Table of Contents for
Magento 2 Development Quick Start Guide

Version ebook / Retour

Cover image for bash Cookbook, 2nd Edition Magento 2 Development Quick Start Guide by Branko Ajzele Published by Packt Publishing, 2018
  1. Magento 2 Development Quick Start Guide
  2. Title Page
  3. Copyright and Credits
  4. Magento 2 Development Quick Start Guide
  5. Packt Upsell
  6. Why subscribe?
  7. Packt.com
  8. Contributors
  9. About the author
  10. About the reviewer
  11. Packt is searching for authors like you
  12. Table of Contents
  13. Preface
  14. Who this book is for
  15. What this book covers
  16. To get the most out of this book
  17. Download the example code files
  18. Code in Action
  19. Conventions used
  20. Get in touch
  21. Reviews
  22. Understanding the Magento Architecture
  23. Technical requirements
  24. Installing Magento
  25. Modes
  26. Areas
  27. Request flow processing
  28. Modules
  29. Creating the minimal module
  30. Cache
  31. Dependency injection
  32. Argument injection
  33. Virtual types
  34. Proxies
  35. Factories
  36. Plugins
  37. The before plugin
  38. The around plugin
  39. The after plugin
  40. Events and observers
  41. Console commands
  42. Cron jobs
  43. Summary
  44. Working with Entities
  45. Technical requirements
  46. Understanding types of models
  47. Creating a simple model
  48. Methods worth memorizing
  49. Working with setup scripts
  50. The InstallSchema script
  51. The UpgradeSchema script
  52. The Recurring script
  53. The InstallData script
  54. The UpgradeData script
  55. The RecurringData script
  56. Extending entities
  57. Creating extension attributes
  58. Summary
  59. Understanding Web APIs
  60. Technical requirements
  61. Types of users
  62. Types of authentication
  63. Types of APIs
  64. Using existing web APIs
  65. Creating custom web APIs
  66. Understanding search criteria
  67. Summary
  68. Building and Distributing Extensions
  69. Technical requirements
  70. Building a shipping extension
  71. Distributing via GitHub
  72. Distributing via Packagist
  73. Summary
  74. Developing for Admin
  75. Technical requirements
  76. Using the listing component
  77. Using the form component
  78. Summary
  79. Developing for Storefront
  80. Technical requirements
  81. Setting up the playground
  82. Calling and initializing JS components
  83. Meet RequireJS
  84. Replacing jQuery widget components
  85. Extending jQuery widget components
  86. Creating jQuery widgets components
  87. Creating UI/KnockoutJS components
  88. Extending UI/KnockoutJS components
  89. Summary
  90. Customizing Catalog Behavior
  91. Technical requirements
  92. Creating the size guide
  93. Creating the same day delivery
  94. Flagging new products
  95. Summary
  96. Customizing Checkout Experiences
  97. Technical requirements
  98. Passing data to the checkout
  99. Adding order notes to the checkout
  100. Summary
  101. Customizing Customer Interactions
  102. Technical requirements
  103. Understanding the section mechanism
  104. Adding contact preferences to customer accounts
  105. Adding contact preferences to the checkout
  106. Summary
  107. Other Books You May Enjoy
  108. Leave a review - let other readers know what you think

Virtual types

Virtual types are a very neat feature of Magento that allow us to change the arguments of a specific injectable dependency and thus change the behavior of a particular class type.

The <MAGENTO_DIR>/module-checkout/etc/di.xml file provides a simple example of virtualType and its usage:

<virtualType name="Magento\Checkout\Model\Session\Storage" type="Magento\Framework\Session\Storage">
    <arguments>
        <argument name="namespace" xsi:type="string">checkout</argument>
    </arguments>
</virtualType>
<type name="Magento\Checkout\Model\Session">
    <arguments>
        <argument name="storage" xsi:type="object">Magento\Checkout\Model\Session\Storage</argument>
    </arguments>
</type>

The virtualType here (virtually) extends Magento\Framework\Session\Storage by rewriting its constructor's $namespace = 'default' argument to $namespace = 'checkout'. However, this change does not kick in on its own, as the Magento\Checkout\Model\Session\Storage virtual type must be used first. It is used in this case, via a type definition, where the storage argument is replaced entirely by the virtual type.

Most of the virtualType name attributes across Magento take the form of a non-existing fully qualified class name, though this can be any character combination that's allowed in PHP array keys.

By doing a lookup for the <virtualType string across the entire <MAGENTO_DIR> directory's di.xml files, we can see that Magento uses hundreds of virtual types across the majority of its modules.

A more complex example of virtual type usage can be found under the Magento_LayeredNavigation module.

The <MAGENTO_DIR>/module-layered-navigation/etc/frontend/di.xml file defines two virtual types, as follows:

<virtualType name="Magento\LayeredNavigation\Block\Navigation\Category" type="Magento\LayeredNavigation\Block\Navigation">
    <arguments>
        <argument name="filterList" xsi:type="object">categoryFilterList</argument>
    </arguments>
</virtualType>

<virtualType name="Magento\LayeredNavigation\Block\Navigation\Search" type="Magento\LayeredNavigation\Block\Navigation">
    <arguments>
        <argument name="filterList" xsi:type="object">searchFilterList</argument>
    </arguments>
</virtualType>

Here, we have two virtual types defined, each changing the filterList argument of the Magento\LayeredNavigation\Block\Navigation class. categoryFilterList and searchFilterList are the names of two other virtual types that are defined in <MAGENTO_DIR>/module-catalog-search/etc/di.xml, as visible here: https://github.com/magento/magento2/blob/2.2/app/code/Magento/CatalogSearch/etc/di.xml.

The Magento\LayeredNavigation\Block\Navigation\Category and Magento\LayeredNavigation\Block\Navigation\Search virtual types are then used in layout files for block definition, as follows:

<!-- view/frontend/layout/catalog_category_view_type_layered.xml -->
<referenceContainer name="sidebar.main">
    <block class="Magento\LayeredNavigation\Block\Navigation\Category" ...
</referenceContainer>

<!-- view/frontend/layout/catalogsearch_result_index.xml -->
<referenceContainer name="sidebar.main">
    <block class="Magento\LayeredNavigation\Block\Navigation\Search" ...
</referenceContainer>

What this effectively does is tell Magento that, for the category view page and search page, use the virtual type for class, thus instructing it to go through all the argument changes specified in the virtual type.

This is an interesting example as it reveals the potential complexity of using virtual types. Basically, we have one virtual type (Magento\LayeredNavigation\Block\Navigation\Search) changing the single filterList argument of a real type (Magento\LayeredNavigation\Block\Navigation) with another virtual type (categoryFilterList). Likewise, we just learned how the class property of the block element is capable of not just accepting the fully qualified class name, but the virtualType name as well.