Laravel Eloquent模型属性

Question

在实例化扩展Laravel的Eloquent Model类的模型类之后,有没有办法确定属性/属性是否映射到表,因此可以保存到表中？

例如,我有一个announcements包含列的表id,text以及"created_by".

我怎么知道created_by属性,如果设置将被保存？

$announcement = new Announcement();

isset($announcement->created_by)如果我还没有明确设置该值,则可以理解地返回false.我已经尝试了从Eloquent模型类继承的各种函数,但到目前为止还没有工作.我正在寻找类似的东西:

$announcement->doesThisMapToMyTable('created_by')无论是否$announcement->created_by已设置,都返回true .

Answer 1

如果您的模型充满了数据,您可以:

$announcement = Announcement::find(1);

$attributes = $announcement->getAttributes();

isset($attributes['created_by']);

对于空模型(新模型),遗憾的是,您必须使用小型黑客获取列.将此方法添加到BaseModel:

<?php

class BaseModel extends Eloquent {

    public function getAllColumnsNames()
    {
        switch (DB::connection()->getConfig('driver')) {
            case 'pgsql':
                $query = "SELECT column_name FROM information_schema.columns WHERE table_name = '".$this->getTable()."'";
                $column_name = 'column_name';
                $reverse = true;
                break;

            case 'mysql':
                $query = 'SHOW COLUMNS FROM '.$this->getTable();
                $column_name = 'Field';
                $reverse = false;
                break;

            case 'sqlsrv':
                $parts = explode('.', $this->getTable());
                $num = (count($parts) - 1);
                $table = $parts[$num];
                $query = "SELECT column_name FROM ".DB::connection()->getConfig('database').".INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = N'".$table."'";
                $column_name = 'column_name';
                $reverse = false;
                break;

            default: 
                $error = 'Database driver not supported: '.DB::connection()->getConfig('driver');
                throw new Exception($error);
                break;
        }

        $columns = array();

        foreach(DB::select($query) as $column)
        {
            $columns[$column->$column_name] = $column->$column_name; // setting the column name as key too
        }

        if($reverse)
        {
            $columns = array_reverse($columns);
        }

        return $columns;
    }

}

从中扩展您的模型:

class Announcement extends BaseModel {

}

然后你将能够:

$columns = $announcement->getAllColumnsNames();

isset($columns['created_by']);

Answer 2

您可以使用SchemaFacade查找列,而不是将自己的查找编写到数据库内部:

use Illuminate\Support\Facades\Schema;

$announcement = new Announcement();
$column_names = Schema::getColumnListing($announcement->getTable());
if (isset($column_names['created_by'])) {
  // whatever you need
}

Answer 3

对于Laravel 5.4:

$hasCreatedAt = \Schema::hasColumn(app(Model::class)->getTable(), 'created_at');

    if($hasCreatedAt == true) {
       ...
    }