Laravel模型默认值的相对时间now（）+ 24h

Question

I have a Model in Laravel where I want to set the default value to the time 24 hours from now.

This is how I create the table currently.

Schema::create('contact_credits', function (Blueprint $table) {
        $table->increments('id');
        $table->unsignedInteger('amount')->default(0);
        $table->unsignedInteger('amount_used')->default(0);
        $table->unsignedInteger('company_id');
        $table->foreign('company_id')->references('id')->on('companies');
        $table->dateTime('expires_at');//default value now + 24h
        $table->timestamps();
    });

I tried the following:

...->default(\DB::raw('DATE_ADD(NOW(), INTERVAL 24 HOUR)'));

But I keep getting errors when trying to migrate. How do I get this to work?

Answer 1

Apparently you can only use constant values as default values in MySQL with the exception of CURRENT_TIMESTAMP. Though, you cannot do expressions in a default value, so this is not useful for this case.

I ended up overriding the 'create'-method of my ContactCredit Model where I add the attribute and get the correct timestamp with Carbon. So for every instance that get's created, before it get's created it set's the attribute. See below.

class ContactCredit extends Eloquent
{
    protected $fillable = ['amount', 'expires_at'];
    protected $dates = ['expires_at'];

    public function company()
    {
        return $this->belongsTo('Company');
    }

    public static function create(array $attributes)
    {
        $attributes['expires_at'] = \Carbon\Carbon::now()->addHours(24);
        return parent::create($attributes);
    }    
}