Modernizing Legacy Code Step by Step

We’ll be taking a real PHP 5.2 codebase and migrating it to the latest and greatest PHP version. We’ll cover refactoring, adding components to handle routing, database access, as well as converting our HTML output to views. We’ll step through the entire process to demonstrate a repeatable solution for modernizing your legacy application!

Transcript

1. Modernizing Legacy
   Code Step By Step
   Joe Ferguson
   November 15th 2018
   

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2. Who Am I?
   Joe Ferguson
   PHP Developer
   PHP Architect @ Ministry Brands
   Twitter: @JoePFerguson
   OSMI Board Member
   Drone Racing Pilot
   

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3. For Further Reading
   leanpub.com/mlaphp
   leanpub.com/minimumviabletests
   

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4. Legacy Applications
   

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5. “There are no solutions,
   only trade offs”
   - Joe Ferguson
   - Paul M. Jones
   - Thomas Sowell
   

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6. Taking stock of what we’re
   working with
   

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10. Initial Project Overview
    Is there a framework?
    Is there a coding standard?
    Is there any autoloading?
    How are dependencies behind handled?
    Is there an ORM or how is the database being utilized?
    Is there a development environment?
    

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11. Is there a framework?
    

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12. Is there a framework?
    

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13. Is there a coding standard?
    

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15. Is there a coding standard?
    

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16. No Standard? No problem!
    

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17. Is there any autoloading?
    

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19. Is there any autoloading?
    

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20. There is a PSR for that…
    

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21. How are dependencies handled?
    

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23. Is there an ORM or how is the
    database being utilized?
    

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25. Tools to help
    

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26. PHP Coding Standards Fixer
    http://cs.sensiolabs.org/
    

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27. PHP Coding Standards Fixer
    php-cs-fixer fix app --dry-run
    

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28. PHP Mess Detector
    https://phpmd.org
    

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29. PHP Mess Detector
    https://phpmd.org
    $ phpmd app html cleancode --reportfile report.html
    

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30. Warning about Automating
    Code Changes
    

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31. Composer
    https://getcomposer.org/doc/01-basic-usage.md
    

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32. Triage
    Address any critical things found
    PHP Short Tags!
    PHP version issues
    Current server is 5.2 lets test 7.2
    Fixing critical vulnerabilities
    

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33. Get into Git!
    

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34. Get into Git!
    

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35. “We should just rewrite the app”
    

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36. "This would be so much easier in
    framework _____________”
    

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37. Why not rewrite?
    Progress halts entirely
    Business logic is rarely reused
    Most of the time is getting back to
    current functionality
    

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38. Why you should refactor
    Progress continues
    Business logic reused
    Modernizing functionality instead
    of recreating
    

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39. Existing Tests
    This is great!
    Review the tests to get an idea of coverage
    Passing tests become your control for any upcoming changes
    Confidence++
    

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40. No Existing Tests
    Not the end of the world!
    Inspect the code base, was it written to be easily testable?
    Could you easily mock dependencies?
    

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41. Untestable Code
    Not all code is testable
    If you can’t easily unit test the code base, consider alternatives
    Functional testing and Acceptance testing are valid options
    

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42. Acceptance Testing
    NOT a replacement for Unit Testing
    Test large parts of your application at a time
    Can be harder to pinpoint error location
    Gives large code coverage in short amount of time
    

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50. Digging into the Code
    Code Consolidation
    

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51. Code Consolidation
    

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52. Code Consolidation
    

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53. _config_vars.php
    

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54. _db_connect.php
    

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55. composer require vlucas/phpdotenv
    

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57. Database Class
    

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58. Progress
    

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59. header.php
    

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60. Digging into the Code
    Code Consolidation
    Replace globals with DI
    

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64. Digging into the Code
    Code Consolidation
    Replace globals with Dependency Injection
    Write tests
    

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68. Digging into the Code
    Code Consolidation
    Replace globals with Dependency Injection
    Write tests
    Extract SQL (to ORM or other)
    

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69. Digging into the Code
    Code Consolidation
    Replace globals with Dependency Injection
    Write tests
    Extract SQL (to ORM or other)
    Extract Business Logic (To domain logic)
    

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72. _functions.php
    

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73. Weather Class
    

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74. Refactoring index.php
    

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75. header.php
    

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76. Digging into the Code
    Code Consolidation
    Replace globals with Dependency Injection
    Write tests
    Extract SQL (to ORM or other)
    Extract Business Logic (To domain logic)
    Extract Presentation Logic to Views (Twig, Blade, etc)
    

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77. Digging into the Code
    Code Consolidation
    Replace globals with Dependency Injection
    Write tests
    Extract SQL (to ORM or other)
    Extract Business Logic (To domain logic)
    Extract Presentation Logic to Views (Twig, Blade, etc)
    Extract Action Logic (To Controllers)
    

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78. Digging into the Code
    Code Consolidation
    Replace globals with Dependency Injection
    Write tests
    Extract SQL (to ORM or other)
    Extract Business Logic (To domain logic)
    Extract Presentation Logic to Views (Twig, Blade, etc)
    Extract Action Logic (To Controllers)
    Write (more) tests
    

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79. Resources / Q & A
    Modernizing Legacy Applications In PHP - Paul M. Jones
    https://leanpub.com/mlaphp
    Minimum Viable Tests - Chris Hartjes
    https://leanpub.com/minimumviabletests
    Code Style https://github.com/FriendsOfPHP/PHP-CS-Fixer, http://editorconfig.org
    php mess detector https://phpmd.org
    Autoloading PSR-4 https://getcomposer.org/doc/01-basic-usage.md
    ORMs http://www.doctrine-project.org http://propelorm.org
    Docker https://leanpub.com/dockerfordevs, Vagrant https://puphpet.com
    

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80. Joe Ferguson
    Twitter: @JoePFerguson
    Email: joe@joeferguson.me
    Freenode: joepferguson
    Contact Info:
    https://joind.in/talk/4e1b4
    

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