新創公司與軟體架構

by 尤川豪

新創公司的挑戰?

程式碼很難改的原因

  • Entity(Model)太胖
  • Controller太髒
  • 沒有人測系統

Entity太胖

  • Entity
  • Presenter
  • Repository
  • Form
  • Service
  • Operation
  • Package

軟體測試:鏡射結構

Controller太髒

沒有人測系統

Entity太胖

  • Entity
  • Presenter
  • Repository
  • Form

Entity

Presenter

把日期、金額、名稱之類的呈現(presentation)邏輯抽離出來!

問題:presentation易讓entity過胖

class Article
{
    public function getDate(){/*...*/}

    public function getTaiwaneseDateTime(){/*...*/}

    public function getWesternDateTime(){/*...*/}

    public function getTaiwaneseDate(){/*...*/}

    public function getWesternDate(){/*...*/}
}

step 1. 抽出presentation logic

class ArticlePresenter
{
    protected $article;

    public function __construct(Article $article)
    {
        $this->article = $article;
    }

    public function getTaiwaneseDateTime(){
        return date('Y-m-d', $this->article->created_at);
    }

    public function getWesternDateTime(){/*...*/}
    public function getTaiwaneseDate(){/*...*/}
    public function getWesternDate(){/*...*/}
}

step 2. 從entity連到presenter

class Article
{
    public function present()
    {
        return new ArticlePresenter($this);
    }
}

step 3. 

$article->present()->getTaiwaneseDate();

Repository

把查詢(query)的邏輯,也就是取得entity的各種方式抽離出來!

step 1. 抽出query logic

class UserRepository
{
    public function getPopularWomen()
    {
        return User::where('votes', '>', 100)
            ->whereGender('W')
            ->orderBy('created_at')
            ->get();
    }

    public function getActiveUsers(){}
    public function getPaidUsers(){}
}

step 2.

$repository = new UserRepository();

$users = $repository->getPopularWomen();

Form

把參數驗證(validation)的邏輯(例如字串長度、日期、金額大小)抽離出來!

問題:參數驗證的code,放哪好呢

$validation = Validator::make(
    array(
        'title' => $title,
        'content' => $content,
    ),
    array(
        'title' => array( 'required', 'alpha_dash' ),
        'content' => array( 'required' ),
    )
);

return $validation->passes();

step 1. 封進Form

class ArticleForm
{
    protected $validationRules = [
        'title' =>  array( 'required', 'alpha_dash' ),
        'content' => array( 'required' )
    ];
    protected $validator;
    public function isValid($input)
    {
        $this->validator = Validator::make($input, $this->validationRules);
        return $this->validator->passes();
    }    
    public function getErrors()
    {
        return $this->validator->errors();
    }

}

step 2.

$form = new ArticleForm();
 
if ( ! $form->isValid(Input::all()) ){
    return Redirect::back()->with( [ 'errors' => $form->getErrors() ] );    
}

// Passed the validation. 
// Create the article.

Entity太胖

  • Entity
  • Presenter
  • Repository
  • Form
  • Service
  • Operation
  • Package

軟體測試:鏡射結構

Controller太髒

沒有人測系統

Entity太胖、Controller太髒

  • Service
  • Operation
  • Package

Service

  1. 牽扯到外部行為
  2. controller內像又不像的商業邏輯
  3. 牽扯到多種entity

#1 牽扯到外部行為

  • 跑測試時,不想觸發外部行為
    (送email、透過網路呼叫第三方API...etc)
  • 應用constructor injection
  • 測試時,做mocks傳進去

範例:過程中,呼叫Google Drive備份

class TranslatorAssign
{
    protected $googleDrive;

    public function __construct($googleDrive)
    {
        $this->googleDrive = $googleDrive;
    }

    public function execute($user, $document)
    {
        $user->doSomething();

        $this->googleDrive->backup($document->file_id);
    }

}

step 1. 封成service

step 2. 跑測試

//寫一個有backup方法的假類別GoogleDriveMock
$service = new TranslatorAssign(new GoogleDriveMock());

$service->execute($user, $document);

$this->assertEquals(Document::ASSIGNED_STATUS, $document->status);

/* 用test framework支援的mocks也可以
    $stub = $this->getMockBuilder('GoogleDrive')
                 ->getMock();    

    $stub->method('backup')
         ->willReturn('foo');

    $service = new TranslatorAssign($stub);
*/

step 3.

$service = new TranslatorAssign(new GoogleDrive());

$service->execute($user, $document);

//Return successful page

#2 controller內
像又不像的商業邏輯

  • 感覺封不封進service,都可以嗎?
  • 想測試就封

範例:controller內,
單純的條件判斷,該封嗎?

 

$document = Document::find(Input::get('id'));

if(Input::get('role') == 'translator'){
    $document->doSomethingForTranslator();
    $document->doAnotherThingForTranslator();
}else if(Input::get('role') == 'editor'){
    $document->doSomethingForEditor();
    $document->doAnotherThingForEditor();
}

//Return successful page

step 1. 封成service

class GetAccessPermission
{
    //有想避開的dependency,就用constructor injection
    public function __construct(/*...*/)
    {
        //...
    }
    public function execute($document, $role)
    {
        if($role == 'translator'){
            $document->doSomethingForTranslator();
            $document->doAnotherThingForTranslator();
        }else if($role == 'editor'){
            $document->doSomethingForEditor();
            $document->doAnotherThingForEditor();
        }
    }
}

step 2. 跑測試

$service = new GetAccessPermission();

$service->execute($document, 'translator');

$this->assertTrue($document->has_translator);

$this->assertTrue($document->blah_blah);

step 3.

$document = Document::find(Input::get('id'));

$service = new GetAccessPermission();

$service->execute($document, Input::get('role'));

//Return successful page

#3 牽扯到多種entity

  • 如果某段code放進哪種entity都有點怪的話...
  • 索性獨立成service

範例:結帳牽扯到
User, Order, Product

class CheckoutBill
{

    public function execute($user, $order, $product)
    {
        //...
    }

}

Operation

  1. 發現某些service必須連續執行
  2. feature幾乎可以獨立開專案

#1 發現某些service
必須連續執行

  • 總是連續執行某幾個service,發現各自幾乎不獨立
  • 改寫成operation,用Facade Pattern封裝
  • 整個operation都透過facade對外溝通

範例:計算專案金額、
促銷價、交件日期

$calcDueDate = new CalcDueDate();

$calcPrice = new CalcPrice();

$calcDiscount = new CalcDiscount();

問題:好幾個地方duplicate

$calcDueDate->execute($order);

$calcPrice->execute($order);

$calcDiscount->execute($order);

step 1. Facade Pattern封裝

class QuotationManager
{
    protected $calcDueDate;
    protected $calcPrice;
    protected $calcDiscount;
    public __construct()
    {
        $this->calcDueDate = new CalcDueDate();        
        $this->calcPrice = new CalcPrice();        
        $this->calcDiscount = new CalcDiscount();
    }
    public function execute($order)
    {    
        $this->calcDueDate($order);        
        $this->calcPrice($order);        
        $this->calcDiscount($order);
    }
}

step 2.

$quotation = new QuotationManager();

$quotation->execute($order);

#2 feature幾乎
可以獨立開專案

  • 即將開發的功能幾乎獨立於原本的專案之外
  • 甚至可以放entity進去
  • 用Facade Pattern封裝。盡量以此對外溝通

範例:幾乎獨立的翻譯輔助工具

/MyApp
    /GlossarySystem
        /Manager.php
        /Analyzer.php
        /Generator.php
        /Parser.php
        /Splitter.php
        /Entity
            /Text.php
            /Segment.php

Package

把其他公司也能使用、

概念上獨立於當前專案的程式碼抽離出來!

/MyApp
    /...
    /...
/Howtomakeaturn(Github帳號)
    /MyPackage1
        /...
    /MyPackage2
        /...
    /MyPackage3
        /...

Entity太胖

  • Entity
  • Presenter
  • Repository
  • Form
  • Service
  • Operation
  • Package

軟體測試:鏡射結構

Controller太髒

沒有人測系統

軟體測試:鏡射結構

tests的檔案結構,與App核心一模一樣

/MyApp
    /Order
        /Order.php
        /OrderRepository.php
    /Product
        /Product.php
        /ProductPresenter.php
    /Service
        /TranslatorAssign.php
        /GetAccessPermission.php
        /CheckoutBill.php
    /...
tests/MyApp
    /Order
        /OrderTest.php
        /OrderRepositoryTest.php
    /Product
        /ProductTest.php
        /ProductPresenterTest.php
    /Service
        /TranslatorAssignTest.php
        /GetAccessPermissionTest.php
        /CheckoutBillTest.php
    /...

tests的檔案結構,

與App核心一模一樣

  • 設計方便、開發速度快
  • 不細分測試種類(unit tests/integration tests...etc)

Entity太胖

  • Entity
  • Presenter
  • Repository
  • Form
  • Service
  • Operation
  • Package

軟體測試:鏡射結構

Controller太髒

沒有人測系統

檔案結構範例

延伸閱讀

謝謝大家<( _ _ )>

新創公司與軟體架構

By howtomakeaturn

新創公司與軟體架構

新創公司需要快速開發程式來探索商業模式,同時,程式的需求又長時間保持在模糊狀態。 在追求開發速度之外,還需要兼顧程式的彈性。 如何設計軟體架構來滿足這種需求呢?

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