php学习Eloquent修改器源码示例解析_Php

引言

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

参考