Laravel 模型读取数据操作

小咪咪 2023-10-06 16:12 17阅读 0赞

## 创建模型 ##

php artisan make:model User       // 默认对应的表是 users
    php artisan make:model AbCd       // 默认对应的表是 ab_cds
    /**
    规则：
        1. 除第一个大写字母，其他大写字母前都加上下划线
        2. 所有的大写字母改成小写
        3. 末尾加 s
    */

## 模型读取数据 ##

App\User::all();                           // 返回包含所有对象的集合
    \App\User::where('name', 'John')->first(); // 返回对象
    \App\User::where('id', 1)->value('name');  // 返回值，例如 'leon'
    \App\User::find(3);                        // 返回主键等于 3 的对象
    \App\User::find([1, 2]);                   // 返回主键等于 1 和 2 的对象的集合
    \App\User::pluck('age');                   // 返回包含字段值的集合
    \App\User::pluck('age', 'id');             // 返回关联集合 id => age，pluck 最多 2 个参数
    \App\User::count();                        // 返回记录总数
    \App\User::max('id');                      // 返回数字，库没有任何记录返回 null
    \App\User::min('id');                      // 返回数字，库没有任何记录返回 null
    \App\User::avg('age');                     // 返回数字，库没有任何记录返回 null，同名 averge
    \App\User::sum('salary');                  // 返回数字，库没有任何记录返回 0

### where ###

where('votes', '=', 100)
    where('votes', 100)
    where('votes', '>=', 100)
    where('votes', '<>', 100)
    where('name', 'like', 'T%')
    where([
        ['status', '=', '1'],
        ['subscribed', '<>', '1'],
    ])
    where('votes', '>', 100)->orWhere('name', 'John')
    whereBetween('votes', [1, 100])           // 包含了 1 和 100
    whereNotBetween('votes', [1, 100])
    whereIn('id', [1, 2, 3])
    whereNotIn('id', [1, 2, 3])
    whereNull('last_name')
    whereNotNull('updated_at')
    whereDate('created_at', '2016-12-31')   // where date(created_at) = '2016-12-31')
    whereMonth('created_at', '12')
    whereDay('created_at', '31')
    whereYear('created_at', '2016')
    whereTime('created_at', '=', '11:20:45')
    whereColumn('first_name', 'last_name')        // 判断两个字段 相等
    whereColumn('updated_at', '>', 'created_at')
    
    whereColumn([
        ['first_name', '=', 'last_name'],
        ['updated_at', '>', 'created_at']
    ])
    
    where('finalized', 1)->exists();      // 返回 true 或者 false
    // select exists(select * from `xxx` where `finalized` = 1) as `exists`
    where('finalized', 1)->doesntExist();
    // 运行的 SQL 和上面的一样，Laravel 把运行结果取反就达成目的了
    
    where('name', '=', 'John')
    ->orWhere(function ($query) {
          // 传入闭包进 orWhere，避免全局 scope 产生不良影响
        $query->where('votes', '>', 100)
              ->where('title', '<>', 'Admin');
    })
    // where `name` = John or (`votes` > 100 and `title` <> Admin)
    
    whereExists(function ($query) {
        
        $query->selectRaw(1)
              ->from('orders')
              ->whereRaw('orders.user_id = users.id');
    })   
    // where exists ( select 1 from orders where orders.user_id = users.id )
    
    ->whereRaw('price > IF(state = "TX", ?, 100)', [200])->get();
    // IF 用法：IF(expr1,expr2,expr3)   
    // 如果 (expr1 <> 0 and expr1 <> NULL)，那么 expr1 就是 true。

### json ###

$users = \App\User::where('options->language', 'en')
                    ->get();
    // select * from `users` where json_unquote(json_extract(`options`, '$."language"')) = 'en'
    
    $users = \App\User::where('preferences->dining->meal', 'salad')
                    ->get();
    // select * from `users` where json_unquote(json_extract(`preferences`, '$."dining"."meal"')) = 'salad'
    
    $users = \App\User::whereJsonLength('options->languages', 0)
                    ->get();
    // select * from `users` where json_length(`options`, '$."languages"') = 0
    
    $users = \App\User::whereJsonLength('options->languages', '>', 1)
                    ->get();
    // select * from `users` where json_length(`options`, '$."languages"') > 1

App\User::orderBy('date')->where('active', false)->chunk(100, function ($users) {
          // 取每 100 个一组
        foreach ($users as $user) {
        
            // ...
            // return false;                                           // 随时可以退出
        }
    });      
    // select * from `users` where `active` = 0 order by `date` asc limit 3 offset 0
    // select * from `users` where `active` = 0 order by `date` asc limit 3 offset 3
    // 注意，laravel 把 false 转化成了 0
    
    
    // 不会出现 chunk 结束后，还有很多记录没被处理的情况
    \App\User::where('active', false)->orderBy('date')
        ->chunkById(100, function ($users) {
        
            foreach ($users as $user) {
        
                \App\User::where('id', $user->id)
                    ->update(['active' => true]);
            }
        });
    // select * from `users` where `active` = 0 order by `date` asc, `id` asc limit 3
    // select * from `users` where `active` = 0 and `id` > 3 order by `date` asc, `id` asc limit 3

### select ###

$users = \App\User::select('name', 'email as user_email')->get();
    
    $users = \App\User::distinct()->get();
    // select distinct * from `users1`
    
    $query = \App\User::select('name');
    $users = $query->addSelect('age')->get();
    // select `name`, `age` from `users`
    
    ->selectRaw('department, SUM(price) as total_sales')
    ->groupBy('department')
    ->havingRaw('SUM(price) > ?', [2500])
    ->orderByRaw('updated_at - created_at DESC')
    ->get();
    // select department, SUM(price) as total_sales from `destinations` group by `department` having SUM(price) > 2500 order by updated_at - created_at DESC

### join 和 union ###

# inner join
    ->join('contacts', 'users.id', '=', 'contacts.user_id')
    ->join('orders', 'users.id', '=', 'orders.user_id')
    ->select('users.*', 'contacts.phone', 'orders.price')
    ->get();
    
    # left join
    
    ->leftJoin('posts', 'users.id', '=', 'posts.user_id')
    ->get();
    
    # right join
    
    ->rightJoin('posts', 'users.id', '=', 'posts.user_id')
    ->get();
    
    # cross join
    
    ->crossJoin('colours')
    ->get();
    
    # 高级 join
    
    ->join('contacts', function ($join) {
        
        $join->on('users.id', '=', 'contacts.user_id')->orOn('users.pid', '=', 'contacts.pid');
    })
    ->get();
    // select * from `users` 
    //     inner join 
    // `contacts` 
    //     on `users`.`id` = `contacts`.`user_id` or `users`.`pid` = `contacts`.`pid`
    
    
    ->join('contacts', function ($join) {
        
        $join->on('users.id', '=', 'contacts.user_id')
            ->where('contacts.user_id', '>', 5);
    })
    ->get();
    // select * from `users` inner join `contacts` 
    //     on
    // `users`.`id` = `contacts`.`user_id` and `contacts`.`user_id` > 5
    
    
    # union
    $first = App\User::whereNull('first_name');
    
    $users = App\Student::whereNull('last_name')
                ->union($first)
                ->get();
    // (select * from `students` where `last_name` is null) union (select * from `users` where `first_name` is null)
    
    # unionAll 和 union 参数一样
    // unionAll 不会去除重复值

### 排序、分组和分页 ###

orderBy('name', 'desc')
    
    latest()                // === orderBy('created_at', 'desc')
    
    inRandomOrder()
    // order by RAND()
    
    ->groupBy('account_id')->having('account_id', '>', 100)
    
    ->groupBy('site', 'qianjinyike.com')->having('account_id', '>', 100)
    
    skip(10)->take(5)        // 等价于 offset(10)->limit(5)
    // limit 5 offset 10

### 分支执行 sql ###

// $role 有值才会执行闭包
    $role = $request->input('role');
    
    $users = \App\User::when($role, function ($query) use ($role) {
        
                        return $query->where('role_id', $role);
                    })
                    ->get();
    
    // $role 有值执行第一个闭包，否则执行第二个闭包
    $sortBy = null;
    $users = \App\User::when($sortBy, function ($query, $sortBy) {
        
                        return $query->orderBy($sortBy);
                    }, function ($query) {
        
                        return $query->orderBy('name');
                    })
                    ->get();

## 刷新模型 ##

$flight = App\Flight::where('number', 'FR 900')->first();
    $freshFlight = $flight->fresh();  // 去数据库里面重新取了一次
    
    $flight = App\Flight::where('number', 'FR 900')->first();
    $flight->number = 'FR 456';
    $flight->refresh();
    $flight->number; // "FR 900"

## 游标 ##

cursor 允许你使用游标来遍历数据库数据，一次只执行单个查询。在处理大数据量请求时 cursor 方法可以大幅度减少内存的使用：

foreach (Flight::where('foo', 'bar')->cursor() as $flight) {
        
        //
    }
    
    $users = App\User::cursor()->filter(function ($user) {
        
        return $user->id > 500;
    });

## 高级子查询 ##

Destination::addSelect(['last_flight' => Flight::select('name')
        ->whereColumn('destination_id', 'destinations.id')
        ->orderBy('arrived_at', 'desc')
        ->latest()
        ->limit(1)
    ])->get();
    // select `destinations`.*, (select `name` from `flights` where `destination_id` = `destinations`.`id` order by `arrived_at` desc, `created_at` desc limit 1) as `last_flight` from `destinations`

## 未找到异常 ##

findOrFail 以及 firstOrFail 方法会取回查询的第一个结果。如果没有找到相应结果，则会抛出一个 Illuminate\\Database\\Eloquent\\ModelNotFoundException：

$model = App\Flight::findOrFail(1);
    
    $model = App\Flight::where('legs', '>', 100)->firstOrFail();

## 全局作用域 ##

// 可以自由在  app 文件夹下创建 Scopes 文件夹来存放
    <?php
    namespace App\Scopes;
    use Illuminate\Database\Eloquent\Scope;
    use Illuminate\Database\Eloquent\Model;
    use Illuminate\Database\Eloquent\Builder;
    
    class AgeScope implements Scope {
        
        public function apply(Builder $builder, Model $model)
        {
        
            $builder->where('age', '>', 200);
        }   // 使用 addSelect 而不是 select,可以避免覆盖
    }
    
    // 需要重写给定模型的 boot 方法并使用 addGlobalScope 方法
    <?php
    namespace App;
    use App\Scopes\AgeScope;
    use Illuminate\Database\Eloquent\Model;
    class User extends Model {
        
        protected static function boot() {
        
            parent::boot();
    
            static::addGlobalScope(new AgeScope);
        }
    }

# 添加作用域后，如果使用 User::all() 查询则会生成如下SQL语句：
    select * from `users` where `age` > 200

## 匿名全局作用域（专门用来处理单个模型） ##

<?php
    namespace App;
    use Illuminate\Database\Eloquent\Model;
    use Illuminate\Database\Eloquent\Builder;
    class User extends Model {
        
        protected static function boot() {
        
            parent::boot();
    
            static::addGlobalScope('age', function (Builder $builder) {
        
                $builder->where('age', '>', 200);
            });
        }
    }

## 移除全局作用域 ##

# 我们还可以通过以下方式，利用 age 标识符来移除全局作用：
    User::withoutGlobalScope('age')->get();
    
    # 移除指定全局作用域
    User::withoutGlobalScope(AgeScope::class)->get();
    
    # 移除几个或全部全局作用域
    User::withoutGlobalScopes([
        FirstScope::class, SecondScope::class
    ])->get();
    
    # 移除所有全局作用域
    User::withoutGlobalScopes()->get();

## 本地作用域 ##

<?php
    namespace App;
    use Illuminate\Database\Eloquent\Model;
    class User extends Model {
        
    
        public function scopePopular($query) {
        
            return $query->where('votes', '>', 100);
        }
    
        public function scopeActive($query) {
        
            return $query->where('active', 1);
        }
    }

# 在进行方法调用时不需要加上 scope 前缀
    $users = App\User::popular()->active()->orderBy('created_at')->get();
    
    $users = App\User::popular()->orWhere(function (Builder $query) {
        
        $query->active();
    })->get();
    
    $users = App\User::popular()->orWhere->active()->get();

## 动态范围 ##

<?php
    namespace App;
    use Illuminate\Database\Eloquent\Model;
    class User extends Model {
        
        public function scopeOfType($query, $type)
        {
        
            return $query->where('type', $type);
        }
    }

现在，你可以在范围调用时传递参数：

$users = App\User::ofType('admin')->get();