Drupal 7 introduced many new APIs, most notably the Field API. The Field API is a powerful but complex system that defines the structure and behavior of fields. It introduces several new concepts including bundles, field storage, field types, widgets, and formatters. Fields describe the data structure and behavior, while instances store widget and formatter settings and are easier to update. The Field API provides functions to attach, load, and update fields on entities. It handles fields already attached rather than the attachment process itself. Taxonomy terms are also now full entities with their own API.

1. Drupal 7: What's new Karoly Negyesi Clarity Digital (examiner.com)

3. Tons of new APIs

4. Most of them are well documented and easy

5. Field API: many new concepts and gotchas

7. API and not browser driven

8. Our work now is “precision surgery”

10. Field storage

11. Field types

12. Widgets

13. Formatters

14. Fields

15. Attach

16. Instances

18. Primary identifier: nid

19. Version identifier: vid

21. Primary identifier: tid

22. Version identifier: tid (same)

24. Bundle: node type

25. Primary id: nid

27. Bundle: vocabulary

28. Primary id: tid

31. Cornerstone of scalability

32. MongoDB

34. Text, file, image...

35. Gotcha: extremely badly named hooks. for eg. hook_field_load node-like “one only” hook should be field_type not field .

37. Field type

38. Cardinality

39. Storage engine

40. All the things that are hard to upgrade

41. Core does not upgrade

43. (a) Field

44. (to a) Bundle

45. (is an) Instance

47. Widget settings

48. Formatter settings

49. Trivial to update

50. Gotcha: formatter settings are stored in 'display'

52. Hard to update

53. Instances are trivial to update

54. Instances are mostly just widget / formatter

56. Generic: textfield, textarea, options_select...

57. Specific: Image (but there is always an alter)

59. Generic

60. Specific (yes, we have an alter here too)

62. field_attach_presave('node', $node);

63. These call same named hooks

64. module_invoke_all('field_attach_presave', $obj_type, $object);

65. hook arguments are entity type and the entity

66. Gotcha: does not deal with attaching a field

67. But at least it's a real hook.

69. Instances can be found: field_info_instances($obj_type, $bundle)

71. Entity type variables are typically $obj_type

72. Similarly, entities are $object

73. Formatter settings are in $instance['display']

74. The field attach API deals with fields already attached aka. Instances and not the attach itself

76. Taxonomy_term_reference

77. Hiearchy is not a field

79. user_module_invoke('update', $edit, $user, $category);

80. entity_invoke('update', 'user', $user);