copy after login</div></div>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]);

Copy after login

7. WhereX

There is an elegant way to This kind of code:

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

Copy after login

is converted into this kind of code:

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

Copy after login

Yes, you read it right, use the field name as a suffix and add it to the end of

where

, and it will pass The magic method works. 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'));

Copy after login

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();
}

Copy after login

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

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

Copy after login

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'));
}

Copy after login

There is a better way Method--Use

when()

<div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false">$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')); });</pre><div class="contentsignin">Copy after login</div></div> 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();

Copy after login

10. One-to-many return Default model object

Suppose there is a situation where you want to display the author of the article, and then the template code is:

{{ $post->author->name }}

Copy after login

But if the author's information is deleted or not set for some reason. The code will return an error such as "property of non-object".

Of course you can handle it like this:

{{ $post->author->name ?? '' }}

Copy after login

You can do this through the Eloquent relationship:

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

Copy after login

In this example, if the text does not have author information,

author ()

will return an empty App\Author model object. Furthermore, we can also assign default values to the properties in the default model object.

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

Copy after login

11. Sorting by assignment function

Imagine you have this code:

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

Copy after login

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

Copy after login

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

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

Copy after login

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

12. Default sorting under global scope

If you want

User::all()

always follow the name field What about sorting? You can assign it a global scope. Let's go back to boot() This method we mentioned above: <div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false">protected static function boot() { parent::boot(); // 按照 name 正序排序 static::addGlobalScope('order', function (Builder $builder) { $builder->orderBy('name', 'asc'); }); }</pre><div class="contentsignin">Copy after login</div></div>Extended reading Query scope.

13. 原生查询方法

有时候，我们需要在 Eloquent 语句中添加原生查询。幸运的是，确实有这样的方法。

// 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();

Copy after login

14. 复制：复制一行的副本

很简单。说明不是很深入，下面是复制数据库实体（一条数据）的最佳方法：

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

Copy after login

15. Chunk() 方法之大块数据

与 Eloquent 不完全相关,它更多的关于 Collection (集合),但是对于处理大数据集合,仍然是很有用的。你可以使用 chunk() 将这些数据分割成小数据块

修改前:

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

Copy after login

你可以这样做:

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

Copy after login

16. 创建模型时创建额外的东西

我们都知道Artisan命令：

php artisan make:model Company

Copy after login

但是，你知道有三个有用的标记可以为模型生成相关文件吗？

php artisan make:model Company -mcr

Copy after login

-m 将创建一个迁移文件
-c 将创建一个控制器
-r 表示控制器应该是一个资源控制器

17. 调用 save 方法的时候指定 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]);

Copy after login

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]);

Copy after login

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)

Copy after login

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);

Copy after login

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);
})

Copy after login

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);

Copy after login

你可以这样做：

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

Copy after login

我很确定还有更多隐藏的秘诀，但我希望至少上面的其中一些对你来说是新的。

推荐教程：《Laravel教程》

The above is the detailed content of Commonly used Laravel Eloquent essential practical skills. For more information, please follow other related articles on the PHP Chinese website!