感觉好长时间没写东西了,一方面主要是自己的角色发生了变化,每天要面对各种各样的事情和突发事件,不能再有一个完整的长时间让自己静下来写代码,或者写文章。

另一方面现在公司技术栈不再停留在只有 Laravel + VUE 了,我们还有小程序、APP 等开发,所以我关注的东西也就多了。

接下来我还是会继续持续「高产」,把写技术文章当作一个习惯,坚持下去。

好了,废话不多说,今天来说一说「​​Eloquent: 修改器​​」。

一直想好好研究下 Eloquent。但苦于 Eloquent 有太多可研究的,无法找到一个切入点。前两天看一同事好像对这个「​​Eloquent: 修改器​​」了解不多,所以今天就拿它作为入口,扒一扒其实现源代码。

首先还是拿一个 Demo 为例:

Demo

<?php
namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Carbon\Carbon;

class Baby extends Model
{
protected $table = 'baby';
protected $appends = ['age'];

public function getAgeAttribute()
{
$date = new Carbon($this->birthday);
return Carbon::now()->diffInYears($date);
}
}


这个代码比较简单,就是通过已有属性 ​​birthday​​,计算 Baby 几岁了,得到 ​​age​​ 属性。

前端就可以直接拿到结果:

return $baby->age;


同样的,还有 ​​setXxxAttribute​​ 方法来定义一个修改器。

源代码

读代码还是从使用入手,如上通过 ​​$baby->age​​ 调用 ​​age​​ 属性,这个属性没在类中定义,所以只能通过 PHP 的魔术方法 ​​__get()​​ 调用了。

我们看看 ​​Model​​ 类的 ​​__get()​​ 方法:

/**
* Dynamically retrieve attributes on the model.
*
* @param string $key
* @return mixed
*/
public function __get($key)
{
return $this->getAttribute($key);
}


好了,我们开始解读源代码了:

/**
* Get an attribute from the model.
*
* @param string $key
* @return mixed
*/
public function getAttribute($key)
{
if (! $key) {
return;
}

// If the attribute exists in the attribute array or has a "get" mutator we will
// get the attribute's value. Otherwise, we will proceed as if the developers
// are asking for a relationship's value. This covers both types of values.
if (array_key_exists($key, $this->attributes) ||
$this->hasGetMutator($key)) {
return $this->getAttributeValue($key);
}

...
}


重点自然就在第二个 ​​if​​ 上,主要判断 ​​attributes​​ 数组中是否包含该属性,如果没有,则会执行函数 ​​$this->hasGetMutator($key)​​:

/**
* Determine if a get mutator exists for an attribute.
*
* @param string $key
* @return bool
*/
public function hasGetMutator($key)
{
return method_exists($this, 'get'.Str::studly($key).'Attribute');
}


这就对上了我们的 ​​Demo​​ 中自定义的函数 ​​getAgeAttribute()​​,也就返回 ​​true​​ 了。

接下来就是执行函数 ​​$this->getAttributeValue($key)​​,进而执行函数:​​return $this->mutateAttribute($key, $value);​

/**
* Get the value of an attribute using its mutator.
*
* @param string $key
* @param mixed $value
* @return mixed
*/
protected function mutateAttribute($key, $value)
{
return $this->{'get'.Str::studly($key).'Attribute'}($value);
}


好了,到此我们基本就知道了获取自定义 ​​Attribute​​ 的流程了。

相信解析 ​​set XxxAttribute​​ 也是很简单的。

总结

好长时间没写东西了,先从最简单的入手,练练手。解析 ​​Eloquent​​ 需要费很多脑细胞,接下来的一段时间我会围绕着这个主题好好研究下去,尽可能的全部解读一遍::

```. |____Capsule | |____Manager.php |____composer.json |____Concerns | |____BuildsQueries.php | |____ManagesTransactions.php |____Connection.php |____ConnectionInterface.php |____ConnectionResolver.php |____ConnectionResolverInterface.php |____Connectors | |____ConnectionFactory.php | |____Connector.php | |____ConnectorInterface.php | |____MySqlConnector.php | |____PostgresConnector.php | |____SQLiteConnector.php | |____SqlServerConnector.php |____Console | |____Factories | | |____FactoryMakeCommand.php | | |____stubs | | | |____factory.stub | |____Migrations | | |____BaseCommand.php | | |____FreshCommand.php | | |____InstallCommand.php | | |____MigrateCommand.php | | |____MigrateMakeCommand.php | | |____RefreshCommand.php | | |____ResetCommand.php | | |____RollbackCommand.php | | |____StatusCommand.php | |____Seeds | | |____SeedCommand.php | | |____SeederMakeCommand.php | | |____stubs | | | |____seeder.stub |____DatabaseManager.php |____DatabaseServiceProvider.php |____DetectsDeadlocks.php |____DetectsLostConnections.php |____Eloquent | |____Builder.php | |____Collection.php | |____Concerns | | |____GuardsAttributes.php | | |____HasAttributes.php | | |____HasEvents.php | | |____HasGlobalScopes.php | | |____HasRelationships.php | | |____HasTimestamps.php | | |____HidesAttributes.php | | |____QueriesRelationships.php | |____Factory.php | |____FactoryBuilder.php | |____JsonEncodingException.php | |____MassAssignmentException.php | |____Model.php | |____ModelNotFoundException.php | |____QueueEntityResolver.php | |____RelationNotFoundException.php | |____Relations | | |____BelongsTo.php | | |____BelongsToMany.php | | |____Concerns | | | |____InteractsWithPivotTable.php | | | |____SupportsDefaultModels.php | | |____HasMany.php | | |____HasManyThrough.php | | |____HasOne.php | | |____HasOneOrMany.php | | |____MorphMany.php | | |____MorphOne.php | | |____MorphOneOrMany.php | | |____MorphPivot.php | | |____MorphTo.php | | |____MorphToMany.php | | |____Pivot.php | | |____Relation.php | |____Scope.php | |____SoftDeletes.php | |____SoftDeletingScope.php |____Events | |____ConnectionEvent.php | |____QueryExecuted.php | |____StatementPrepared.php | |____TransactionBeginning.php | |____TransactionCommitted.php | |____TransactionRolledBack.php |____Grammar.php |____Migrations | |____DatabaseMigrationRepository.php | |____Migration.php | |____MigrationCreator.php | |____MigrationRepositoryInterface.php | |____Migrator.php | |____stubs | | |____blank.stub | | |____create.stub | | |____update.stub |____MigrationServiceProvider.php |____MySqlConnection.php |____PostgresConnection.php |____Query | |____Builder.php | |____Expression.php | |____Grammars | | |____Grammar.php | | |____MySqlGrammar.php | | |____PostgresGrammar.php | | |____SQLiteGrammar.php | | |____SqlServerGrammar.php | |____JoinClause.php | |____JsonExpression.php | |____Processors | | |____MySqlProcessor.php | | |____PostgresProcessor.php | | |____Processor.php | | |____SQLiteProcessor.php | | |____SqlServerProcessor.php |____QueryException.php |____README.md |____Schema | |____Blueprint.php | |____Builder.php | |____Grammars | | |____ChangeColumn.php | | |____Grammar.php | | |____MySqlGrammar.php | | |____PostgresGrammar.php | | |____RenameColumn.php | | |____SQLiteGrammar.php | | |____SqlServerGrammar.php | |____MySqlBuilder.php | |____PostgresBuilder.php | |____SQLiteBuilder.php | |____SqlServerBuilder.php |____Seeder.php ```