問(wèn)題描述

我不希望有人說(shuō)你不應(yīng)該重新發(fā)明輪子，使用開(kāi)源 ORM"；我有一個(gè)即時(shí)需求，無(wú)法切換.

我正在做一些支持緩存的 ORM.即使不支持緩存，我還是需要這個(gè)功能，以了解何時(shí)將對(duì)象寫(xiě)入存儲(chǔ).模式是 DataMapper.

這是我的方法:

• 我想避免運(yùn)行時(shí)內(nèi)省(即猜測(cè)屬性).
• 我不想使用 CLI 代碼生成器來(lái)生成 getter 和 setter(實(shí)際上我使用的是 NetBeans，使用 ALT+INSERT).
• 我希望模型最接近 POPO(普通的舊 PHP 對(duì)象).我的意思是:私有屬性，每個(gè)屬性的硬編碼"getter 和 setter.

我有一個(gè)名為 AbstractModel 的抽象類(lèi)，所有模型都繼承了它.它有一個(gè)名為 isDirty() 的公共方法，帶有一個(gè)名為 is_dirty 的私有屬性(如果需要，也可以被保護(hù)).它必須返回 true 或 false，具體取決于對(duì)象數(shù)據(jù)自加載后是否發(fā)生更改.

問(wèn)題是:有沒(méi)有辦法在每個(gè) setter $this->is_dirty = true<中不用編碼就提升內(nèi)部標(biāo)志 "is_dirty"/代碼>?我的意思是:大多數(shù)情況下，我希望將 setter 設(shè)置為 $this->attr = $value，除非業(yè)務(wù)邏輯需要更改代碼.

其他限制是我不能依賴(lài) __set 因?yàn)樵诰唧w模型類(lèi)中屬性已經(jīng)作為私有存在，所以 __set 永遠(yuǎn)不會(huì)在 setter 上調(diào)用.>

有什么想法嗎?接受來(lái)自其他 ORM 的代碼示例.

我的一個(gè)想法是修改 NetBeans setter 模板，但我認(rèn)為應(yīng)該有一種不依賴(lài)于 IDE 的方法.

我的另一個(gè)想法是創(chuàng)建 setter，然后用下劃線(xiàn)或其他東西更改私有屬性的名稱(chēng).這樣 setter 會(huì)調(diào)用 __set 并在那里有一些代碼來(lái)處理 "is_dirty" 標(biāo)志，但這有點(diǎn)打破了 POPO 概念，而且很丑陋.

_{注意！
我對(duì)這個(gè)主題的看法在過(guò)去一個(gè)月有所改變.雖然答案 where 仍然有效，但在處理大型對(duì)象圖時(shí)，我建議改用工作單元模式.您可以在這個(gè)答案}

中找到對(duì)其的簡(jiǎn)要說(shuō)明

我有點(diǎn)困惑 what-you-call-Model 與 ORM 的關(guān)系.這有點(diǎn)令人困惑.特別是因?yàn)樵?MVC 中 Model 是一個(gè)層(至少，我是這么理解的，而你的模型"似乎更像是域?qū)ο?.

我將假設(shè)您擁有的是如下所示的代碼:

 $model = new SomeModel;$mapper = $ormFactory->build('something');$model->setId(1337);$mapper->pull( $model );$model->setPayload('cogito ergo sum');$mapper->push( $model );

而且，我將假設(shè) what-you-call-Model 有兩個(gè)方法，設(shè)計(jì)器供數(shù)據(jù)映射器使用:getParameters() 和 setParameters().并且您在映射器存儲(chǔ) what-you-call-Model 的狀態(tài)并調(diào)用 cleanState() 之前調(diào)用 isDirty() - 當(dāng)映射器拉數(shù)據(jù)到what-you-call-Model.

_{順便說(shuō)一句，如果您有更好的建議從數(shù)據(jù)映射器中獲取值而不是 setParameters() 和 getParameters()，請(qǐng)分享，因?yàn)槲乙恢痹谂ο氤龈玫臇|西.在我看來(lái)，這就像封裝泄漏.}

這將使數(shù)據(jù)映射器方法看起來(lái)像:

 公共函數(shù) pull( 參數(shù)化 $object ){如果 ( !$object->isDirty() ){//沒(méi)有在干凈的對(duì)象上設(shè)置任何條件//或者自上次拉取后值沒(méi)有改變返回假；//或者可能拋出異常}$data =//執(zhí)行從存儲(chǔ)中讀取信息的操作$object->setParameters($data);$object->cleanState();返回 $true;//或省略，如果替代作為例外}公共靜態(tài)函數(shù)推送(參數(shù)化 $object ){如果 ( !$object->isDirty() ){//沒(méi)有什么可以保存的，走開(kāi)返回假；//或者可能拋出異常}$data = $object->getParameters();//將值保存在存儲(chǔ)中$object->cleanState();返回 $true;//或省略，如果替代作為例外}

<塊引用>

_{在代碼片段中 Parametrized 是接口的名稱(chēng)，該對(duì)象應(yīng)該實(shí)現(xiàn).在這種情況下，方法 getParameters() 和 setParameters().它有一個(gè)如此奇怪的名字，因?yàn)樵?OOP 中，implements 詞的意思是 has-abilities-of ，而 extends 表示 is-a.}

到這部分為止，您應(yīng)該已經(jīng)擁有所有類(lèi)似的東西...

現(xiàn)在這里是 isDirty() 和 cleanState() 方法應(yīng)該做的:

 公共函數(shù) cleanState(){$this->is_dirty = false;$temp = get_object_vars($this);取消設(shè)置( $temp['variableChecksum'] );//校驗(yàn)和不應(yīng)該是它自身的一部分$this->variableChecksum = md5( serialize( $temp ) );}公共函數(shù) isDirty(){if ( $this->is_dirty === true ){返回真；}$previous = $this->variableChecksum;$temp = get_object_vars($this);取消設(shè)置( $temp['variableChecksum'] );//校驗(yàn)和不應(yīng)該是它自身的一部分$this->variableChecksum = md5( serialize( $temp ) );返回 $previous !== $this->variableChecksum;}

I don't want anyone saying "you should not reinvent the wheel, use an open source ORM"; I have an immediate requirement and cannot switch.

I'm doing a little ORM, that supports caching. Even not supporting caching, I would need this feature anyways, to know when to write an object to storage or not. The pattern is DataMapper.

Here is my approach:

• I want to avoid runtime introspection (i.e. guessing attributes).
• I don't want to use a CLI code generator to generate getters and setters (really I use the NetBeans one, using ALT+INSERT).
• I want the model to be the closest to a POPO (plain old PHP object). I mean: private attributes, "hardcoded" getters and setters for each attribute.

I have an Abstract class called AbstractModel that all the models inherit. It has a public method called isDirty() with a private (can be protected too, if needed) attribute called is_dirty. It must return true or false depending if there is a change on the object data or not since it was loaded.

The issue is: is there a way to raise the internal flag "is_dirty" without coding in each setter $this->is_dirty = true? I mean: I want to have the setters as $this->attr = $value most of the time, except a code change is needed for business logic.

Other limitation is that I cannot rely on __set because on the concrete model class the attributes already exists as private, so __set is never called on the setters.

Any ideas? Code examples from others ORMs are accepted.

One of my ideas was to modify the NetBeans setters template, but I think there should be a way of doing this without relying on the IDE.

Another thought I had was creating the setters and then change the private attribute's name with an underscore or something. This way the setter would call to __set and have some code there to deal with the "is_dirty" flag, but this breaks the POPO concept a little, and it's ugly.

_{Attention!
My opinion on the subject has somewhat changed in the past month. While the answer where is still valid, when dealing with large object graphs, I would recommend using Unit-of-Work pattern instead. You can find a brief explanation of it in this answer}

I'm kinda confused how what-you-call-Model is related to ORM. It's kinda confusing. Especially since in MVC the Model is a layer (at least, thats how I understand it, and your "Models" seem to be more like Domain Objects).

I will assume that what you have is a code that looks like this:

  $model = new SomeModel;
  $mapper = $ormFactory->build('something');

  $model->setId( 1337 );
  $mapper->pull( $model );

  $model->setPayload('cogito ergo sum');

  $mapper->push( $model );

And, i will assume that what-you-call-Model has two methods, designer to be used by data mappers: getParameters() and setParameters(). And that you call isDirty() before mapper stores what-you-call-Model's state and call cleanState() - when mapper pull data into what-you-call-Model.

_{BTW, if you have a better suggestion for getting values from-and-to data mappers instead of setParameters() and getParameters(), please share, because I have been struggling to come up with something better. This seems to me like encapsulation leak.}

This would make the data mapper methods look like:

  public function pull( Parametrized $object )
  {
      if ( !$object->isDirty() )
      {
          // there were NO conditions set on clean object
          // or the values have not changed since last pull
          return false; // or maybe throw exception
      }

      $data = // do stuff which read information from storage

      $object->setParameters( $data );
      $object->cleanState();

      return $true; // or leave out ,if alternative as exception
  }

  public static function push( Parametrized $object )
  {
      if ( !$object->isDirty() )
      {
          // there is nothing to save, go away
          return false; // or maybe throw exception
      }

      $data = $object->getParameters();
      // save values in storage
      $object->cleanState();

      return $true; // or leave out ,if alternative as exception
  }

_{In the code snippet Parametrized is a name of interface, which object should be implementing. In this case the methods getParameters() and setParameters(). And it has such a strange name, because in OOP, the implements word means has-abilities-of , while the extends means is-a.}

Up to this part you should already have everything similar...

Now here is what the isDirty() and cleanState() methods should do:

  public function cleanState()
  {
      $this->is_dirty = false;
      $temp = get_object_vars($this);
      unset( $temp['variableChecksum'] );
      // checksum should not be part of itself
      $this->variableChecksum = md5( serialize( $temp ) );
  }

  public function isDirty()
  {
      if ( $this->is_dirty === true )
      {
          return true;
      }

      $previous = $this->variableChecksum;

      $temp = get_object_vars($this);
      unset( $temp['variableChecksum'] );
      // checksum should not be part of itself
      $this->variableChecksum = md5( serialize( $temp ) );

      return $previous !== $this->variableChecksum;
  }

這篇關(guān)于在 ORM 模型中處理臟狀態(tài)的最佳方法的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，也希望大家多多支持html5模板網(wǎng)！