Writing a Django e-commerce framework

Transcript

1. Writing a Django e-commerce framework David Winterbottom @codeinthehole

2. Synopsis • Background / challenges • Why django / python

   • Customising django apps • E-commerce tips
3. None
4. None
5. None

6. Background

7. • 5 years of e-commerce projects • PHP / Python

   / Django • Lots of war stories

8. Books

9. Bookshop domain • Millions of products • ISBNs, BIC categories,

   authors, publishers • Automated feed-driven processing • Catalogue • Stock • Rich data

10. Two tier structure • Application tier - serves HTTP requests

    • Processing tier • Download and import feeds • Data cleaning and processing

11. More books

12. Different... • Fulfilment partners • Stock logic • Payment partners

    • Multiple payment sources • Complicated offers • eBooks!

13. PHP framework • Customisation via include path overrides • Lots

    of duplication • Hard to upgrade • Not-invented-here syndrome

14. Nailvarnish

15. T-shirts

16. Digital music

17. Bar equipment

18. New requirements • Product variations - colours, sizes etc •

    New fulfilment processes • Pricing models

19. B2B • Sales reps • Tax rules • Managed budgets

    • Integration with “enterprise” software

20. • Original assumptions all broken • Domains vary wildly •

    Lots of work-arounds
21. None

22. Requirements • Agnostic - few assumptions as possible • Models

    domain • without duplication • without too much meta-data

23. EAV ENTITY ATTRIBUTE VALUE Product Weight 150 Order Cost centre

    ZPAN
24. None
25. None

26. • Leather gloves

27. Bendy bits

28. Taxonomy

29. Stock

30. Shipping

31. Payment

32. and also...

33. None

34. Nothing is sacred

35. None
36. None

37. django-oscar • Django 1.3 • Experience of last 5 years

    baked into models • Lean core • Different customisation path
38. None

39. Lots of others • Satchmo • Lightning-Fast-Shop • Satchless •

    Django-shop • Plata, Mamona, Cartridge, ... • http://djangopackages.com/grids/g/ecommerce/
40. None

41. Decimals

42. None
43. None
44. None

45. kwargs

46. Shipping calculator

47. PHP

48. None
49. None
50. None
51. None
52. None
53. None
54. None

55. Python

56. None
57. None

58. Web framework • Well-thought out structure • Templating, HTTP, caching,

    ... • Good test support • Security • Class-based views

59. Models • Models drive the design • Capture domain logic

    • Foundation for rest of application

60. Eco-system • Haystack (search) • South (database migrations) • Celery

    (job queue) • Internal libraries
61. None

62. Customisation

63. Techniques

64. DEBUG = True settings.py

65. AUTH_PROFILE_MODULE = ‘customer.Profile’ settings.py

66. Key idea • Having the same name/identifier as your parent

    • Subclass and override

67. Templates

68. None
69. None
70. None
71. None

72. Django looks here first

73. Views

74. Oscar default

75. urls.py

76. oscar/app.py

77. oscar/core/app.py

78. oscar/apps/checkout/app.py

79. Oscar project

80. Replace application urls.py

81. myproject/app.py Use different app instance

82. myproject/checkout/app.py Use different view classes

83. myproject/checkout/views.py Override and extend method

84. Models

85. Oscar default

86. settings.py

87. abstract_models.py

88. models.py

89. Oscar project

90. replaces oscar app settings.py same ‘app label’

91. add custom fields myproject/voucher/models.py import remaining models

92. templatetags management commands fixtures settings.py

93. Classes

94. model name ‘app label’

95. module path class name

96. use same class name as in core

97. Recap • Bit of a work-around... • ...but works well

    • Applicable to other django libraries

98. Best practices

99. Log everything ...except bankcard details.

100. Audit models

101. None

102. Monitor everything watch high and low thresholds

103. SOA • Services make your life easier • Keep a

     layer in front of your models • Facade design pattern

104. View

105. View Models Database Load business objects

106. View Service Models Database Load business objects Business logic here

107. View Service Models Database Load business objects Business logic here

108. View Service Models Database Load business objects Business logic here

109. Rules of thumb • Keep views lean • Business logic

     in: • Models • Services • Validation logic in forms
110. None

111. Danger

112. Domain pollution • When integrating with a 3rd party... •

     they will try and push their shortcomings into your platform
113. None

114. Anti-corruption layer Your platform Their platform Anti-corruption layer

115. Summary • Django e-commerce is an emerging force • Customising

     django apps isn’t easy • Oscar’s future: • NoSQL • Table inheritance

116. Image credits Books: http://www.flickr.com/photos/th3ph17/3091294342/ More books: http://www.flickr.com/photos/cheryl-j/3965942320/ Nail varnish: http://www.flickr.com/photos/greenzowie/5451402463/

     Leather gloves: http://www.flickr.com/photos/theopenseas/175598276/ Lego shipping: http://www.flickr.com/photos/lydiashiningbrightly/5356210011/ Rubber gloves: http://www.flickr.com/photos/recyclethis/139373445/ Warehouse: http://www.flickr.com/photos/23748404@N00/15648677/ Taxonomy: http://www.flickr.com/photos/kqedquest/831547339/ T-shirts: http://www.flickr.com/photos/blazerman/177165473/