1. EE Squashed
Debugging in ExpressionEngine

2. Why?

3. The Request
GET /index.php

4. What’s Happening?
Request
index.php
core/CodeIgniter
controllers/EE
libraries/Core
libraries/Template
Output!

5. CodeIgniter
Request
index.php
core/CodeIgniter
controllers/EE
libraries/Core
libraries/Template
Output!

6. ExpressionEngine
Request
index.php
core/CodeIgniter
controllers/EE
libraries/Core
libraries/Template
Output!

7. Request
index.php
core/CodeIgniter
controllers/EE
libraries/Core
libraries/Template
Output!

8. Request
index.php Set non-standard
system path
core/CodeIgniter
$system_path = '../sys';
controllers/EE
libraries/Core Kick off CodeIgniter
require_once BASEPATH.'core/
libraries/Template CodeIgniter'.EXT;
Output!

9. Run CodeIgniter
Request LOAD: core/Common
LOAD: core/Compat
LOAD: config/constants
index.php LOAD: core/Benchmark
LOAD: core/Hooks
RUN: pre-system HOOK
LOAD: core/Config
core/CodeIgniter LOAD: core/Unicode
LOAD: core/URI
LOAD: core/Router
controllers/EE LOAD: core/Output
RUN: cache_override HOOK
LOAD: core/Input
libraries/Core LOAD: core/Lang
LOAD: core/Base[4,5]
LOAD: core/Controller
LOAD: EE
libraries/Template RUN: pre_controller HOOK
INSTANTIATE: EE
RUN: post_controller_constructor HOOK
Output! RUN: EE/index
RUN: post_controller HOOK
RENDER: output
RUN: post_system HOOK

10. Run CodeIgniter
Request LOAD: core/Common
LOAD: core/Compat
LOAD: config/constants
index.php LOAD: core/Benchmark
LOAD: core/Hooks
RUN: pre-system HOOK
LOAD: core/Config
core/CodeIgniter LOAD: core/Unicode
LOAD: core/URI
LOAD: core/Router
controllers/EE LOAD: core/Output
RUN: cache_override HOOK
LOAD: core/Input
libraries/Core LOAD: core/Lang
LOAD: core/Base[4,5]
LOAD: core/Controller
LOAD: EE
libraries/Template RUN: pre_controller HOOK
INSTANTIATE: EE
RUN: post_controller_constructor HOOK
Output! RUN: EE/index
RUN: post_controller HOOK
RENDER: output
RUN: post_system HOOK

11. Run CodeIgniter
Request LOAD: core/Common
LOAD: core/Compat
LOAD: config/constants
index.php LOAD: core/Benchmark
LOAD: core/Hooks
RUN: pre-system HOOK
LOAD: core/Config
core/CodeIgniter LOAD: core/Unicode
LOAD: core/URI
LOAD: core/Router
controllers/EE LOAD: core/Output
RUN: cache_override HOOK
LOAD: core/Input
libraries/Core LOAD: core/Lang
LOAD: core/Base[4,5]
LOAD: core/Controller
LOAD: EE
libraries/Template RUN: pre_controller HOOK
INSTANTIATE: EE
RUN: post_controller_constructor HOOK
Output! RUN: EE/index
RUN: post_controller HOOK
RENDER: output
RUN: post_system HOOK

12. Request
index.php
core/CodeIgniter
Kick off
controllers/EE ExpressionEngine
$this->core->_initialize_core();
libraries/Core
libraries/Template
Output!

13. Request
index.php
Run ExpressionEngine
core/CodeIgniter LOAD: Database
LOAD: Site Preferences
LOAD: libraries/Functions
controllers/EE LOAD: libraries/Extensions
LOAD: libraries/Localize
LOAD: libraries/Session
libraries/Core LOAD: languages/english/core
LOAD: libraries/Template
RUN: template/run_template_engine
libraries/Template
Output!

14. Request
index.php
Run ExpressionEngine
core/CodeIgniter LOAD: Database
LOAD: Site Preferences
LOAD: libraries/Functions
controllers/EE LOAD: libraries/Extensions
LOAD: libraries/Localize
LOAD: libraries/Session
libraries/Core LOAD: languages/english/core
LOAD: libraries/Template
RUN: template/run_template_engine
libraries/Template
Output!

15. Request
index.php Parse the Template
Parses URI
core/CodeIgniter Fetch template from DB
Fetch template from disk
Static check
Parse snippets, segments, embed:vars
controllers/EE Check cache
Parse input PHP
Parse simple conditionals
libraries/Core Parse tags
Parse output PHP
Write cache
libraries/Template Parse advanced conditionals
Loop through sub-templates
Output!

16. Request
index.php Parse the Template
Parses URI
core/CodeIgniter Fetch template from DB
Fetch template from disk
Static check
Parse snippets, segments, embed:vars
controllers/EE Check cache
Parse input PHP
Parse simple conditionals
libraries/Core Parse tags
Parse output PHP
Write cache
libraries/Template Parse advanced conditionals
Loop through sub-templates
Output!

17. Request
index.php
core/CodeIgniter
controllers/EE
libraries/Core
libraries/Template
Output!

18. What’s Happening?
Request
index.php
core/CodeIgniter
controllers/EE
libraries/Core
libraries/Template
Output!

19. Debugging
Debugging is a methodical process of finding and
reducing the number of bugs, or defects, in a computer program or a
piece of electronic hardware, thus making it behave as expected.
–wikipedia

20. Debugging
Debugging is a methodical process!

21. KISS
Don’t assume anything
Attack the obvious
Ask for help
Start broad

22. When you assume…
Don’t assume it’s an extension
Don’t assume it’s the database
Don’t assume it’s your host
Don’t assume…
It’s much faster to determine what the problem is
than what the problem isn’t.

23. Is it plugged in?
Can you SSH/FTP?
Can you access a static HTML file?
Can you access your database?
Can you access PHP info?

24. Help!
Xdebug Extension for PHP
http://xdebug.org/
Display Output Profiler
$config[‘show_profiler’] = TRUE;

25. Broad strokes
Check the application, can you log into the CP?
Check the templates, can you access other
pages?
Remove half the template, does it show up?
Remove a fourth the template, does it show up?
Rinse, repeat…

26. KISS Huot Style
1. Test a static file
2. Test the control panel
3. Test other templates
4. Remove the entire trouble template, replace it
with “test”
5. Fill back in the template until it breaks

27. KISS Huot Style
6. Is the trouble spot fixable in the template?
7. If not open the add-on and place debugging
lines throughout
8. Is the trouble spot in the add-on?
9. If not open the core EE files and place
debugging lines throughout

28. Three Examples

29. 1.
Data’s Gone Missing

30. The Problem
4:30 pm
on a Friday

31. Assumptions…
Let’s do it all wrong.

32. It’s EE’s Fault
An entry was overwritten?
An entry was accidentally deleted?
An entry was set to closed?

33. It’s MySQL’s Fault
The database is corrupt?
Primary keys are out of order because of a
backup or import?

34. Now, I feel like an ass.

35. KISS
Don’t assume anything
Attack the obvious
Start broad
Ask for help

36. Is it plugged in?
Check with the client, what is really missing?
Can they tell you anything about the data?
What channel it was in?
What status they set it to?
5:58 pm
on a Friday

37. The Solution
“Don't worry Mark, they never existed in the DB. We got to
the bottom of it. I'm adding them by hand tomorrow. Sorry for
all the confusion.”
6:23 pm
on a Friday

38. 2.
Finicky URLs

39. The Problem
Every listing page just stopped working.

40. Yesterday

41. Today

42. Background
Project rolled seven sites into one.
Each sub-site was different and contained
separate IA (navigation).

43. Under the Hood
Standard EE 1.x install
No custom add-ons
Not using Pages module
“Templates as controllers”

44. Yesterday

48. Assumptions…
Let’s do it all wrong.

49. It’s EE’s Fault
Have the templates changed?
Was something new installed/enabled?
Is it daylight savings time?

50. Now, I feel like an ass.

51. KISS
Don’t assume anything
Attack the obvious
Start broad
Ask for help

52. Ask For Help

53. Ask For Help

54. Ask For Help

55. The Solution
For now, I’ve renamed entry.
I’m open to suggestions, please feel free to
educate me after this session with your ideas.

56. 3.
EE Can’t Count

57. The Problem
Contestants aren’t sorting properly.

60. Under the Hood
Standard EE 2.x install
EE Members
EE Member Custom Profile Fields
Mark Huot Vote Module
Solspace User Module

61. All together now…
The Vote module records votes in a separate
database table.
The Vote module summarizes total votes into a
standard EE member profile field.
The User module displays users ordered by the
EE member profile field.

62. Assumptions…
Let’s do it all wrong.

63. It’s EE’s Fault
Values are correct in
control panel.

64. It’s Vote’s Fault
Module code looks correct.
Correctly using
exp_member_data table.
Pulling correct custom
field, I think…

65. It’s User’s Fault
Nope, template appears
correct.
Sorting by other fields
works as expected
(username, other custom
fields).
Sort attribute correctly flips
the results, but keeps them
out of order.

66. It’s My Fault
Template looks right.
Not a CSS issue,
underlying XHTML is
wrong too.

67. Now, I feel like an ass.

68. KISS
Don’t assume anything
Attack the obvious
Start broad
Ask for help

69. Help!

75. What’d we Learn?

76. Don’t guess.