Let's talk about the basic knowledge of field conversion in Laravel

In the process of using Laravel, we often encounter situations where fields need to be converted. In this article, we'll take a deep dive into the basics of field conversions in Laravel, including how to customize field conversion types.

Field conversion in Laravel is used to convert model attributes from one format to another to meet different business needs, such as converting the timestamp format saved in the database into a human-readable time format .

Laravel provides a wealth of field conversion types, including date, time, JSON, array and other types. By defining them in the model, we can easily convert model attributes. Let's take a look at how to define field conversion types in Laravel:

namespace App;

use Illuminate\Database\Eloquent\Model;

class Post extends Model
{
    protected $casts = [
        'published_at' => 'datetime',
        'meta' => 'array',
    ];
}

In the above example, we convert published_at to the datetime type, and meta is converted to the array type. In this way, when we get the Post model from the database, published_at will be automatically converted to a Carbon instance, and meta will be automatically converted is a PHP array.

In addition to Laravel's built-in field conversion types, we can also customize field conversion types to meet specific business needs. Let's see an example of a custom field conversion type:

namespace App\Models;

use Carbon\Carbon;
use Illuminate\Contracts\Database\Eloquent\CastsAttributes;

class Price implements CastsAttributes
{
    public function get($model, $key, $value, $attributes)
    {
        return $value / 100;
    }

    public function set($model, $key, $value, $attributes)
    {
        return $value * 100;
    }
}

In the above example, we have defined a custom field conversion type named Price to convert the model The property is converted from integer format in cents to floating point format in yuan. Among them, the get method is used to convert attributes when reading them from the database, and the set method is used to convert attributes when writing them to the database.

To use a custom field cast type in a model, we simply specify the type in the $casts attribute:

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Product extends Model
{
    protected $casts = [
        'price' => Price::class,
    ];
}

In the above example, we Convert the price attribute to the Price type, so that when we get the Product model, price will be automatically read from the database to Divided into integer format in units and converted to floating point format in yuan units.

In addition to using custom field conversion types in the model, we can also use field conversion types in the query builder to meet specific query needs. Let's see how to use field conversion types to query:

$posts = Post::where('published_at', '>', now()->subDays(7))->get();

In the above example, we query for articles published in the last 7 days. Laravel will automatically convert the value of the published_at field into a Carbon instance and compare it to the current time.

In short, field conversion is a very important feature in Laravel, which can help us easily convert model attributes to meet different business needs. Through the introduction of this article, I believe that readers have understood the basic knowledge of field conversion in Laravel, and I hope it can help readers use Laravel in actual projects.

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