Using Symfony Forms with Rich Domain Models

With the popularisation of DDD people started shifting from anemic models with only getters and setters to a rich model describing the state changes in specific methods. This way of designing models does not play well with Symfony forms. User provided input is inherently invalid while we want to maintain certain invariants in our domain model. A common approach to overcome these limitations is to create data transfer objects our forms are then bound to. This can lead to lots of mapping & glue code that might be cumbersome to write and maintain. But couldn’t we do better? In this talk we will discuss the different aspects of a rich domain model that makes it hard to use it in conjunction with the Form component. We will then look at the possibilities to hook into the data flow of the form handling and discover how we can modify it to interact seamlessly with our model.

Bundle: https://github.com/sensiolabs-de/rich-model-forms-bundle
Demo App: https://github.com/sensiolabs-de/rich-model-forms-demo

Transcript

1. @xabbuh && @el_stoffel
   

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2. @xabbuh && @el_stoffel
   Christopher Hertel
   Consultant & Trainer @ SensioLabs
   Symfony User Group Berlin
   Christian Flothmann
   Software Developer @ SensioLabs
   Symfony Core & Docs Member
   

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3. @xabbuh && @el_stoffel
   Our Use Case
   

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4. @xabbuh && @el_stoffel
   Simple Product CRUD
   

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5. @xabbuh && @el_stoffel
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6. @xabbuh && @el_stoffel
   Forms
   

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7. @xabbuh && @el_stoffel
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8. @xabbuh && @el_stoffel
   Domain
   

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9. @xabbuh && @el_stoffel
   Product
   Name
   Category
   Price
   Category
   Name
   Parent
   Price
   Amount
   Taxrate
   Currency
   Category
   

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10. @xabbuh && @el_stoffel
    Standard Forms
    1. Solution
    

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11. @xabbuh && @el_stoffel
    Implementation
    

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12. @xabbuh && @el_stoffel
    Controller src/Controller/ProductController.php
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    FormType
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    src/Form/ProductType.php
    

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    class Product
    {
    private $id;
    /**
    * @Assert\Length(min=3)
    */
    private $name;
    /**
    * @Assert\NotNull
    */
    private $category;
    /**
    * @Assert\GreaterThan(0)
    */
    private $priceAmount;
    /**
    * @Assert\GreaterThanOrEqual(0)
    */
    private $priceTax;
    /**
    * @Assert\Currency
    */
    private $priceCurrency;
    public function getId(): ?int
    {
    Model
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    src/Entity/Product.php
    

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    * @Assert\Currency
    */
    private $priceCurrency;
    public function getId(): ?int
    {
    return $this->id;
    }
    public function getName(): ?string
    {
    return $this->name;
    }
    public function setName(?string $name): void
    {
    $this->name = $name;
    }
    public function getCategory(): ?Category
    {
    return $this->category;
    }
    public function setCategory(?Category $category): void
    {
    $this->category = $category;
    }
    public function getPriceAmount(): ?int
    {
    return $this->priceAmount;
    }
    public function setPriceAmount(?int $priceAmount): void
    {
    $this->priceAmount = $priceAmount;
    }
    Model
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    src/Entity/Product.php
    

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16. @xabbuh && @el_stoffel
    Data Flow
    

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17. @xabbuh && @el_stoffel
    HTML Form
    POST /product HTTP/1.1
    Host: localhost:8000
    Connection: keep-alive
    Content-Length: 133
    Cache-Control: max-age=0
    [...]
    Accept-Language: en;q=0.9
    product[name]: rocket
    product[category]: 18
    product[priceAmount]: 0.59
    product[priceTax]: 7
    product[priceCurrency]: EUR
    HTTP Request
    Form Submit
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18. @xabbuh && @el_stoffel
    POST /product HTTP/1.1
    Host: localhost:8000
    Connection: keep-alive
    Content-Length: 133
    Cache-Control: max-age=0
    [...]
    Accept-Language: en;q=0.9
    product[name]: rocket
    product[category]: 18
    product[priceAmount]: 0.59
    product[priceTax]: 7
    product[priceCurrency]: EUR
    HTTP Request HttpFoundation
    Front Controller
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19. @xabbuh && @el_stoffel
    HttpFoundation Controller
    Controller
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20. @xabbuh && @el_stoffel
    HttpFoundation Controller
    Controller
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21. @xabbuh && @el_stoffel
    Controller FormType
    Request Handler
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22. @xabbuh && @el_stoffel
    Code
    

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23. @xabbuh && @el_stoffel
    Symfony
    Front Controller
    HttpFoundation
    Form
    Validator
    Glue Code
    Controller
    FormType
    Domain
    Product
    Category
    Price
    

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24. @xabbuh && @el_stoffel
    FormType Model
    HTTP
    Request
    Front Controller
    Controller
    Form
    Glue Code Domain
    Symfony
    Model
    

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25. @xabbuh && @el_stoffel
    Anemic Domain Model
    

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26. @xabbuh && @el_stoffel
    Anemic Domain Model
    focus on data
    structured
    easy to implement and to maintain
    contains little or no logic
    no guarantee to be valid or consistent
    

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27. @xabbuh && @el_stoffel
    Rich Domain Model
    

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28. @xabbuh && @el_stoffel
    Rich Domain Model
    combines data and logic
    valid by design
    easy to test
    defined state transitions
    

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29. @xabbuh && @el_stoffel
    Anemic vs. Rich Model
    

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30. @xabbuh && @el_stoffel
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31. @xabbuh && @el_stoffel
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32. @xabbuh && @el_stoffel
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38. @xabbuh && @el_stoffel
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39. @xabbuh && @el_stoffel
    "how not to agree about software design"
    - sp00m on stackoverflow -
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40. @xabbuh && @el_stoffel
    Anemic Models
    Prototyping
    Ease of use
    Easily generated
    Rich Models
    Clean Code
    Testability
    Truly OOP
    Your Choice!
    

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41. @xabbuh && @el_stoffel
    Let's use Rich Domain Models
    with Symfony Forms
    

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42. @xabbuh && @el_stoffel
    class Product
    {
    private $id;
    private $name;
    private $category;
    private $price;
    public function __construct(string $name, Category $category, Price $price)
    {
    $this->validateName($name);
    $this->name = $name;
    $this->category = $category;
    $this->price = $price;
    }
    public function getId(): int
    {
    return $this->id;
    }
    public function getName(): string
    {
    return $this->name;
    }
    public function rename(string $name): void
    {
    $this->validateName($name);
    Model src/Entity/Product.php
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43. @xabbuh && @el_stoffel
    public function getId(): int
    {
    return $this->id;
    }
    public function getName(): string
    {
    return $this->name;
    }
    public function rename(string $name): void
    {
    $this->validateName($name);
    $this->name = $name;
    }
    public function getCategory(): Category
    {
    return $this->category;
    }
    public function moveToCategory(Category $category): void
    {
    $this->category = $category;
    }
    public function getPrice(): Price
    {
    return $this->price;
    }
    public function costs(Price $price): void
    {
    $this->price = $price;
    }
    Model src/Entity/Product.php
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44. @xabbuh && @el_stoffel
    $this->name = $name;
    }
    public function getCategory(): Category
    {
    return $this->category;
    }
    public function moveToCategory(Category $category): void
    {
    $this->category = $category;
    }
    public function getPrice(): Price
    {
    return $this->price;
    }
    public function costs(Price $price): void
    {
    $this->price = $price;
    }
    private function validateName(string $name): void
    {
    if (strlen($name) < 3) {
    throw ProductException::invalidName($name);
    }
    }
    }
    Model src/Entity/Product.php
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45. @xabbuh && @el_stoffel
    Model src/Entity/Price.php
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46. @xabbuh && @el_stoffel
    Model src/Entity/Category.php
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47. @xabbuh && @el_stoffel
    @xabbuh && @el_stoffel
    

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48. @xabbuh && @el_stoffel
    2. Solution
    Easy: Data ransfer bject
    T O s
    

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49. @xabbuh && @el_stoffel
    Implementation
    

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50. @xabbuh && @el_stoffel
    final class Product
    {
    public $id;
    /**
    * @Assert\Length(min=3)
    */
    public $name;
    /**
    * @Assert\NotNull
    */
    public $category;
    /**
    * @Assert\GreaterThan(0)
    */
    public $priceAmount;
    /**
    * @Assert\GreaterThanOrEqual(0)
    */
    public $priceTax;
    /**
    * @Assert\Currency
    */
    public $priceCurrency;
    public static function fromEntity(ProductEntity $product = null): self
    DTO src/Form/DTO/Product.php
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51. @xabbuh && @el_stoffel
    /**
    * @Assert\Currency
    */
    public $priceCurrency;
    public static function fromEntity(ProductEntity $product = null): self
    {
    $self = new self();
    if (null === $product) {
    return $self;
    }
    $self->id = $product->getId();
    $self->name = $product->getName();
    $self->category = $product->getCategory();
    $self->priceAmount = $product->getPrice()->getAmount();
    $self->priceTax = $product->getPrice()->getTax();
    $self->priceCurrency = $product->getPrice()->getCurrency();
    return $self;
    }
    public function toEntity(ProductEntity $product = null): ProductEntity
    {
    $price = new Price((int) $this->priceAmount, $this->priceTax, $this-
    >priceCurrency);
    DTO src/Form/DTO/Product.php
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    $self->category = $product->getCategory();
    $self->priceAmount = $product->getPrice()->getAmount();
    $self->priceTax = $product->getPrice()->getTax();
    $self->priceCurrency = $product->getPrice()->getCurrency();
    return $self;
    }
    public function toEntity(ProductEntity $product = null): ProductEntity
    {
    $price = new Price((int) $this->priceAmount, $this->priceTax, $this->priceCurrency);
    if (null === $product) {
    return new ProductEntity($this->name, $this->category, $price);
    }
    if ($product->getName() !== $this->name) {
    $product->rename($this->name);
    }
    if ($product->getCategory() !== $this->category) {
    $product->moveToCategory($this->category);
    }
    if (!$price->equals($product->getPrice())) {
    $product->costs($price);
    }
    return $product;
    }
    }
    DTO src/Form/DTO/Product.php
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53. @xabbuh && @el_stoffel
    FormType src/Form/ProductType.php
    @xabbuh && @el_stoffel
    

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54. @xabbuh && @el_stoffel
    Controller src/Controller/ProductController.php
    @xabbuh && @el_stoffel
    

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55. @xabbuh && @el_stoffel
    Data Flow
    

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56. @xabbuh && @el_stoffel
    HTML Formular
    POST /product HTTP/1.1
    Host: localhost:8000
    Connection: keep-alive
    Content-Length: 133
    Cache-Control: max-age=0
    [...]
    Accept-Language: en;q=0.9
    product[name]: rocket
    product[category]: 18
    product[priceAmount]: 0.59
    product[priceTax]: 7
    product[priceCurrency]: EUR
    HTTP Request
    Form Submit
    @xabbuh && @el_stoffel
    

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57. @xabbuh && @el_stoffel
    POST /product HTTP/1.1
    Host: localhost:8000
    Connection: keep-alive
    Content-Length: 133
    Cache-Control: max-age=0
    [...]
    Accept-Language: en;q=0.9
    product[name]: rocket
    product[category]: 18
    product[priceAmount]: 0.59
    product[priceTax]: 7
    product[priceCurrency]: EUR
    HTTP Request HttpFoundation
    Front Controller
    @xabbuh && @el_stoffel
    

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58. @xabbuh && @el_stoffel
    HttpFoundation Controller
    Controller
    @xabbuh && @el_stoffel
    

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59. @xabbuh && @el_stoffel
    HttpFoundation Controller
    Controller
    @xabbuh && @el_stoffel
    

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60. @xabbuh && @el_stoffel
    Controller FormType
    Request Handler
    ProductDto
    ProductDto::
    @xabbuh && @el_stoffel
    

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61. @xabbuh && @el_stoffel
    HttpFoundation Controller
    Controller
    @xabbuh && @el_stoffel
    

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62. @xabbuh && @el_stoffel
    Code
    

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63. @xabbuh && @el_stoffel
    Symfony
    Front Controller
    HttpFoundation
    Form
    Validator
    Glue Code
    Controller
    FormType
    DTO
    Domain
    Product
    Category
    Price
    

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64. @xabbuh && @el_stoffel
    FormType
    HTTP
    Request
    Front Controller
    Controller
    Form
    Glue Code Domain
    Symfony
    DTO
    Model
    Model
    DTO
    

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65. @xabbuh && @el_stoffel
    DTO Solution
    enables us to use Rich Domain Models
    easy to implement and maintain
    additional Glue Code
    redundant validation rules
    

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66. @xabbuh && @el_stoffel
    Hard: DataMapper
    3. Solution
    

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67. @xabbuh && @el_stoffel
    Implementation
    

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68. @xabbuh && @el_stoffel
    Controller src/Controller/ProductController.php
    @xabbuh && @el_stoffel
    same as first solution
    

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69. @xabbuh && @el_stoffel
    FormType src/Form/ProductType.php
    @xabbuh && @el_stoffel
    

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70. @xabbuh && @el_stoffel
    FormType src/Form/ProductType.php
    @xabbuh && @el_stoffel
    

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71. @xabbuh && @el_stoffel
    FormType src/Form/ProductType.php
    @xabbuh && @el_stoffel
    

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72. @xabbuh && @el_stoffel
    FormType src/Form/ProductType.php
    @xabbuh && @el_stoffel
    

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73. @xabbuh && @el_stoffel
    Data Flow
    

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74. @xabbuh && @el_stoffel
    HTML Formular
    Form Submit
    POST /product HTTP/1.1
    Host: localhost:8000
    Connection: keep-alive
    Content-Length: 133
    Cache-Control: max-age=0
    [...]
    Accept-Language: en;q=0.9
    product[name]: rocket
    product[category]: 18
    product[price][amount]: 0.59
    product[price][tax]: 7
    product[price][currency]: EUR
    HTTP Request
    @xabbuh && @el_stoffel
    

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75. @xabbuh && @el_stoffel
    Front Controller
    POST /product HTTP/1.1
    Host: localhost:8000
    Connection: keep-alive
    Content-Length: 133
    Cache-Control: max-age=0
    [...]
    Accept-Language: en;q=0.9
    product[name]: rocket
    product[category]: 18
    product[price][amount]: 0.59
    product[price][tax]: 7
    product[price][currency]: EUR
    HTTP Request HttpFoundation
    @xabbuh && @el_stoffel
    

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76. @xabbuh && @el_stoffel
    HttpFoundation Controller
    Controller
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77. @xabbuh && @el_stoffel
    HttpFoundation Controller
    Controller
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78. @xabbuh && @el_stoffel
    Request Handler
    Controller FormType
    DataMapper
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79. @xabbuh && @el_stoffel
    Code
    

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80. @xabbuh && @el_stoffel
    Symfony
    Front Controller
    HttpFoundation
    Form
    Validator
    Glue Code
    Controller
    FormType
    DataMapper
    Domain
    Product
    Category
    Price
    

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81. @xabbuh && @el_stoffel
    Form
    Type
    Model
    HTTP
    Request
    Front Controller
    Controller
    Form
    Glue Code Domain
    Symfony
    Model
    Data
    Mapper
    Data
    Mapper
    

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82. @xabbuh && @el_stoffel
    DataMapper Solution
    enables us to use Rich Domain Models
    requires advanced knowledge about Forms
    additional Glue Code
    hard to test
    

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83. @xabbuh && @el_stoffel
    Still not satisfied?
    

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84. @xabbuh && @el_stoffel
    We feel you …
    

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85. @xabbuh && @el_stoffel
    Introducing …
    

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86. @xabbuh && @el_stoffel
    New: RichModelFormsBundle
    4. Solution
    

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87. @xabbuh && @el_stoffel
    sensiolabs-de/rich-model-forms-bundle
    Disclaimer: Still Experimental
    

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88. @xabbuh && @el_stoffel
    Installation
    

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89. @xabbuh && @el_stoffel
    composer require \
    sensiolabs-de/rich-model-forms-bundle
    

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90. @xabbuh && @el_stoffel
    Features
    

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91. @xabbuh && @el_stoffel
    Different read/write property paths
    

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92. @xabbuh && @el_stoffel
    Different read/write property paths
    

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93. @xabbuh && @el_stoffel
    Exception Handling
    

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94. @xabbuh && @el_stoffel
    Exception Handling
    

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95. @xabbuh && @el_stoffel
    Mandatory Constructor Arguments
    

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96. @xabbuh && @el_stoffel
    Mandatory Constructor Arguments
    

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97. @xabbuh && @el_stoffel
    Immutable Value Object
    

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98. @xabbuh && @el_stoffel
    Immutable Value Object
    

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99. @xabbuh && @el_stoffel
    Implementation
    

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100. @xabbuh && @el_stoffel
     Controller src/Controller/ProductController.php
     still same as first solution
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101. @xabbuh && @el_stoffel
     FormType src/Form/ProductType.php
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102. @xabbuh && @el_stoffel
     FormType src/Form/ProductType.php
     @xabbuh && @el_stoffel
     

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103. @xabbuh && @el_stoffel
     Data Flow
     

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104. @xabbuh && @el_stoffel
     HTML Formular
     Form Submit
     POST /product HTTP/1.1
     Host: localhost:8000
     Connection: keep-alive
     Content-Length: 133
     Cache-Control: max-age=0
     [...]
     Accept-Language: en;q=0.9
     product[name]: rocket
     product[category]: 18
     product[price][amount]: 0.59
     product[price][tax]: 7
     product[price][currency]: EUR
     HTTP Request
     

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105. @xabbuh && @el_stoffel
     POST /product HTTP/1.1
     Host: localhost:8000
     Connection: keep-alive
     Content-Length: 133
     Cache-Control: max-age=0
     [...]
     Accept-Language: en;q=0.9
     product[name]: rocket
     product[category]: 18
     product[price][amount]: 0.59
     product[price][tax]: 7
     product[price][currency]: EUR
     HTTP Request HttpFoundation
     Front Controller
     

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106. @xabbuh && @el_stoffel
     HttpFoundation Controller
     Controller
     @xabbuh && @el_stoffel
     

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107. @xabbuh && @el_stoffel
     HttpFoundation Controller
     Controller
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108. @xabbuh && @el_stoffel
     Request Handler
     Controller FormType
     RichModelFormsBundle
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109. @xabbuh && @el_stoffel
     Code
     

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110. @xabbuh && @el_stoffel
     Symfony
     Front Controller
     HttpFoundation
     Form
     New Bundle
     Glue Code
     Controller
     FormType
     Domain
     Model
     

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111. @xabbuh && @el_stoffel
     FormType Model
     HTTP
     Request
     Front Controller
     Controller
     Form
     Glue Code Domain
     Symfony
     Model
     

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112. @xabbuh && @el_stoffel
     RichModelFormsBundle to the rescue!
     generalizes the previous approach
     additional form config options
     tailored for rich model form needs
     released, but still in development
     

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113. @xabbuh && @el_stoffel
     Final Disclaimer
     not feature complete
     covers common use cases we discovered
     needs input for more use cases
     no, not yet in production
     

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114. @xabbuh && @el_stoffel
     Your turn!
     Help us make it stable!
     

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115. @xabbuh && @el_stoffel
     DTOs New Bundle
     DataMapper
     hard to implement
     hard to test
     additional glue code
     easy to implement
     duplicated validation
     additional glue code
     no glue code needed
     experimental
     future core feature?
     Using Symfony Forms with Rich Domain Models
     

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116. @xabbuh && @el_stoffel
     Thank you! Questions?
     

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